mod 7 maint pract

7/23/2019 Mod 7 Maint Pract

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Contents

1. SAFETY PRECAUTIONS..........................................................................1

1.1 compressed gas................................................................................11.1.1 Purpose of The Gases........................................................11.1.2 Gas Cylinder Identification..................................................11.1.3 Safety Precautions.............................................................3

1.1.4 Charging Rigs ...................................................................31.1. Cascade Charging..............................................................31.1.! "efore #se Chec$s.............................................................31.1.% &ircraft Compressed Gas Charging ...................................41.1.' &ircraft Gas Charging (al)es.............................................41.1.* Typical Gas Charging Precautions.....................................

1.2 electric shoc$....................................................................................

1.3 fire precautions.................................................................................!1.3.1 Classification of +ires..........................................................!1.3.2 +ire ,-tinguishing &gents...................................................!1.3.3 +ire ,-tinguisher Identification............................................%

1.3.4 General Precautions...........................................................'1.3. Procedure n disco)ering a fire in the /or$0Place............*1.3.! &ction to e Ta$en in the ,)ent of ,ngine +ires.................*1.3.% &ction to e Ta$en in the ,)ent of "ra$e +ires...................*

1.4 the need for safety............................................................................*

1. or$ing around aircraft......................................................................1

2. WORKSHOP PRACTICES........................................................................1

2.1 care use of tools............................................................................1

2.2 use of materials.................................................................................1

2.3 dimensions........................................................................................2

2.4 &55/&6C,S Tolerance.............................................................32. caliration of tools e7uipment........................................................3

3. TOOLS......................................................................................................1

3.1 common hand tools...........................................................................13.1.1 8ar$ing ut Tools..............................................................13

3.2 common poer tools.........................................................................1*3.2.1 ,lectric 9and :rills.............................................................1*3.2.2 Pneumatic Tools.................................................................1*3.2.3 Care of &ir perated Tools Safety Precautions...............23

3.3 precision measuring tools.................................................................243.3.1 8icrometers........................................................................243.3.2 #sing 8icrometers..............................................................2!3.3.3 (ernier 8easuring Instruments...........................................2%

5#"RIC&TI6.......................................................................................313.3.4 Purpose..............................................................................313.3. il313.3.! Greases..............................................................................313.3.% 5imitation of ils and Greases............................................313.3.' 5urication Charts..............................................................32

4. ENGINEERING DRAWING.......................................................................1

4.1 draing types....................................................................................1

4.1.1 6T,S 6 :R&/I6G.......................................................44.2 symols.............................................................................................4

8aintenance Practices "1 y C"C



4.2.1 /elding Symols................................................................4.2.2 Surface +inish.....................................................................!4.2.3 Standard Con)entions........................................................% &re)iations..............................................................................*

4.3 dimensions........................................................................................*4.3.1 5eader; Pro<ection :imensioning 5ines...........................114.3.2 Redundant :imensions......................................................114.3.3 9oles Radii......................................................................124.3.4 &ngles Chamfers.............................................................12

4.4 tolerance.........................................................................................134.4.1 5imits and Tolerances.........................................................134.4.2 Geometric Tolerance..........................................................134.4.3 Indicators of Geometric Tolerance......................................14

4. pro<ections........................................................................................144..1 rthographic Pro<ection......................................................144..2 Pictorial Pro<ections............................................................1!

4.! title loc$ information........................................................................1%4.!.1 "orders +rames..............................................................1%4.!.2 &mendment to :raings....................................................1%

4.% micro0film micr0fiche....................................................................1'

4.' computerised presentations..............................................................1'

4.* ata 1 specification.........................................................................1*

4.1 aeronautical standards....................................................................2

4.11 iring diagrams...............................................................................2

4.12 schematic diagrams........................................................................2

5. FITS CLEARANCES..............................................................................2!

.1 Si=es of 9oles...................................................................................2%

.2 Classes of +it....................................................................................2%.2.1 Clearance +it......................................................................2%

.2.2 Interference +it...................................................................2%.2.3 Transition +it.......................................................................2'

.3 common systems of fits clearances...............................................2'.3.1 Shaft and 9ole "asis..........................................................2'.3.2 #nilateral and "i0lateral......................................................2*.3.3 5imit System.......................................................................2*

". AIRCRAFT WEIGHT #ALANCE...........................................................1

!.1 purpose.............................................................................................1

!.2 <ar ops re7uirements.........................................................................1

!.3 principles of eight and alance.......................................................1

!.4 definitions..........................................................................................2!. eight and centre of gra)ity schedule...............................................3

!.! principles of aircraft eight and alance...........................................4

!.% preparation for eighing....................................................................!

!.' eighing on aircraft <ac$s..................................................................!

!.* standard mean chord >s.m.c.?...........................................................'

!.1 changes in asic eight..................................................................'

!.11 e-amples of alterations to asic eight...........................................*

!.12 loading of aircraft............................................................................1

!.13 documentation................................................................................12

!. AIRCRAFT HANDLING STORAGE.......................................................1




%.1 ta-iing @ toing associated Safety Precautions..............................1%.1.1 8o)ing 8ethods ..............................................................1

%.2 <ac$ing @ choc$ing securing associated safety precautions............11%.2.1 Special Considerations.......................................................11%.2.2 &ircraft Aac$s......................................................................11%.2.3 Aac$ 8aintenance General 6otes...................................14%.2.4 &IRCR&+T Aac$ing Precautions.........................................14%.2. Aac$ing Procedure..............................................................1%.2.! 5oering &ircraft.................................................................1

%.2.% Trestles...............................................................................1!%.2.' 5ifting Tac$le......................................................................1!

%.3 par$ing securing &IRCR&+T..........................................................1%%.3.1 Securing @ Pic$eting @ 8ooring............................................1'%.3.2 Typical Small &ircraft Procedure.........................................1'

%.4 ground de0icing anti0icing...............................................................2%.4.1 Ground :e0icing of &ircraft.................................................2%.4.2 :e0Icing and &nti0Icing.......................................................2%.4.3 8ethods of :e0Icing...........................................................2%.4.4 Safety 6otes.......................................................................22%.4. &nti0icing.............................................................................22

%.4.! :e0icing Paste....................................................................2%.4.% Inspection &fter :e0icing perations .................................2

%. storage..............................................................................................2!

%.! refuelling defuelling........................................................................2*%.!.1 Refuelling &ircraft...............................................................2*%.!.2 Refuelling Safety Precautions ............................................2*%.!.3 Chec$ing +uel Contents.....................................................3%.!.4 typical aircraft +#,55I6G information >ae 14!?................3

%.% ground supplies.................................................................................4%.%.1 ,lectrical.............................................................................4%.%.2 9ydraulic............................................................................41

%.%.3 Pneumatic..........................................................................41%.%.4 ,ffects of ,n)ironmental Conditions on &ircraft 9andling peration.....................................................................................41

$. INSPECTION REPAIR TECHNI%UES...................................................1

'.1 corrosion assessment reprotection................................................1'.1.1 Pre)entati)e 8aintenance..................................................1'.1.2 Corrosion Remo)al.............................................................1'.1.3 Corrosion f +errous 8etals..............................................2'.1.4 9ighly Stressed Steel Components....................................2'.1. Pre)ention f Corrosion ....................................................2'.1.! &luminium and &luminium &lloys........................................3

'.1.% &lclad..................................................................................3'.1.' Typical Painted Corrosion Treatment Se7uence................3'.1.* Permanent &nti0Corrosion Treatments...............................4'.1.1 acid spillage......................................................................'.1.11 &l$ali Spillage...................................................................'.1.12 8ercury Spillage...............................................................'.1.13 Identification of 8etals......................................................!

'.2 non destructi)e testing......................................................................%'.2.1 introduction.........................................................................%'.2.2 "asic 8ethods....................................................................%'.2.3 optical 6:T methods..........................................................%'.2.4 dye penetrant testing..........................................................''.2. Penetrant Testing...............................................................*




'.2.! ultra sound testing..............................................................1'.2.% eddy current testing............................................................12'.2.' magnetic particle testing.....................................................13'.2.* radiographic 8isc. testing................................................14'.2.1 8isc. Techni7ues..............................................................1!

'.3 TBP,S + :,+,CT &6: )isual inspection techni7ues...................1%'.3.1 Inspection...........................................................................1%'.3.2 /hat Type of defects..........................................................1%

'.4 troule shooting techni7ues..............................................................1*'.4.1 Confirmation@identification of the fault.................................1*'.4.2 +ault +inding Techni7ues...................................................1*'.4.3 n "oar: 8aintenance Systems........................................1*'.4.4 +ault Isolation 8anual@Troule Shooting 8anual................2

&. A#NOR'AL E(ENTS...............................................................................1

*.1 Introduction.......................................................................................1

*.2 Types of anormal occurrence..........................................................1

*.3 Type of damage................................................................................1

*.4 lighting stri$es hirf penetration.......................................................1*.4.1 ,ffect of a 5ightning stri$e..................................................2

*.4.2 Inspection...........................................................................2*.4.3 9igh Intensity Radiated +ields >9IR+?................................2*.4.4 Protection &gainst 9IR+.....................................................2

*. Typical 8anufacturers Information >"oeing %%?...............................3*..1 General Information............................................................3*..2 "asic Protection..................................................................3*..3 Stri$e &reas........................................................................3*..4 Signs of :amage................................................................3*.. ,-ternalComponents..........................................................4*..! ,lectrical Components........................................................*..% ,-amination of ,-ternal Surface.........................................

*..' +unctional Tests.................................................................!*..* ,-amination of Internal Components..................................!*..1 Return The &ircraft to Ser)ice...........................................%

1). 'AINTENANCE PROCEDURES............................................................1

1.1 modification procedures..................................................................11.1.1 design modifications.........................................................1

1.2 stores procedures...........................................................................1.2.1 &ppro)ed Parts.................................................................1.2.2 Goods Inard procedure..................................................1.2.3 storage conditions............................................................11.2.4 atch numer....................................................................11

1.2. authorised release documents .........................................111.2.! ogus parts.......................................................................12

1.3 Certification@Release Procedures....................................................11.3.1 Introduction.......................................................................11.3.2 Certificate of Release to Ser)ice.......................................11.3.3 CRS Statement >/hat does a signature signify?.............11.3.4 /hat if you are Certifying another personDs or$............1!

1.4 maintenance planning.....................................................................1%1.4.1 Technical Records............................................................1%1.4.2 Ao 6umer......................................................................1%1.4.3 /RES9,,TS................................................................1'

1.4.4 /REP&CES..................................................................1'1.4. Planning...........................................................................1'




1. 8aintenance Inspection..................................................................211..1 Introduction.......................................................................211..2 planning the maintenance schedule.................................211..3 &8,6:8,6TS T &PPR(,: 8&I6T,6&6C,SC9,:#5,S..............................................................................221..4 Condition 8onitoring 8aintenance...................................2%1.. The 8aintenance Steering Group >8SG? &pproach ........2*1..! The 8aintenance Schedule..............................................11..% Information in a typical Schedule......................................2

1.! interface ith aircraft operation ......................................................1.!.1 &IR5I6, SC9,:#5I6G...................................................1.!.2 8aintenance pportunities ..............................................!1.!.3 8aintenance 0 Ideal production re7uirements...................!

1.% 7uality control @ 7uality assurance...................................................'1.%.1 9o is 7uality chec$ed.....................................................'1.%.2 ,-ternal (erification..........................................................'

11. AIRCRAFT CA#LES...............................................................................&

11.1 applicale re7uirements..................................................................*11.1.1 &irorthiness codes..........................................................*11.1.2 :esign responsiility.........................................................*11.1.3 &ppro)al of cales............................................................111.1.4 8odification repair.........................................................1

11.2 cale classification..........................................................................1111.2.1 &irframe cales.................................................................1111.2.2 Interconnect cales..........................................................1111.2.3 ,7uipment ire.................................................................1211.2.4 +ire resistant cales..........................................................1211.2. +ireproof cales................................................................1211.2.! 8ulti0core; Screened and Aac$eted cales.......................1211.2.% :ata "us...........................................................................1211.2.' Ignition cales...................................................................13

11.2.* Thermocouple cales.......................................................1311.2.1 Co0a-ial cales...............................................................13

11.3 specification cale type identification...........................................1311.3.1 "ritish Standards Specifications.......................................1311.3.2 #E 8ilitary Specifications.................................................1411.3.3 #S 8ilitary Specifications.................................................1411.3.4 ConstructorDs Specification...............................................1411.3. International >including ,uropean? Standards...................1411.3.! Cale 8anufacturerDs Specifications.................................1

11.4 cale performance..........................................................................111.4.1 &pplication........................................................................1

11.4.2 Temperature.....................................................................111.4.3 Cale si=e.........................................................................1!11.4.4 (oltage rating...................................................................1!11.4. Current rating....................................................................1!11.4.! +lammaility to-icity......................................................1%11.4.% /et &rc Trac$ing..............................................................1%11.4.' 8echanical properties.......................................................1%11.4.* +luid contamination..........................................................1%

11. cale construction...........................................................................1'11..1 Conductors.......................................................................1'11..2 Conductor Plating.............................................................1'11..3 :ielectric materials @ cale types......................................1'

11.! cale failure.....................................................................................2

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11.!.1 /et &rc Trac$ing..............................................................211.!.2 8iny)in.............................................................................211.!.3 "8S 1302'........................................................................211.!.4 &rasion...........................................................................211.!. Conductor FEnuc$ling throughF..........................................211.!.! Red Plague.......................................................................2111.!.% Glycol +ires.......................................................................2111.!.' Poor Solderaility.............................................................21

11.% caa appro)ed cales.......................................................................21

11.%.1 ".I.C.C..............................................................................2211.%.2 Rists /ire and Cale 5td..................................................2411.%.3 Raychem 5imited..............................................................211.%.4 Societe +ilote-..................................................................2%11.%. Eaeler$e Reinshagen Gmh........................................2'11.%.! 9uer and Suhner &G......................................................2'

11.' caa osolescent cales...................................................................2*11.'.1 ".I.C.C..............................................................................2*11.'.2 +othergill and 9ar)ey 5imited...........................................2*11.'.3 Rists /ire and Cales 5td................................................2*11.'.4 Societe +ilote-..................................................................2*

11.'. +ileca................................................................................2*11.* cale identification..........................................................................3

11.*.1 8anufacturersD identification mar$s..................................311.*.2 Country of origin identification mar$s................................3

11.1 identification of installed cales.....................................................3111.1.1 "asic cale coding system.............................................3111.1.2 8anufacturers coding.....................................................34

12. CA#LE INSTALLATIONS.......................................................................1

12.1 support of caling............................................................................1

12.2 lacing..............................................................................................1

12.3 protecting cales.............................................................................212.3.1 Synthetic ruer slee)es..................................................212.3.2 9eat Shrin$ Slee)ing........................................................212.3.3 /rapping..........................................................................312.3.4 Ruer eading grommets............................................312.3. Conduits...........................................................................312.3.! Cale seals.......................................................................3

13. TER'INATING CA#LES........................................................................1

13.1 crimped terminations.......................................................................113.1.1 Crimping ring; tag and spade type terminations................113.1.2 ,rma crimping machine....................................................'

13.1.3 Crimping of connector pins soc$ets...............................*13.1.4 Terminating screened cales............................................1

13.2 soldering.........................................................................................1413.2.1 Soldering Irons.................................................................1413.2.2 Solder...............................................................................113.2.3 +lu-...................................................................................113.2.4 9eat Sin$s........................................................................1!13.2. &nti0/ic$ing tool...............................................................1!13.2.! Soldering procedure.........................................................1%13.2.% Inspection of soldered <oints.............................................1%13.2.' Common soldering faults..................................................1'13.2.* :esoldering methods........................................................1*

13.3 ire0rapping of electrical connections...........................................21

8aintenance Practices "1 y C"C Page !



13.3.1 Types of /ire0/rap..........................................................2113.3.2 Tools.................................................................................2113.3.3 /ire0/rapping procedure.................................................2213.3.4 Incorrect /ire0/rapping...................................................2313.3. 8odification and Repairs..................................................2313.3.! 8ethods of inspection.......................................................24

14. INTERCONNECTING CA#LES..............................................................25

14.1 terminal strips..................................................................................2

14.1.1 S"&C terminal loc$s.......................................................214.1.2 Plessey terminal loc$s....................................................2!14.1.3 /ard "roo$ terminal loc$s..............................................2!14.1.4 Terminal Aunction 8odule.................................................2%

14.2 connectors......................................................................................2'

15. 'EASURING INSTRU'ENTS................................................................1

1.1 asic mo)ing coil type.....................................................................11.1.1 Construction.....................................................................11.1.2 Principle of operation........................................................21.1.3 :amping...........................................................................31.1.4 Paralla- error....................................................................3

1.1. 8eter position...................................................................41.1.! ,-tending the meter range...............................................41.1.% 8eter loading....................................................................1.1.' hmDs per )olt..................................................................1.1.* 8easuring resistance........................................................!

1.2 ratiometer type instruments.............................................................%1.2.1 The "onding tester...........................................................%1.2.2 The Insulation Resistance tester.......................................*1.2.3 Carrying out an insulation resistance test.........................1

1". AIRCRAFT 'ANUALS............................................................................1

1!.1 large commercial aircraft.................................................................1

1!.1.1 &T& 1...........................................................................11!.2 light aircraft manuals.......................................................................%

1!. CIRCUIT SY'#OLS................................................................................$

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Intent*on+,,- #,+n

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1. SAFETY PRECAUTIONS

&)iation engineers fre7uently or$ in potentially dangerous en)ironments.(irtually e)ery aspect of aircraft maintenance can e potentially ha=ardous. It iso)ious that engineers must e trained to e aare of these potential dangers sothat precautions can e ta$en to minimise them. ,ach part of your training illemphasise particular ha=ards associated ith the su<ect. In this section e illloo$ at the particular care that should e ta$en hen or$ing ith compressed

gasses; electricity oils and chemicals. /e shall also consider the safetyprecautions and procedures rele)ant to fire in the or$place.

1.1 CO'PRESSED GAS

Compressed gases are in common use in a)iation. They are re7uired duringnormal day to day aircraft maintenance. 6itrogen; Caron :io-ide and -ygenare all usually present on the flight line.

1.1.1PURPOSE OF THE GASES

N*t/o0en is used for aircraft tyre inflation; aircraft hydraulic system accumulators;fuel tan$ inhiiting and shoc$ strut inflation.

C+/on D*o*e is used in fire e-tinguishers and for life <ac$et and other safetye7uipment inflation ottles.

O-0en is used for aircraft emergency reathing for aircre and passengers.

Aet-,ene is used in gas elding e7uipment.

1.1.2GAS CYLINDER IDENTIFICATION

It is )ital that a gas cylinder must e positi)ely identified to pre)ent possiledisastrous results of charging a system or component ith the rong gas. In thepast; the accepted practice as to paint the cylinder in a distincti)e colour andalso to paint the name of the gas on the cylinder in letters of a contrasting colour.In the #E; gas cylinders are normally supplied y The "ritish -ygen Company

>"..C.?. The cylinders are colour coded in accordance ith "ritish Standard3'1 C; ut it is no longer compulsory for the suppliers or users of compressedgases to follo itFs re7uirements. The only positi)e method of identifying thecontents of a gas cylinder is to read a lael on the nec$ of the cylinder; shoingthe cylinder contents; the gas pressure and any special safety re7uirements. It iscompulsory for this lael to e attached to the cylinder during transportation ofthe cylinder. If colour coding is used; the normal con)ention in the #E is asfollos.

N*t/o0enCo,o/ 5ight Grey ith "lac$ nec$

Lette/*n0 0 6itrogen in "lacEUse Charging aircraft accumulators; tyres; shoc$ asorers;

O-0enCo,o/ 0 "lac$ ith /hite nec$

Lette/*n0 0 -ygen in /hiteUse 0 &ircre Passenger reathing

C+/on D*o*eCo,o/ "lac$

Lette/*n0 0 Caron :io-ide in /hiteUse 0 +ire ,-tinguishers and Safety ,7uipment

Aet-,ene

Co,o/ 0 8aroonLette/*n0 0 &cetylene in /hite

8aintenance Practices "1 y C"C Page 1



Use 0 Gas /elding




1.1.3SAFETY PRECAUTIONS

The storage or Htransport cylinders supplied y "C are large >appro-imately !ftlong? and contain gas at a pressure of 4; 0 !; pounds per s7uare inch>p.s.i.?. ,-treme care must e ta$en hen or$ing ith gas at this pressure. Ifthe ottles are dropped or damaged they could e-plode or propel the cylinder athigh )elocity li$e a roc$et pro<ectile. Gas at pressure as lo as 1 p.s.i. canin<ect into the s$in and cause serious; e)en fatal in<uries. Some gasses support

comustion and ill ma$e fires urn much more fiercely. -ygen is particularlydangerous as it is also capale of causing e-plosions hen in contact ith oils orgreases. -ygen safety precautions ill e dealt ith in more detail in module

11.

1.1.4CHARGING RIGS

&ircraft gas cylinders contain gas at a much loer pressure and so the gas isdecanted from the larger Htransport cylinders. & charging trolley is often used;this eing generally a toed trolley ith one; to or e)en four high0pressure gascylinders; a fle-ile supply hose; a supply shut0off )al)e; and pressure gaugesshoing supply pressure and storage cylinder pressure. Some rigs are alsofitted ith a pressure regulator; y means of hich the supply pressure can e

limited to the ma-imum re7uired y the component or system. &lternati)ely afi-ed charging rig may e used.

1.1.5CASCADE CHARGING

This is a procedure that should e adopted hen gas charging to a)oid astageof gas. If not used; the result could e a set of four gas ottles; each ith asustantial amount of gas at slightly loer pressure than the ma-imum systempressure. In this process fully charged cylinders in a set; are not used for theinitial part of a charge. Partially e-hausted cylinders are used initially and higherpressure cylinders to complete the process. E+67,e8 & large capacity systemneeds to e charged to 2; p.s.i. The current pressure is p.s.i. There are

four gas ottles on the charging trolley ha)e pressures of 3;; 1;'; 1; and1; p.s.i.. Bou might e tempted to connect the ottle ith 3; p.s.i. to thesystem and charge it ith that one only. Cascade charging sa)es gas; firstcharging from the 1; p.s.i. gas ottle; then the 1; p.s.i. gas ottle and soon until the aircraft system is at 2; p.s.i. conser)ing gas for more charges.

1.1."#EFORE USE CHECKS

"efore charging ith gas; ensure the folloingJ

• Is the gas the correct type 0 Refer to identification mar$ings and@or the laelon the nec$.

• 8a$e sure the transport cylinders are correctly fitted and secure on the trolleyor rig.




• ,nsure the cylinders contain enough pressure for the charge.

• 8a$e sure the deli)ery hose is in good condition and clean.

• If -ygen gas is eing charged; there should e no o*, or 0/e+se around thecharging connections or the charging rig.

1.1.!AIRCRAFT CO'PRESSED GAS CHARGING

&ny system or component containing compressed gas must e handled and

ser)iced carefully; ecause the sudden release of gas under pressure could ha)edisastrous conse7uences. -ygen systems are an additional ha=ard in that thegas supports comustion and that oil and grease are prone to spontaneouscomustion in the presence of undiluted o-ygen. The gas pressure in somecomponents )aries according to the amient temperature; and in order to ensurethat the correct pressure is maintained; the relationship eteen temperature andpressure is generally presented in the form of a graph; oth in the 8aintenance8anual and on a placard ad<acent to the charging point. In the case of tyres orshoc$ asorers on larger aircraft; the re7uired gas pressure may )ary accordingto the aircraft eight. Since rapid compression of a gas results in an increasedtemperature; gas pressure ill also increase. n cooling don; the pressure illdrop and may result in an inaccurate reading. This effect can e minimised y

charging sloly. & sudden release of gas produces the re)erse affect i.e.loering the temperature. This is particularly important hen deflating a tyre; asice may form and loc$ the )al)e; gi)ing the impression that the tyre is fullydeflated hen it may e partially inflated. This may pro)e disastrous if the ne-tstep as to attempt to dismantle the heel. Prior to or$ on any unit from hichthe gas has een e-hausted; the charging )al)e should e completely remo)ed.

1.1.$AIRCRAFT GAS CHARGING (AL(ES

These may e of to types. ne is a needle type )al)e that opens and closesautomatically hen pressure is applied or released >Schrader )al)e?. This typeof )al)e is identical to the )al)es used in car or icycle heels. The other type of

)al)e has a nut hich must e unscreed partially efore the gas may ereleased. In oth types; a )al)e cap should alays e fitted to pre)ent entry ofdirt and moisture. The cap should e remo)ed hen the system re7uirescharging. The cap may e attached y a chain; thus pre)enting it from einglost. n no account should the )al)e ody e unscreed hile the system orcomponent is pressurised; since this could result in the )al)e loing out;causing damage or in<ury.

Charging Panel Charging (al)es

& typical aircraft gas charging panel ill comprise a charging )al)e and pressure

gauge. There is sometimes a temperature graph to sho ho the pressure )ariesith temperature.8aintenance Practices "1 y C"C Page 4



1.1.&TYPICAL GAS CHARGING PRECAUTIONS

Charging a component ith compressed gas should e carried out carefullyoser)ing the folloing precautionsJ

• The charging pressure should e chec$ed from the maintenance manual. &lso ma$e sure of the pressure units. 8ost #E engineers are familiar ithpounds per s7uare inch >p.s.i.?; ut some gauges are calirated in other unitssuch as ars >a ar is appro-imately 1 p.s.i.?. Consideration should also egi)en to the amient temperature and that the en)ironmental conditions ill

not contaminate the system conditions >rain; sno or dust?.

• The supply connection >charging hose? should e clean; dry and free from oilor greaseK any contamination should e iped off ith a lint0free cloth. Thisis )itally important hen charging o-ygen.

• The same care should e ta$en to ensure the system charging point is clean;after remo)ing the lan$ing cap.

• Generally the charging hose should e purged; y alloing gas to escape atlo pressure from the hose; prior to connection. This ensures there are noforeign odies or moisture in the hose. &gain this is )ital in the case ofo-ygen charging.

• The aircraft system should e charged sloly; so as to minimise the rise intemperature.

• /hen the re7uired pressure is reached; the shut off )al)e should e closedand the system pressure alloed to stailise after cooling don.

• The pressure should e re0chec$ed and ad<usted as necessary.

• The supply hose should not e disconnected unless the shut0off )al)e andthe charging )al)e on the charging rig are closed. n some rigs pro)ision isalso made for relie)ing pressure from the supply hose efore disconnection.

• "lan$ing caps should alays e fitted to the charging )al)e and the supply

hose after disconnection.

• /hen charging o-ygen systems; ade7uate and properly manned fire0fightinge7uipment should e positioned; and if illumination is re7uired; it should ee-plosion proof.

1.2 ELECTRIC SHOCK

This is an o)ious occupation ha=ard for oth a)ionic and mechanical aircraftengineers. 8uch of the systems and maintenance e7uipment is electricallypoered. The main dangers associated ith use of electricity areJ

• ,lectric shoc$ hich may e fatal.

• &rcing caused y inade7uate insulation. This could lead to a fire.

• )erheating hich again could lead to a fire.

8ost of the personal dangers can e pre)ented y folloing a fe simple rulesJ

• /ear the correct clothing. Personal <eellery; especially rings and metalstrapped atches should not e orn as they may get caught in machinery oract as a conductor.

• ,nsure all electrical and radio e7uipment; poer tools etc. is properlyearthed. &ll portale electrical e7uipment should e P&T >Portale &pplianceTest? tested at regular inter)als y a trained and 7ualified P&T test person.

• ,nsure all test e7uipment is properly connected.

8aintenance Practices "1 y C"C Page



• ,nsure that all interloc$s and other safety de)ices are ser)iceale and nottampered ith or o)er0ridden.

• :o not or$ on e7uipment that is sitched on. perate or remo)e theappropriate circuit protection de)ices >circuit rea$ers or fuses?.

• &lays sitch off poer efore replacing components.

• If using machines that ha)e emergency stop uttons; ensure all personnel$no their locations.

• /here possile; ensure a second person is present in case of an accident.

1.3 FIRE PRECAUTIONS

+ire is the product of a chemical reaction in hich fuel mi-es ith o-ygen andreleases heat and light. Three things are re7uired efore a fire can occurJ

• There must e a Fe,

• -ygen must e present >or air; hich contains o-ygen?

• The temperature must e raised high enough for the fuel and o-ygen tocomine.

To e-tinguish a fire; you must either cool it or e-clude the o-ygen.

+ire is proaly the most dangerous of the ha=ards associated ith aircraftmaintenance. &ircraft carry large 7uantities of fuel and other comustilematerials. There is also a large amount of electrical e7uipment on aircraft; sothere is a high ris$ of fire.

1.3.1CLASSIFICATION OF FIRES

+ires are classified into four categories. ,-tinguishers suited for eachclassification of fire are mar$ed ith the classification letter as shon in thefolloing taleJ

F*/e C,+sses Lette/ Des*0n+t*on

rdinary comustiles 0 paper; cloth; ood &

+lammale li7uids +uel; il "

,nergised electrical e7uipment C

Comustile metals "ra$e units :

1.3.2FIRE E9TINGUISHING AGENTS

+ire e-tinguishing agents should e selected appropriate to the type of fire onhich they are effecti)e.

• C,+ss A 0 fires ith such fuels as paper; ood or cloth >often called solidfuel?; can e e-tinguished ith a ater spray. This cools the fuel to atemperature elo that at hich it can urn.

• C,+ss # 0 fires are est put out ith an e-tinguisher that e-cludes the o-ygenfrom the urning fuel. :ry poder agents rea$ don in the presence of heatto produce caron dio-ide that displaces the o-ygen. Caron :io-idee-tinguishers displace the o-ygen directly. +oam is also used; hichlan$ets the fire and e-cludes the o-ygen. /ater should not e usedecause the urning fuel ill float on top of the ater.

8aintenance Practices "1 y C"C Page !



• C,+ss C 0 fires should e treated carefully ecause of the ris$ of contact ithhigh )oltages. /ater should definitely not e used as it ill conductelectricity. :ry poder ould e effecti)e; ut it is not the est choice as itlea)es a stic$y residue that ma$es cleanup difficult. Caron dio-ide is )eryeffecti)e hen sprayed )ia a non0metallic horn. The est e-tinguishers arehalogenated hydrocarons or halons.

• C,+ss D 0 fires should ne)er ha)e ater sprayed on them as it intensifies thefire and may cause an e-plosion. :ry poder is the est choice for

e-tinguishing metal fires.

1.3.3FIRE E9TINGUISHER IDENTIFICATION

The e-tinguishers should e clearly mar$ed ith the appropriate class lettersymol.

8any e-tinguishers in current use are colour coded to indicate the type ofe-tinguisher. The o, colours are as follosJ

• /ater Gas Re

• Caron :io-ide >C2? #,+

• +oam C/e+6• :ry Poder #,e

+ire e-tinguishers used in or$shops and hangars should no e coloured Red.

It is hoe)er; unli$ely that e)eryone ill e using the ne colour cylinders for along time; so e aare of the old codes. 6ote the fire e-tinguishers picturedao)e use the colour coding.

1.3.3.1 W+te/ G+s F*/e Et*n0*s:e/s

These contain ater; anti0free=e and a caron dio-ide ottle. /hen the carondio-ide gas is released; the ater is e<ected through a no==le so that thetemperature of the fire is loered.

8aintenance Practices "1 y C"C Page %



1.3.3.2 C+/on D*o*e ;CO2< Et*n0*s:e/s

C2 is an inert gas that is stored in a cylinder under pressure. /hen it isreleased it e-pands and itDs temperature drops. It lan$ets the fire and e-cludeso-ygen; so the fire is e-tinguished. It is a)ailale in )arious si=es from smallhand held units to larger trolley mounted units. The state of charge is normallydetermined y eighing the cylinder and comparing itDs eight ith the eightstamped on the cylinder nec$. This e-tinguisher is most suitale for use on flightlines for engine starting; fuelling and general use. 8ay e a)ailale complete

ith )arious length hoses and application no==les for e-ternal use on a@cengines.

1.3.3.3 D/- Po=e/ Et*n0*s:e/s

:ry poder agents such as icaronate of soda; ammonium phosphate andpotassium icaronate are effecti)e against class "; C and : fires. /hen theagent is heated y the fire; caron dio-ide is released hich e-cludes o-ygenfrom the fire. The dry poder is propelled from the cylinder y a charge ofcompressed nitrogen. These e-tinguishers are particularly effecti)e on ra$efires; ecause they do not cool the ra$es as ould C2; foam or ater gas.

1.3.3.4 Fo+6 F*/e Et*n0*s:e/s+oam e-tinguishers are particularly effecti)e for li7uids such as fuel or oil fires.To chemicals are stored separately ithin a cylinder. /hen these chemicalsare mi-ed; a large )olume of foam under pressure is produced. This foam; hendirected onto the urning li7uid; lan$ets the fire and star)es it of o-ygen. Shouldnot e used for electrical fires.

1.3.3.5 F*/e #,+net

Stored in a R,: cylindrical container. #sually asestos or some other goodinsulator. &s itFs name suggests; it may e used to lan$et the flames.

1.3.4GENERAL PRECAUTIONS

The folloing general precautions should e oser)ed to minimise the ris$ offires and their affectJ

• Smo$e only in designated areas.

• ser)e and oey No S6o*n0 signs on flight lines.

• :o not carry matches or any other source of comustion.

• :o not ear studded or steel tipped footear.

• &ll flammale li7uids such as paint; dope; hydraulic fluid etc. should e stored

in an appro)ed store ots*e the hangar.

• Super)isors should ensure that all reasonale fire safety precautions areta$en and all fire apparatus is ser)iceale.

• Personnel engaged in maintenance should e fully con)ersant ith the useand operation of fire protection e7uipment. They should also $no the actionto e ta$en in the e)ent of a fire i.e. escape routes; fire alarms; position of fireappliances and assemly points.

• /hen fuelling a@c electricFs should not e sitched on or off.

• &ircraft should alays e onded hen eing or$ed on.

• /hen fuel tan$s are empty there is proaly a greater ris$ of fire than henthey are full.

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1.3.5PROCEDURE ON DISCO(ERING A FIRE IN THE WORK>PLACE

• S:ot ?F*/e? Lo,-.

• perate the nearest fire alarm or get someone else to.

• &ttempt to e-tinguish the fire ith the nearest suitale fire appliance. :o notattempt this if your actions ill endanger your on life or your chance ofescape.

• ,nsure fire rigade is called. Gi)e location of fire i.e. "uilding and position inuilding; also type of fire; +uel or ,lectrical etc.

• Close all doors and indos if possile >Reduce fire spreading?

• Proceed to assemly point.

1.3."ACTION TO #E TAKEN IN THE E(ENT OF ENGINE FIRES

• &ircraft engines are mostly susceptile to fires on start0up. The folloingpoints ill minimise the ris$ of damage due to an engine fire.

• &lays ha)e a fire e-tinguisher of the correct type a)ailale prior to startingthe engine. & C2 e-tinguisher should e close to hand for each engine

start.

• & safety person should e a)ailale; con)ersant ith the operation of the fireappliance and aircraft procedures.

• In the e)ent of a fire; the fuel supply and ignition should e turned o@@ eforeattempting to e-tinguish the flames.

• If possile see if the fire stops after fuel and ignition is cut. If not; applye-tinguisher agent )ia the fire access panels; do not run engines ithcolings open or remo)ed.

1.3.!ACTION TO #E TAKEN IN THE E(ENT OF #RAKE FIRES

"ra$e +ires occur mainly due to o)erheating after a hea)y landing or e-cessoperation of the ra$es. They may also e a result of a hydraulic fluid lea$ onto ahot ra$e. & ra$e unit may not catch fire immediately after an incident. The unitmay urst into flames a long time afterard a landing. Care should e ta$enapproaching a heel or ra$e unit. Nee/ approach in the direction of the a-le;alays approach in line ith the tyre i.e. from the front or rear of the aircraft.On,- attempt to e-tinguish a ra$e unit if it is on fire. If it is only o)erheated it isest left alone to cool. & :ry Poder e-tinguisher is the most effecti)e as it doesnot rapidly cool the unit. If a dry poder e-tinguisher is not a)ailale; a C2 or+oam e-tinguisher can e used y application of the e-tinguisher agent onto theGR#6: near to the unit. This ill allo the agent to arm up efore coming

into contact ith the ra$e unit.

1.4 THE NEED FOR SAFETY

It is fairly o)ious from the pre)ious comments that a maintenance engineerneeds to e oth $noledgeale concerning the safety re7uirements and alerthen or$ing around aircraft. (arious other factors ill also ha)e an effect on thele)el of safety. 9uman factors such as noise; lighting; fatigue and or$ pressuresare also rele)ant. Some of these ill e discussed in 8odule * 9uman +actors.

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1.5 WORKING AROUND AIRCRAFT

8any aspects of or$ing on aircraft ill e unsafe if the correct safetyprecautions are not oser)ed. ,)en al$ing around aircraft ill e dangerous ifyou are not aare of the dangers. Typical dangers ill e as follosJ

• Sharp o<ects such as proes; ing0tips; propellers; aerials

• /or$ing around engine inta$es and e-hausts is particularly dangerous>often fatal? hen the engines are running.

• /or$ing around propellers especially hen rotating.

• :amage to ears from constant e-posure to noise.

• 9igh pressure gases can cause e-plosions.

• /or$ing ith many tools; especially poer tools.

• /or$ing around electricity in general.

• 9ydraulically operated controls or other systems.

• :angers due to ris$ of fire.

This list could e e-tended consideraly. The safety aspect of or$ing aroundaircraft should e emphasised at all times. ,ngineers tend to ecome o)er0confident as e-perience increases. They should e alert at all times to thepossile dangers. &nyone ho has een in the a)iation maintenance usinessfor a reasonale time ill e ale to recount at least one instance of a seriousin<ury or fatality due to a safety related incident. &s$ your lecturerL




P+0e Intent*on+,,- #,+n




2. WORKSHOP PRACTICES

2.1 CARE USE OF TOOLS

In order to perform his duties competently and speedily; the 5icensed &ircraft8aintenance ,ngineer needs to pro)ide himself ith an ade7uate tool $it;maintain it properly and add to it as he progresses from one aircraft to another inthe pursuance of his career. It is o)ious; therefore; that $noledge of tools is an

essential part of his o)erall field of learning. In this topic e shall consider someaspects of the pro)ision and safe $eeping of oth personal tools and somespecial tools. The pro)ision of special tools is usually underta$en y theorganisation for hom the engineer or$s; ut their proper use and safe $eepingis )ery much the responsiility of those ho use them.

The care of tools; their correct usage and safe $eeping is an aspect of theengineers or$ hich must e approached ith the same degree of responsiilityas all other facets of his or$. /orn tools; e.g. spanners ith spread <as;scredri)ers ith incorrectly ground lades etc. ill damage the e7uipment onhich they are eing used; as ell as ris$ing in<ury to the user. To minimise theris$ of loose articles eing left on aircraft; many engineering organisations no

use FShado "oardsF for tool storage. & lac$ ooden oard carries paintedsilhouettes of all the tools attached y spring clips to that particular oard. &t theend of a particular period; a rief glance ill sho hich tools are still in use ofha)e not een returned to their storage. This method has contriuted )eryeffecti)ely to a reduction in the numer of accidents due to loose tools left inaircraft.

:espite some organisations using shado oards; many only use them forspecialist tools therefore in many companies the mechanic @ technician ill ee-pected to supply and control his on personal tool $it.

2.2 USE OF 'ATERIALS

8any different materials are used on aircraft and most of them need to eappro)ed for aircraft use. & fe e-amples of the different materials areJ

• Sheet metal; ri)ets and fasteners for repairs

• &dhesi)es; sealants and <ointing componds.

• Cleaning materials; these may e ater ased or sol)ent ased.

• Painting materials etch primers; thinners; paint and paint remo)ers.

• +uels; engine oil and hydraulic fluid.

• +luids for a )ariety of purposes including acids; al$aline fluids.

These and many more ill e discussed during the rest of the course. It is mostimportant for you to realise that many of the materials need special care to a)oidoth damage and in<ury. The maintenance or repair manuals ill alays specifythe recommended material for a specific tas$. Sometimes an alternati)e ill eidentified; ut if not so identified the recommended material must e used. ,achof the materials ill normally e identified y a part numer or identification code.This code numer may e a manufacturers code or an internationally standardcode. +or e-ample many aircraft sheet metal s$ins are made from an aluminiumalloy called durallumin. This may e coded 21%; 211% or 224; each eing aslightly different specification.




2.3 DI'ENSIONS

ne of the main tas$s an engineer has to perform is to identify if the aircraftconforms to its design specifications. 8uch of the maintenance or$ in)ol)escarrying out some form of inspection. This ill often in)ol)e measuring to chec$ ifdimensions are correct.

&n engineer ill e re7uired to ta$e measurements in a )ariety of differentcircumstances; using a )ariety of measuring de)ices. The folloing list gi)essome of the situations here a measurement may e madeJ

• 8easuring tyre tread depth to ascertain if tread ear is e-cessi)e

• Chec$ing the up and don mo)ement of a control surface this may in)ol)emeasurement of an angle or a dimension

• 8easurement of thic$ness of ra$e pads

• :etermining the dimensions of damage to aircraft structures

• 8easurement of the o)erall length of an electrical actuator

• 8easurement of the )olume of fuel during a fuel flo chec$

• &ccurate measurement of the dimensions of a hydraulic cylinder

In each of the pre)ious cases a different method of measurement may e used.In the first e-ample; a tyre depth gauge might e used. In the second themeasurement might e carried out ith a steel rule or a special tool supplied ythe aircraft manufacturer.

&ccuracy of :imensions

&s ell as using different types of measuring de)ice; the measurements mayneed to e carried out to a greater degree of accuracy. In all cases it is true tosay the dimension cannot e measured e-actly. It is only possile to measure to

the accuracy of the measuring de)ice used. &s ell as this; the measuring de)iceill not e totally accurate.

The scale of the rule shon is in millimetres; ith the smallest su0di)isionrepresenting mm. The line & is eteen 3mm and 3mm. Bou should notestimate the )alue of & as 33mm >or 34mm?. Its )alue can only e accuratelystated as 3mm. If you need to measure more accurately; you need to use amore accurate measuring de)ice such as a )ernier caliper.

&nother ay of gi)ing a false indication of the accuracy of a measurement ordimension is to specify too many decimal places in your measurement. +ore-ample; if you measure a dimension of 4inches ith a rule calirated in eightDsof an inch; you might e tempted to state the dimension as 4.12 as this is thedecimal )alue. This implies that you ha)e measured to an accuracy of .1rather than .




2.4 ALLOWANCES TOLERANCE

/hen components are manufactured; it is impossile for them to emanufactured to e-act dimensions. Part of the reason for this is much the sameas e ha)e already stated. The est accuracy e can achie)e is dictated y theaccuracy of our measuring de)ices. The aility of a machine to produce identicalparts also comes into play. & cutting tool ill ear and so ill produce slightlydifferent parts each time. If a part is rolled or e-truded; the rollers or die ill notproduce the same results each time. It is essential that components are

interchangeale so that they may fit together. The parts are therefore made to aspecified limit so that each may e slightly smaller or larger than the statedHnominal si=e. & to,e/+ne is the permitted )ariation tolerated and is a measureof the accuracy or st+n+/ o@ =o/6+ns:*7. If for e-ample a part should e2mm in diameter >nominal si=e?; it may e considered acceptale if it is ithinthe limits 2.2mm >high limit? and 24.*'mm >lo limit?. The difference eteenthe to limits is the tolerance; in this case .4mm. It is more difficult >and moree-pensi)e? to produce items ith )ery small tolerances. /e often use the termclose tolerance in this case. &ircraft components are usually manufactured tocloser tolerances than in other engineering applications.

The +,,o=+ne is considered hen e ha)e to mating parts such as a shaft

and a hole. The shaft is o)iously designed to fit into a hole. ,ach ill ha)e ahigh and a lo limit. The alloance is the difference eteen the high limit of theshaft and the lo limit of the hole.

2.5 CALI#RATION OF TOOLS E%UIP'ENT

Gauges and precision measuring instruments need to e chec$ed against aStandard (alue on a periodic asis to ensure accuracy ithin a gi)en range. If aparticular measuring de)ice is designed to e accurate to say .1; it ill notgi)e the re7uired accuracy if care is not ta$en hen it is used. It is also commonpractice to chec$ it e)ery time it is used to confirm itDs accuracy. & micrometerould; for e-ample e chec$ed for its =ero ready e)ery time it is used. It is not

alays essential for the de)ice to gi)e the e-act )alue as long as it is $non hoinaccurate the de)ice is. Precision gauges should normally e chec$ed and re0calirated at least e)ery si- months.

To/Be W/en: C+,*/+t*on G+0e

Tools and e7uipment re7uiring regular caliration chec$s ould includeJ




• 8icrometers oth e-ternal and internal

• (ernier measuring tools

• Tyre pressure gauges

• Tor7ue renches

• Cale tensiometers

• ,lectrical measuring gauges such as multi0meters

• Specialised 6on0:estructi)e e7uipment

• &)ionic Test e7uipment

/hen calirated; it is necessary to $eep a record to ensure that it is $non henthe e7uipment ill need re0caliration. /here necessary it should e identifiedho accurate the e7uipment is o)er the complete measuring range. Sometimes achart ill indicate ho much the instrument )aries from the stated )alue o)er thecomplete measuring range.




3. TOOLS

3.1 CO''ON HAND TOOLS

& good aircraft engineer ill most proaly ha)e a )ery e-tensi)e >ande-pensi)e? tool $it. Initially the tool$it ill e small and the engineer ill need toe selecti)e aout the numer of tools ought and their 7uality. The engineer illneed to e familiar ith many different types of tools. ther than a asic

$noledge pf the different types of tool and their use; it is necessary to descrieor Hclassify tools. "y this e mean ho to identify the different types of a tool.+or e-ample there are many different types of scredri)er. They differ oth in thetype of scres they are used on and in the si=e of the scredri)er. 8ost tools area)ailale in a )ariety of si=es and types. &t the )ery least the engineer ill needto e ale to descrie the tools hen it comes to uying them.

8aintenance Practices >C,? y C"CIssue 1 0 4 &pril 2

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S/e=/*e/s. Classified y length and type of lade e.g. 1M common; 'MPhillips; the lade eing made of alloy steel ith a ooden or plastic handle. In agood 7uality tool the lade ill e cold rolled to produce great strength andresistance to tist; and the tip drop forged and finally ground to the correctprofile. (ariations of the common or FstandardF scredri)er include Phillips;Posidri)e and Reed Prince; these eing the type ith a cruciform configurationlade >commonly termed FCross PointF?. It is important to select the correct typeof cross point dri)er for the particular scre in use; for although they may loo$ali$e at the first glance; the angles and shape of the cruciform slot are different.

In the case of the common scredri)er; for use on normal slotted scres; theor$ing tip of the lade should e ground flat to pre)ent slipping in the slot andthe tip should ottom in the slot. +urther )ariations of scredri)er includeRatchet; Pump0action; Changeale0tip >Snap0n? and stuy; this latter typeeing used in the restricted spaces fre7uently found in aircraft maintenance or$.


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P,*e/s. Classified y type of <a and o)erall length e.g. !M +ine 6ose; 'M SlideCutting; etc. 8ade of steel; forged to impart strength to their relati)ely light andslender form; ith the <as and side cutting section hardened. Care should eta$en to use only a pair of pliers capale of coping ith the <o in hand; since the <as can easily e tisted or damaged y mishandling. Specialised pliersinclude those for ire stripping; remo)al and fitting of circlips and ire loc$ing.


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H+66e/s. Classified y eight and type of head. The head is made of mediumcaron steel ith the or$ing faces hardened and tempered; hilst the eye forattachment of the handle is left soft. &fter long ser)ice a hammer may tend toecome unsafe due to small <agged pieces rea$ing off the edge of the stri$ingfaces. /hen this happens; the head should e discarded and a ne one fitted;ensuring that the steel retaining edge is secured in position. The head normallyhas one flat stri$ing face and one of a )ariety of shapes. The non flat face iscalled a Hpein. 9ence hen e classify a hammer e call it a all pein; crosspein or straight pein hammer. The flat surface is normally used for normal

stri$ing or hitting or$ such as ending a ar of metal or using a drift; hilst thepeins are used for specialised forming operations. /hen the use of a hammer isnecessary on finished surfaces; a soft hammer is used; the head consisting of adetachale plug of rahide; nylon or similar material. 5ead or copper heads arein use for similar reasons.


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F*,es. Proaly the most fre7uently used tool in the fitting trade; files areclassified according to their length; section; type and cut of teeth. The lengthdoes not include the tang. +iles are made of forged high caron steel; the tangon hich the handle is fitted eing reduced in hardness so that it is less rittlethan the or$ing part. The teeth of the file may e single or doule cut; hilst thegrade or tooth spacing may e classed as rough; astard; second0cut; smooth ordead smooth. These terms descrie the numer of teeth or FcutsF to the inch andthis ill )ary ith the length of the file. Representati)e figures for a 12M flat fileill eJ

"astard 21 cuts @ inch

Second Cut 2! cuts @ inch

Smooth 4 cuts @ inch

:ead Smooth %2 cuts @ inch


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Co66on,- se @*,es *n,e8

• F,+t. Parallel for most of itFs length; tapering in oth idth and thic$ness atthe end. :oule cut on oth faces; single cut on oth edges.

• H+n. Parallel in idth throughout itFs length; ut tapers in thic$ness at theend. :oule cut on oth faces; single cut on one edge; the other edge is leftun0cut and is $non as the FSafe ,dgeF. This is used for filing in corners

here one side is left untouched.• H+,@ Ron. :oule cut on flat face; single cut on cur)ed face. 6.". Cur)ed

face is not a full half circle in section. #sed in the formation of filed radii.

• T/*+n0,e o/ T:/ee SB+/e. 8ay e single or douled cut on all faces. #sedfor or$ on a$ard corners.


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P/e+t*ons s*n0 F*,es

• 6e)er use a file ithout a handle.

• 6e)er use a file as a le)er; since due to itFs rittle nature it may rea$ ith <agged pieces flying off >into eyesL?.

• /hen filing soft metal >&luminium; Copper?; the teeth end to clog. The fileshould e fre7uently cleaned y using a file card consisting of short ireristles on a faric ac$ing.


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C:*se,s. The engineers chisel is called a FCold ChiselF ecause they arespecially hardened and tempered for cutting cold metals. Consider there7uirements of a chisel. +irstly it must e harder than the metal it is cutting; andyet it must e tough and not rittle if it is to ithstand repeated hammer los.+or these reasons they are made from high caron steels or alloy steels heattreated to induce the properties that gi)e them a satisfactory or$ing life.Classified y length and section of or$ing lade. The most common types areflat; cross0cut; round nose and diamond0point. The angle of the cutting edge)aries ith the properties of the metal to e cut; e.g. a larger angle for tough and

hard materials; say ! 0 %N for steels; hile for cutting softer materials li$ealuminium a fairly sharp angle is needed; say 3N.

Typical uses for )arious shapes of chisels areJ

• F,+t. General fitting or$; chipping aay large areas prior to filing; remo)al ofri)et heads during repairs.

• C/oss t. +or cutting groo)es; $ey0ays on shafts and to di)ide up flatsurfaces into strips prior to cutting ith flat chisel.

• H+,@ Ron. +or cutting an oil groo)e in a earing.

• D*+6on Po*nt. +or cutting a hole in a plate; forming sharp corners; or for

mo)ing the centre of a drilled hole hich has started to run off0centre.

S/+7e/s. #sed for final surfacing or$ to correct slight arping and distortionand for lending out damage due to corrosion etc.; common types can e flat andhalf round. These can e locally produced y grinding a flat file ith a slightlycur)ed cutting edge and finished to a high degree of sharpness ith an oil stone.#sed in con<unction ith mar$ing fluid >e.g. engineers lue? and earing in mindthat the surface to e or$ed on must e )ery nearly true initially; a scraper cane a most useful addition to the aircraft engineers tool o-. +or instance; thehigh spot of a earing can e remo)ed and the correct fit of the shaft can eotained y scraping first the loer half; testing the fit ith mar$ing fluid ith theshaft in position; then repeating the operation on the top half.

H+s+=s. Classified y frame si=e and type >fi-ed; ad<ustale; tuular etc.?.The lade is tensioned y either tightening a ing nut or the handle itself.5engths )ary from appro-imately 'M 0 14M; fre7uently 1M and the lade ill emade from caron or alloy steel. 9ac$sas may also e fitted ith a round ladefor cutting in all directions >useful for cutting out damaged structure in sheetmetal?. #sually the lade teeth only ill e hardened; ut the lade may ehardened throughout. 6umer of teeth )ary; 1' T.P.I. >teeth per inch? eingsatisfactory for general cutting use; hile 3 T.P.I ould e preferale for cuttingthin sheet or tuing and 14 T.P.I. is suitale for cutting solid rass or copper. Themain cause of accidents to operators using hac$sas is lade rea$age;

resulting in hands coming sharply into contact ith the or$. "rea$age is usuallydue to either insufficient tightening of the lade; e-cessi)e donard pressure ore-cessi)e tisting of the lade on the forard stro$e. Special care is necessaryhen cutting thin sheet or tue; only a slightly donard pressure is re7uired.Note8 The lade is designed to cut only on the forard stro$e; ith the ladeinstalled correctly; i.e. teeth forard.


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S7+nne/s. These are a)ailale in a ide range of shapes and si=es and areintended for tightening or slac$ening a nut on a scre thread. Their length isrelated to the si=e of the nut for hich they are designed and any misuse >e.g.e-tending the length ith a tue? ill certainly result in damage to oth threadand spanner. Similarly; a hammer lo imparted to the end of the spanner tomo)e a stuorn nut ill also reduce the or$ing life of the spanner. Properlymaintained and used; ith a light smear of oil to protect their surface finish;spanners ill last for many years; and the practical engineer can ne)er ha)e toomany of them. Generally made from (anadium Steel; heat treated to pro)idehard; long lasting <as comined ith an e-tremely tough; resilient handle; thetraditional doule ended >i.e. open <a? type of spanner is the most common.The <as are usually set at 1N; 3N or !N to the shan$; so that for a relati)elysmall handle mo)ement a useful turning moment is attained at the nut simply yturning the spanner e)en hen or$ing space is limited.

The si=e of the spanner is clearly mar$ed at or near the <a and ill ee-pressed as a ".&. numer or a /hitorth; &.+. or 8etric si=e. Spannersintended for #nified threads ha)e their si=e mar$ed on the <a e-pressed as afigure correct to to decimal places; ut the decimal point is omitted e.g. ould e 1@2M across the flats; 2 ould represent 1@4M etc.

• R*n0 S7+nne/s. These ould e used in preference to open <a spannerssince they apply the load e7ually to all faces of the he-agon. In practice; mostmodern ring spanners ha)e a 12 point configuration to the head and arereferred to as i0he-agonal. This ma$es for greater )ersatility heremo)ement is restricted; permitting a nut to e turned hen only 3N ofmo)ement is possile.

• Co6*n+t*on S7+nne/s. These comine the est features of oth openspanners and ring spanners as they ha)e one head of each type; oth eingthe same si=e. The heads may e off0set to the handle and to each other;and in some cases the ring spanner may e deeply off0set to allo the headto e fitted to a nut in a shallo countersin$.

• Soet S7+nne/s. These are produced in to parts; i.e. the soc$et; placedo)er the nut or olt head and the handle hich is attached to the soc$et;usually y a s7uare dri)ing shaft. & ide )ariety of handles are a)ailale;such as FTF handle; ratchet; scredri)er grip and speed0handle >rather li$e acar heel race?. The s7uare dri)e; usually 1@4M; or 3@'M or 1@2M s7uareincorporates a spring loaded all hich engages in a groo)e in the soc$et.This should ensure that the soc$et lifts off the nut hen the operator ishesto reposition the soc$et on the nut; and pre)ents the soc$et ecomingdetached; possile in an a$ard position. Refinements to the asic soc$etand handle include e-tension rods to fit eteen the soc$et and handle;uni)ersal dri)e <oints; fle-ile rods; posidri)e it adapters; cros footattachments and con)erter adapters enaling one to use handles ith small

s7uare dri)es to connect to soc$ets ith large dri)es or )ice0)ersa. NoteJCare should e ta$en not to o)er tor7ue a soc$et hen using a handle ith alarge s7uare dri)e ith a soc$et ith a small s7uare dri)e. Soc$et sets area)ailale in all current si=e ranges and the practical engineer ill e ellad)ised to e7uip himself ith the est 7uality; most comprehensi)e set hecan afford. Cheap tools of inferior material ha)e )ery limited life and maydamage the component on hich it is eing used.

• A,,en Ke-s. Certain scres or olts ha)e a he-agonal recess in their heads. &n F&llen EeyF is used to tighten or slac$en the scres. The asic tool is ofhe-agonal cross section >to suit the recess? and is cran$ed through *N toform an F5F shape. They are made of hardened and tempered steel; toughenough to ithstand fracture and arasion @ ear. &llen $eys are also made

in straight lengths to fit into soc$et its. &llen $eys are classified y theirdimension across their he-agon flats.


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S7e*+, S7+nne/s. Included in this category are FCF spanners; Tor7ue Spanners;Peg Spanners etc. FCF spanners are used on round nuts; pipe connections etc.here the nut has a series of notches around itFs periphery. The spanner usuallyhas a cur)ed articulated arm ith a hoo$ on the end. This hoo$ is intended toengage into one of the notches on the nut. Peg spanners are similar e-cept thata peg >or to? engages on a hole in the edge or face of the nut.


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3.1.1'ARKING OUT TOOLS

In the asence of special <igs or fi-tures hich locate the or$ and pro)ide somemeans of guiding the cutting tool; most or$ necessitating remo)al of metalin)ol)es the scriing of guidance lines to indicate the positions of finishedsurfaces or the centre lines of holes. Some of the tools used are as follosJ

R,es. ,ngineering or$shop rules are used for general measuring and aremade from high caron steel suitaly hardened and tempered. They are usuallygraduated in Imperial and 8etric systems of measurement and classified y

length. Rules should e $ept free from rust and ne)er su<ected to rough usageor careless handling. The end of the rule in particular should e carefully treatedsince it generally forms the asis of one end of the measurement eing ta$en.ne common malpractice if the use of steel rules to de0urr sheet metal. Thismay not only damage the rule; ut it remo)es good metal from the sheet metal asell as the urr.

S/*e/s. Scriers are used for mar$ing guidance lines on the surface of or$Kthey are made of high caron steel; suitaly hardened and tempered and areclassified y length. Scrier points li$e those of di)iders; must e $ept $een andfine; and they should e fully protected hen not in use.

D**e/s F*tte/s SB+/e

D**e/s. :i)iders are used to set out distances and to scrie arcs and circles.

Their legs are made of high caron steel; hardened and tempered; ith a springsteel spring. :i)iders are classified y the length of the legs. The points shoulde $ept $een and of e7ual length; y stoning on the outside. Grinding; unlessdone )ery carefully ill change the temper of the points and render them soft./hen the di)iders are not in use; the points should e protected y stic$ing theminto a cor$.

F*tte/s SB+/es. +itters S7uares are used for setting out lines at right angles toan edge or surface; and for chec$ing right angular or$ for truth. S7uares aremade of high caron steel; hardened and tempered and are classified y thelength of the lade. The s7uare is made to )ery fine limits and this initialaccuracy must e preser)ed y careful handling and $eeping it in the o-pro)ided hen not in use.


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The lade and stoc$ ha)e their opposing edges ground truly parallel ith thelims set at e-actly *N to each other. This accuracy must e chec$ed from timeto time. This can e done y chec$ing the s7uare for truth against a masters7uare or against a ( 0 loc$. &n alternate test >see diagram to the right? is toplace the stoc$ against a flat surface; using the outside edge of the lade as aguide. The s7uare is then turned o)er and the outside of the lade chec$edagainst the line. The test should e repeated using the inside edge of the lade.

Co6*n+t*on Set. & comination set >see diagram elo? is )irtually three toolsin one; consisting of a lade or rule and three FheadsFK the lade is made fromhigh caron steel; hardened and tempered; hile the heads are of close0grainedcast iron. The lade is graduated in inch and metric scales; and a central groo)ealong itFs entire length accommodates a clamping scre fitted to each of theheads; thus enaling a head to e secured at any desired position along thelade.

The details of the three heads are as follosJ

• SB+/e He+. This head is pro)ided ith to or$ing faces; one at *N andthe other at 4N to the lade; thus enaling the tool to e used oth as a

s7uare and as a mitre. & spirit le)el is incorporated into the head and ascrier is pro)ided.

• Cent/e He+. This is used in con<unction ith the lade to locate the centreof a round ar or the centre line of a tue.

• P/ot/+to/ He+. #sed in con<unction ith the lade for chec$ing or settingup any angle up to 1'N. & spirit le)el is often incorporated.

C+,*7e/s. The types of calipers are as follosJ


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• Ins*e Ots*e. These are used in con<unction ith a rule or othermeasuring instrument for measuring distances eteen or o)er surfaces; orfor comparing dimensions. Inside calipers are used for measuring insidedimensions and outside for e-ternal dimensions. To set the calipers; setnearly to si=e y hand and then tap one leg >not at the point? to ma$e the finalad<ustment. /hen calipers are used for comparison purposes; the resultsotained largely depend on the sense of feel of the user.

• O Le0 C+,*7e/s. This tool is really half caliper and half di)iders. It may e

used for scriing lines parallel to an edge or for scriing arcs on cylindricalars to aid in finding the centre. These tools are often referred to as F<ennycalipersF.

'+/*n0 O@@ ;S/@+e< T+,e. #sed to support or$ for mar$ing out and to forma ase for measurements. 8ade from close grained cast iron; strongly ried forrigidity. The or$ing surface is accurately machined to gi)e a true; flat surfaceand s7uare edges. &fter use; the or$ing surface should e protected ith oiland the protecti)e co)er replaced. 6o or$ other than mar$ing or measurementshould e carried out on the tale.

S/@+e P,+te This may e used in place of the mar$ing out tale for relati)elysmall or$. It is much smaller than the tale and the finish is at least e7ual to

that found on a good tale. Surface plates are usually portale and used on aor$0ench. To test a flat surface for accuracy; the plate is smeared ithengineers lue and the surface to e tested rued on the plate. The amount ofmar$ing transferred ill indicate its flatness.

(ee #,os These are used on a mar$ing tale or surface plate to support roundor$. They are made of cast iron or case hardened mild steel; are supplied inidentical pairs; each unit of a pair eing stamped ith the same identification

numer. &ll surfaces are accurately machines and the (ee angle is e-actly *N.(ee loc$s are classified y the ma-imum diameter of the or$ hich can eheld. The clearance slot at the ase of the (ee allos o<ects to e set firmly.

S/**n0 #,os >see diagram elo?. & scriing loc$ is used to mar$ out linesparallel to a true surface; such as the or$ing surface of a mar$ing off tale or asurface plate. The accurately machines ase is made of cast iron; or case0hardened mild steel; the scrier is of high caron steel; hardened and temperedand the pillar angle; scrier height and angle are all ad<ustale. & finead<ustment is pro)ided for the pillar and doels in the ase can e pushed donso that lines can e scried parallel to the edge of the surface tale or plate.Scriing loc$s are classified y the height of the pillar.


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Ke->Se+t R,es These are sometimes termed Fo- s7uaresF; and are used formar$ing lines parallel to the a-is on the surface of tues and round ars. These

rules are usually graduated and are classified y their length.

Ke- Se+t R,e Use o@ Fee,e/ G+0es

Fee,e/ G+0es F+eelersF are used to measure small clearances or gapsK theyconsist of a series of thin fle-ile steel lades in graduated thic$ness )arying inmost cases from 1. to 1 or 2 thousandths of an inch. The lades are securedin a protecti)e metal scaard y a fulcrum pin and all lades not in actual useshould e ithdran into the scaard to pre)ent accidental distortion. +eelergauges are classified y the length of the lades. /hen not in use; the ladesshould e lightly smeared ith oil to pre)ent rusting.

Cent/e Pn:es & centre punch is used to ma$e a small indentation for locatingthe cutting edge of a drill at the start of a drilling operation. Centre punches aremade of high caron steel; the point eing hardened and tempered. & sharppoint should e maintained y careful grinding and should ha)e an angle of *Nfor general or$ or !N for light or$; such as mar$ing out. &utomatic centrepunches are a)ailale hich are spring loaded and simply re7uire pushing donto gi)e an indentation. The depth eing determined y the spring setting.


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Use o@ + Cent/e Pn:

E+67,es o@ '+/*n0>Ot Wo/There ill e many instances here it is necessary to faricate aircraft parts.Some of the s$ills re7uired in measuring out prior to farication of parts are

descried elo.

'+/*n0>o@@ Ret+n0,+/ Wo/ >"loc$s or sheet metal?

+ile one face of the metal true >chec$ ith steel rule or straight0edge? and s7uareone edge to the true faceK the or$ ill then stand firmly on the surface tale >orplate?. Parallel lines can then e scried across itFs face using a scriing loc$.If mar$ing sheet metal; the sheet can e placed against a (0loc$. 9eightmar$ing can also e carried out using a )ernier height gauge.

SB+/*n0 7 En o@ Ron #+/ o/ Te.

The diagram elo shos a simple method of mar$ing0off for s7uaring the end ofa ar. The ar or tue is supported in a pair of (0loc$s hich set it up parallel to

the tale and a third (0loc$ laid on its side pre)ents a-ial mo)ement. Thescrier is firmly clamped in the scriing loc$ at a height and angle hich ringsthe point in a suitale scriing position. The cutting line is then mar$ed yrotating the ar against the scrier point.

F*n*n0 Cent/e o@ Ro0: #+/


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pen out the legs of Fdd 5egF calipers until they are set at rather less than theradius of the ar. Scrie four short arcs on the end of the ar shon in thediagram >see diagram to the right?. The centre of the ar is then in the centre ofthe small figure. The position may e estimated y eye and centre popped.

'+/*n0>Ot > S66+/-

• nly oundary lines and cutting lines should e scried on 5ight &lloy sheet.Scried lines on this type of material may gi)e rise to crac$s. &ny lines otherthan cutting lines should e mar$ed ith a soft graphite pencil >all tracesshould e remo)ed afterards? or a a- crayon >not lac$ 0 it may containgraphite?.

• The points of scriers and di)iders must e $ept clean to produce )ery fine

scriing lines. Thic$ lines lead to inaccuracies.

• Scriing lines must e clear and distinctK prior to mar$ing out; it may ead)antageous to apply chal$ or hite ash to the surface. "right steelsurfaces should e coated ith copper sulphate or engineers lue.

• /hen the scrier is used in a scriing loc$; it must e clamped rigidly andscriing should e done firmly so that there is no necessity to retrace lines.The scrier point should e set as close as possile to the pillar; thusreducing the tendency of the point to hip.

• &lays trail the point hen using the scrier so that it does not dig in to thematerial.

&n accuracy of .1M is often accepted for mar$ing out although more accuracymay e otained using a )ernier height gauge.


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3.2 CO''ON POWER TOOLS

Sometimes hand tools are not practical for reasons of speed and accuracy. &)ariety of poer tools are used during aircraft maintenance. Cutting tools used inan aircraft en)ironment are generally pneumatically operated. ,lectrically dri)encutting tools ould e dangerous as they produce spar$s hich may ignite fuel)apours. The poer for the pneumatic tools is supplied )ia a compressor thatsupplies air at around ' p.s.i. The compressor normally incorporates a atertrap so that the air is as dry as possile. The air supply is normally supplied )ia

metal pipelines to a 7uic$ release coupling. The engineer ill normally connectthe poer tools to the coupling )ia a plastic or ruer fle-ile hose. 8anydifferent types of pneumatic poer tools are used; mainly y the airframe andengine engineers. The most common tools used are pneumatic >indy? drills;ri)etting hammers for solid ri)ets; lind ri)etting tools; pneumatic shears;pneumatic sanders; ri)et croppers and millers.

3.2.1ELECTRIC HAND DRILLS

>See diagram elo?. These may e dangerous to use unless they are $ept ingood condition and handled carefully.

1. &lays chec$ the condition of the lead and plug. :o not use the drill if it is

damaged in any ay.2. 8a$e sure the <o is firmly secured in a )ice or on the drill platform.

3. #se a luricant to $eep the point of the drill coolK $erosene is suitale for mostmetals.

4. :o not force feed or the drill may rea$.

. If sarf uilds up at the drill point; stop the machine efore attempting to clearit aay.

!. &lays ear goggles to protect your eyes.

E,et/* D/*,, D/*,, St+n

3.2.2PNEU'ATIC TOOLS

These are used mainly in structural repair or$.

A*/ O7e/+te ;W*n-< D/*,,s >see diagrams elo?. These are a)ailale in eitherstraight or pistol grip form. They ill; depending on si=e; accept drills up to 'mmdiameter. &ngled and off0set drills are pro)isioned for drilling holes in restricted

positions. These drills re7uire a separate collet for each si=e of drill.


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Rot+/- S+=. #sed primarily for cutting sheets of metal oth on and off aircraft.It may also e used for cutting plyood and plastic. The tool illustrated can cutsteel and alloy of thic$ness .'mm and 2mm respecti)ely.

Pne6+t* S:e+/s This tool is designed to cut sheet material up to 14 S/G inmild steel or 12 S/G in light alloy. Cutting is achie)ed y the action of areciprocating shear lade against a stationary an)il lade. Stellite tipped ladesare a)ailale for cutting stainless steel or titanium alloy.

Pne6+t* R*et*n0 H+66e/s. 8any types are a)ailale to suit a )ariety ofsolid ri)et si=es. They all operate on a similar principle as shon in the diagramelo. The air pressure supply controlled y the throttle utton or le)er; causesthe piston to oscillate rapidly ac$ards and forards in the arrel. The pistondeli)ers los to the ri)et )ia the interchangeale snap. &n ad<ustale airregulating scre )aries the ma-imum rate and poer of the gun. & typical rate is1; los per minute.

Pne6+t* #,*n R*ete/s. These are designed for easy forming of )arioustypes of lind ri)ets. There is usually a special ri)eter for each type of ri)et.Sometimes the ri)eter is air operated; ut many incorporate a hydraulicintensifier. 8any types e-ist; so only a selection is shon elo.


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'+n/e, C/o77*n0 Too,. The air operated cropping tool is used to cut off theprotruding mandrel stems of &)del ri)ets after they ha)e een set. The toolincorporates to cutting <as hich se)er the ri)et mandrel hen the control

utton is pressed. The cut mandrel ill still need to e milled don ith themilling tool; to gi)e a clean finish.


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R*et '*,,e/ . This air operated tool is used mainly for milling don protruding &)del ri)et mandrels. It usually has telescopic legs and a micrometer ad<ustmentto that the depth of cut can e accurately set.

3.2.3CARE OF AIR OPERATED TOOLS SAFETY PRECAUTIONS

/hen used; maintained and stored correctly; air operated tools ha)e a long andtroule free life. Their great enemies are lac$ of lurication and the entry ofmoisture and foreign particles introduced )ia the air supply. These effects can ereduced as follosJ

1. :rain the compressor oil and ater traps at least daily and more often if thetools are in prolonged use.

2. ,nsure that oth male and female parts of the air supply couplings are cleanefore connections are made.

3. "efore using a tool; introduce aout si- drops of the specified luricant intothe air supply opening.

4. "efore storage; carry out the oiling procedure again; operating the tool sloly

to distriute the oil.

The roaching action of most e-pansion ri)eting tools is dependent of the grip oftheir serrated <as. If the <as start to slip; stop ri)eting and clean out the <aassemly.

S+@et-. These tools should e perfectly safe during normal use ut they all cane dangerous if handled incorrectly or carelessly. "efore connecting a poertool to itFs supply; you should e aare of itFs potential dangers and plan ho toa)oid them. /arning notices often gi)e some indication of potential dangers andthey should e oeyed. ther precautions includeJ

• Eeep your hands; hair and clothing clear of the mo)ing parts of tools.

• /ear goggles; ear defenders and protecti)e clothing as the circumstancesdemand.

• :o not lea)e an unused tool connected to the poer supply.

• &lays operate ri)eting hammers against a resistance; especially hentesting itFs action.

Note. 8ost accidents occur due to ine-perienced operators fooling around ithpoer tools.


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3.3 PRECISION 'EASURING TOOLS

In order to achie)e the accuracy re7uired in many aircraft engineeringapplications; it ill e necessary to use e7uipment capale of measuring to agreater degree of accuracy than a steel rule. The maintenance manual illspecify the dimensions to e measured. In many instances; an accuracy of.1 >one thousandth of an inch?; .1 mm >one hundredth of a millimeter? orgreater ill e specified. Precision measuring instruments are used to achie)ethis o<ecti)e. It is necessary for all engineers to e familiar ith their use and e

ale to measure ith them to the re7uired degree of accuracy.

3.3.1'ICRO'ETERS

8icrometers are used for measuring oth internal and e-ternal dimension to anormal accuracy of .1 or .1mm. In the Imperial micrometer shon; thespindle and arrel threads ha)e a pitch of .2 >4 threads per inch?; thereforeone complete turn of the spindle and slee)e ill ad)ance the spindle y .2 or2 thousandths of an inch. The slee)e is su0di)ided into 2 e7ual di)isions andso rotation of the slee)e y one di)ision ill mo)e the spindle .2@2 O .1or ne thousandth of an inch.

& metric micrometer uses the same principle e-cept that the thread pitch is

.mm and the slee)e is di)ided into e7ual di)isions. 8o)ement of one slee)edi)ision is therefore e7ual to .@ O .1mm.

The diagram elo shos an e-ample of a micrometer reading made up ofJ6umer of main di)isions on the arrel 2 O .26umer of smaller di)isions of .2 each 1 O .2Thimle di)isions >coinciding ith a-is line? ! O .!

Tot+, Re+*n0 O .231


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3.3.1.1 (e/n*e/ 6*/o6ete/s

The degree of accuracy of a micrometer can e further impro)ed y adding a)ernier scale as shon ao)e right. This type of imperial micrometer has anaccuracy of .1 or one ten thousandth of an inch. The thimle is graduatedinto 2 di)isions as efore and 2 half di)isions. & )ernier scale is then engra)edon the arrel. The line on the )ernier scale that coincides ith a line on theslee)e gi)es the final accuracy. In the e-ample shon ao)eJ

6umer of main di)isions on the arrel ............ 4 O .44 6umer of smaller di)isions of .2MM each ........ 2 O .2 Thimle di)isions >coinciding ith a-is line? ...... 1* O .1*+urther half di)ision on the thimle 1 O .Coinciding (ernier line +our 4 O .4

Tot+, /e+*n0 O ).4"&&

ther gauges of the micrometer type are in use as precision measuringinstruments. Some are descried as follosJ

3.3.1.2 Inte/n+, '*/o6ete/

This instrument has asimilar scale to thee-ternal micrometer; utas the name suggests; itis used for measuringinternal dimensions iththe same accuracy. Themicrometer may e usedfor a range ofmeasurements y fittingfi-ed length e-tensionpieces.


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3.3.1.3 De7t: '*/o6ete/

This is used to measure the depthrelati)e to the ase plate hich isground and s7uare to the spindlea-is. The scale ill e =ero hen theend of the spindle is flush ith thease.

3.3.1.4 T:/ee Po*nt Inte/n+, 6*/o6ete/

This is used to gi)e more accuracy to internal measurement of ores. Thestandard internal micrometer might not e s7uare and therefore not e at theoreFs idest part. The three symmetrically positioned an)ils of this micrometer

ensures an accurate reading.

3.3.2USING 'ICRO'ETERS

The main scale of an imperial micrometer is one inch long; and so e-ternalmicrometers are a)ailale in a )ariety of si=es. The standard si=e is 01; ut 102; 203 and so on are a)ailale to measure larger e-ternal si=es. &s e-plainedpre)iously; accurate e-tension pieces are a)ailale for the internal micrometers."efore using an e-ternal micrometer; the =ero reading should e chec$ed. This isdone ith the 0 1 instrument y closing it right up and chec$ing the on thethimle is in line ith the a-is. & machined distance piece is inserted in the largersi=es to chec$ for their =ero. &ccuracy depends on cleanlinessK oth of theinstrument and the component you are measuring. 8icrometers may e fittedith a ratchet so that a uniform result may e otained.

&d<ustment of the =ero setting may e achie)ed y mo)ing the arrel ithin theframe ith a HC spanner; or y ad<usting the an)il. Compensation for ear of thethread is often a)ailale y ha)ing a tapered thread on the arrel scre threadthat can e ad<usted for tightness.


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3.3.3(ERNIER 'EASURING INSTRU'ENTS

8any measuring instruments use the )ernier principle. ne of the most commoneing the (ernier Caliper shon elo. The instrument consists of a eam onhich is mar$ed a main scale; similar to that of a steel rule. There are to <as;one of hich is integral ith the main scale. The other <a slides along the mainscale and has the )ernier scale mounted on it. The mo)ale <a is alsoconnected to a clamping de)ice >termed the fine ad<ustment clipper?. This shoulde loc$ed at the appro-imate measurement and final ad<ustment made ith the

fine ad<ustment scre. &fter setting; the <a loc$ing scre should e used toensure an accurate reading is otained. +or measurement of internal dimensions;some calipers ha)e MnisM. The idth of oth of the nis is usually mar$ed on oneof the nis and this dimension should e added to the reading otained. Somecalipers ha)e MTargetsM or small indentations; from hich di)iders may eaccurately set. "efore using the calipers; they should e chec$ed for =ero; yclosing them up and chec$ing the =ero line on the main scale coincides ith the=ero on the )ernier scale.

3.3.3.1 Re+*n0 t:e 'et/* (e/n*e/ S+,e

n the top metric scale; the distance from to 1 is 1 mm. This is di)ided into 1parts >1 mm?. ,ach mm is further di)ided into to >.mm?. The loer slidingscale has 2 di)isions and gi)es us an accuracy of .@2 O .2 mm.


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Refer to the diagram elo and follo the steps to determine the reading of themetric )ernier caliper.

#pper scale reading coinciding ith the on the sliding scale is 3.

The 14 mar$ on the sliding scale e-actly coincides ith a mar$

on the upper scale. This represents 14 - .2 mm .2'

Total Reading O 3.%' mm

3.3.3.2 Re+*n0 t:e I67e/*+, (e/n*e/ S+,e

n the top scale; 1 is di)ided into 1 parts and each part is further di)ided intofour parts. ,ach di)ision has a length of of 1@1 O 1@4 O .2. n the loersliding scale there are 2 di)isions and this gi)es us our accuracy of .2@2 O.1

In the e-ample shon an upper scale reading coinciding ith the

on the sliding scale is 3.%

The 11 mar$ on the sliding scale e-actly coincides ith a mar$

on the upper scale. This represents 11 - .1 .11

Total Reading O 3.'!


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3.3.3.3 (e/n*e/ He*0:t G+0e

This instrument is used in con<unction ith a surface tale or surface plate. It illpro)ide a method of accurate measurement from the surface tale to the mo)ing <a. It may also e used to scrie or mar$ metal cut lines hen used ith a )eeloc$ or other s7uare or$.

(e/n*e/ P/ot/+to/

This is used to ta$e angular measurements and consists of a solid ase or stoc$;ith an ad<ustale straight edge attachment hich can e set at an angle relati)eto the ase. &ngular mo)ement of the straight0edge rotates a disc on hich is

mounted a circular protractor scale graduated in degrees. This scale is read incon<unction ith a )ernier scale hich gi)es an o)erall accuracy of minutes orD.

3.3.3.4 D*+, G+0es ;D*+, Test In*+to/<

This measuring instrument may e used to gauge the depth of dents or surfacedamage relati)e to the normal surface. It ould e typically used to ascertaindepth of corrosion on air aircraft s$in panel. It may also e used to chec$ forde)iation of a cran$shaft etc. The gauge is usually clamped rigidly in a stand anda =ero reading otained ith reference to a neutral point. If chec$ing )aluesaout a mean; the gauge should e pre0loaded more than one dial re)olution and

then the outside dial rotated to set the instrument to =ero.


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There are to types of:TI instruments incommon useJ

P,n0e/ t-7e

&n e-ample of this typeis shon. & gear train isused to magnify thedisplacement of theplunger; and the

magnitude of itFsdisplacement is indicatedy the pointer and scale.The small pointer countsthe numer of completere)olutions made y themain pointer.

Lee/ T-7e

In t:*s t-7e + le)er andscroll is used to magnifythe displacement of the

stylus. This type ofinstrument has a limitedrange compared ith theplunger type. 9oe)er itis more compact and thescale and pointer aremore easily read.


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LU#RICATION

The lurication of an aircraft and its component parts; is one of the mostimportant aspects of aircraft ser)icing. It must e carried out regularly; and toprescried schedules; in order to reduce friction eteen mo)ing parts and tominimise the ris$ of component failure.

3.3.4PURPOSE

/hen to parts are mo)ing in relation to each other; particularly hen they arehea)ily loaded; the friction eteen them ill generated heat. & luricant appliedeteen the to surfaces ill pro)ide more than one function. It illJ

• separate the to surfaces and thus reduce the friction.

• help dissipate the heat uilt up due to the friction

• form an anti0corrosi)e arrier

There are many; and )aried lurication tas$s; ranging from a simple access panelhinge re7uiring lurication ith light oil; to a heel earing on hich a highmelting point grease is used. & ide range of luricants is needed to satisfy the

re7uirements of modern aircraft. The luricant ill normally e oil or grease; utthere are many specialised forms of oils or greases.

3.3.5OIL

There are three main types of oil J

• '*ne/+, O*, is refined from crude oil

• (e0et+,e O*, is manufactured from )egetale ased products e.g. Rapeseed >:uc$hams?

• S-nt:et* O*, 8ay e mineral or )egetale ased; ut does not fit intospecifications for the other types.

3.3."GREASES

These normally consist of a petroleum ase oil thic$ened ith gelling agents andmodified y filling agents. Typical gelling agents are Sodium or lithium hich areused in high temperature greases; &luminium gi)es a grease adhesi)e propertiesand Calcium gi)e ater resistance. Typical applications for grease ould eheel earings; ,ngine and flying control <oints; uni)ersal <oints and screthreads. Grease may e used instead of oil for the folloing reasonsJ

• 5ess prone to lea$ing out of the component.

• They generally gi)e etter protection.

• 5onger lasting.

3.3.!LI'ITATION OF OILS AND GREASES

6o one oil or grease ill e suitale for all purposes. &n oil may e used toluricate the mo)ing parts of an internal comustion engine and due to thespecific re7uirements for this use; it ould ha)e properties to suit the loading andoperating temperature. It may e completely unsuitale for lurication of a flapscre <ac$ or as a heel earing luricant. The folloing points should econsidered concerning choice of oils or greases.


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(*sos*t-

This is the term used to determine the thic$ness of the oil or itDs resistance toflo. & thin oil ill ha)e a lo numer and a thic$ oil; a high numer. &eroshell 'for e-ample is thinner than &eroshell 1.

Te67e/+t/e E@@et

&n increase in temperature ill reduce the )iscosity of an oil. & thic$ or high)iscosity oil may protect hea)ily loaded parts hen it is arm and circulating./hen cold; the oil may not flo and oil star)ation may cause premature failure.

O*, A*t*es

These are sustances hich are added in small 7uantities to impro)e theproperties of the oil. The oil may contain one or more additi)es such asJ

• Dete/0ents They enale the oil to hold sludge in suspension and gi)e acleaner system.

• Et/e6e P/ess/e ;E.P.< #sed in hea)ily loaded gear trains e.g. helicoptergearo-es.

• Ant*>Co//os*e Reduces the corrosi)e effects of acids in oil.

'et:os o@ A77,*+t*onThere are a numer of different methods of luricating aircraft components.5urication may e carried out efore assemly of a component; or duringmaintenance. It is essential that the correct luricant and the correct method ofapplication is used for e)ery lurication tas$. The asic methods used areJ

• O*, C+n 5uricating oil is commonly applied y the use of an oil can. Someparts ha)e oil0ays machined into them; hilst others rely on application ofoil directly to the mo)ing parts.

• P/e>7+*n0 8any earings and similar parts are luricated ith greaseand sealed during manufacture. The luricant pac$ed into the earing is

sufficient for itDs or$ing life; and no further lurication should e re7uired.• G/e+se Gns Greasing is normally carried out ith a hand operated

grease gun hich in<ects grease into earings and <oints under pressure.Parts luricated this ay ha)e special nipples hich permit pressurisedgrease to pass directly to the earing surfaces. The correct amount of greaseis normally shon y ne grease coming out of the earing. It is importantthat the e-cess grease is cleaned off; to a)oid dirt eing collected y thegrease and therey introduced into the earing surface.

• H+n 5urication may e carried out y smearing oil or grease directly ontothe earing surfaces y hand.

3.3.$LU#RICATION CHARTS

These are often used in the 8aintenance 8anual to indicate aircraft partsre7uiring lurication. &s can e seen in the folloing diagrams; symols used onthe chart may indicate the fre7uency lurication is re7uired; the type of luricantre7uired and the method of application. &lternati)e luricant specification codenumers are often gi)en. &lternati)es are sometimes gi)en in handoo$spulished y the ma<or oil suppliers such as Shell; 8oil etc. The diagrams onthe folloing pages illustrate the use of charts in aircraft 8aintenance 8anuals.


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4. ENGINEERING DRAWING

The incorporation of a repair scheme or modification on an aircraft usuallydemands that the engineer responsile should or$ to re7uirements laid don inengineering draing; or; e)en more fre7uently; in a series of draings. Thedraing can therefore e said to contain information hich the draing office andstress engineers ish to impart in other that the or$ done on the aircraft shall ecarried out correctly and ithout possiility of misrepresentation.

& good engineering draing should therefore con)ey its message clearly; simplyand ithout amiguity. :imensions must e easy to read and the scale usedmust e clearly indicated. 5imits and fits; materials specification; surface finishetc. must e 7uoted for each item; here necessary; to hich the draing refers.

The production of engineering draings is a highly specialised tas$ ith manycon)entions that must e clearly understood if the draings are to e interpretedcorrectly. In this respect it should e appreciated that these notes are intendedas a guide to the interpretation of draings and not to their production.

At:o/*t- @o/ t:e D/+=*n0

Ci)il aircraft manufactured in the #E are constructed of parts and components

manufactured in compliance ith appro)ed draings. To ensure correctness andsuitaility of design; appro)ed draings and associated documents must eproduced y a :esign rganisation appro)ed y the C&& in accordance ithSection & of "C&R.

Section & further descries that all calculations on hich the airorthiness of theaircraft depends; must e independently chec$ed; thus the design draing itselfis su<ect to a system of inspection as are the parts produced to its re7uirements.

The appro)ed Inspection rganisation or the Certifying ,ngineer should ensurethat the draings are appro)ed and that the parts are correct to these draingsand associated documents. &ny de)iation from the draings and theirassociated documents must e co)ered y a suitale concession procedure as

gi)en in C&P !2.

8ost appro)ed design organisations no or$ in accordance ith "S3'J1*'4hich standardises the are)iations; symols and con)entions used inengineering draing; and these notes ha)e een ritten in conformity ith thatstandard.

D/+=*n0 Pen*,s 7ens

:raings are made using pencils or specialised pens. The 29 grade pencil isgenerally used for thin line or$; dimensions; centre lines; hidden detail etc. the9 grade is used for thic$ line or$; )isile outlines etc. The 9" grade is used forlettering; numerals and s$etching. 9 grades of lead are hard. " grades soft.

Specialist pens are a)ailale in thic$ness of .%mm >thic$ lines? and .3mm >thinlines?.

4.1 DRAWING TYPES

:raings may e di)ided into main categoriesJ

• :etail

• Su0assemly

• 8ain assemly

• Installation

• General arrangement


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,ach set of draings generally contains a schedule of parts in)ol)ed. Thus; thecomplete set of draings and any associated documents >referred in thedraings? present a complete record of information re7uired to manufacture andassemly e)ery part of an aircraft. Such draings also form part of the completeinspection record.

/here a component consists of a numer of items fitted together; it may often eimpractical to dra all the items on one sheet of paper. Se)eral sheets may ha)eto e used to sho all the items concerned and three main types of draings ille found on those sheets.

• Det+*, D/+=*n0. This type of draing shos one item or detail only. Thistype of draing shos all the information necessary for the item to emanufactured. It ill contain information such as material specification; heattreatment; surface finish and all dimensional information re7uired. There mayalso e cross0references to other draings or documents necessary in themanufacture process.

• Asse6,- D/+=*n0. This type of draing shos to or more items or detailsfitted together to form an assemly. It ill not contain dimensions or otherdetails of the indi)idual items. It ill contain instructions necessary toassemle the items. These instructions may include special treatments

re7uired. The assemly draing ill refer to the indi)idual parts y partnumer or draing numer.

• Gene/+, A//+n0e6ent. This type of draing; fre7uently referred to as a G&;shos a complete component and can e said to sho a numer ofassemlies fitted together. The folloing diagram >F G& &ssemly of 5e)erand "rac$etF? is a draing hich shos not only the assemlies and theirrelationship to each other; ut also any instructions to e folloed duringassemly and dimensional chec$s afterards. Some standard items areused in this G& and these are again referred to y part numers only.


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4.1.1NOTES ON DRAWING

Re,+t*ons:*7 #et=een D/+=*n0s. &s a complete component often re7uiresse)eral detail and assemly draings for its production; it is necessary to ensurethat all draings are connected y a system of cross0referencing. This ensuresthat the draings for all the details hich comprise an assemly; and for all theassemlies hich comprise the G&; can e otained y direct reference to thedraings.

In@o/6+t*on o@ t:e GA. ,ach G& must ha)e its on indi)idual draing numerfor identification purposes; and also a title. & schedule of the assemlies thatma$e up the G& must e pro)ided; either on the G& itself or on a separate sheethich must e identified y cross reference ith the G&.

It is common practice to numer the assemlies consecuti)ely on the schedule;and to repeat the numers on the G& Mdoule alloonsM hich are connected yMleader linesM to the assemlies concerned. :etail parts ha)e their referencenumers in Msingle alloonsM. :oule and single alloons are used in thepre)ious diagram MGeneral &ssemly of 5e)er and "rac$etM.

In@o/6+t*on on t:e Asse6,- D/+=*n0. ,ach assemly draing; <ust li$e theG&; must ha)e its on indi)idual draing numer and also a title. & schedule ofthe details hich comprise the assemly must e pro)ided; either on theassemly draing itself or on a cross0referenced separate sheet.

It is again common practice to numer each detail consecuti)ely in the schedule;and to repeat the numers on the assemly draing in single alloons hich areconnect to the details concerned y leader lines. This is shon in the pre)iousdiagram M&ssemly of "rac$et and "ushM and M&ssemly of 5e)er and SpindleM.The assemly draing must also carry a cross reference to the G& of thecomplete component.

In@o/6+t*on o@ t:e Det+*, D/+=*n0. &s a detail in a single item hich cannot efurther sudi)ided; a schedule is not necessary on a detail draing. The

information of the draing ill include its on indi)idual draing numer; title anda cross reference to the assemly draing on hich the detail appears.

P+/t N6e/ . In some cases the draing numer of a detail; assemly or G&; isused as a part numer for the item concerned. If the part numer is differentfrom the draing numer; it must e 7uoted on the appropriate draing.

T:e A77/o+, o@ + D/+=*n0. The regulations prescrie that all design or$carried out on an aircraft must e produced y an appro)ed design organisation.:uring the design stage of a modification or repair scheme the or$ ill;therefore; e chec$ed; stresses calculated and final appro)al gi)en y aresponsile person; usually the Chief :raughtsman. It is therefore )ital to ensurethat all draings are chec$ed for appro)al efore they are used to carry out or$

on an aircraft. This appro)al is stipulated on all draings used in this section.

4.2 SY'#OLS

The ad)antages of using symols areJ

• The use of symols and o-es eliminates lengthy descripti)e notes.

• Symols are international.

• "rief and precise.

• ne type of Geometric Tolerance can control another.


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4.2.1WELDING SY'#OLS

These are used on a draing to mar$ and identify the position and type of a eld. &ll elding terms and symols are contained in "S4**. The folloing noteshighlight the methods used to represent the difference types of elding <oint.

T:e We,*n0 S*0n. The features of a elding sign areJ

• &n arro hich normally points to the position of the eld.

• & reference line; ao)e or elo hich is placed.

• & elding symol hich indicates the types and position of the eld.

De@*n*t*ons +n Inte/7/et+t*ons.

• The side to hich the arro points is termed the Farro sideF.

• The side opposite the arro side is termed the Fouter sideF.

• The eld symol indicates the type of eld and it is importance to notehether it is placed ao)e or elo the reference line.

• If the eld symol is suspended from the reference line; the eld is made onthe arro side of the <oint.

• If the eld symol is placed on top of the reference line the eld is made onthe other side.

• If the eld symol is on oth sides of the reference line then the elds aremade on oth sides of the <oint.


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4.2.2SURFACE FINISH

& controlled surface te-ture is necessary on many aircraft components not onlyon mating surfaces; ut also on e-terior surfaces. Structural parts made fromhigh tensile steel and high strength alloys; re7uire the smoothest possile finishto impro)e resistance to fatigue failure and corrosion.

Surface te-ture is defined as those irregularities; ith regular or irregular spacing;hich tends to form a pattern on the surface. &lthough a surface may appearsmooth; hen magnified it can e seen to form a series of pea$s and )alleys.

The method hich has een adopted internationally as the standard means ofgrading surface te-ture is $non as the arithmetical mean de)iation and istermed the Ra parameter. R& represents the a)erage roughness of the surfaceo)er a gi)en sampling length.

The R& )alue may e determined y electrical proes or y graphicalassessment.

Ra >µ m? O

here (m O )ertical magnification of scale

The surface te-ture re7uired is e-pressed in µ m >micro metres? using one of thefolloing symols >this is not a comprehensi)e list and is only pro)ided as an

e-ample?.


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4.2.3STANDARD CON(ENTIONS

The folloing are a selection of the )arious types of lines in current useJ


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Conent*on+, Re7/esent+t*on o@ Co66on Fe+t/es. ne ay of reducing thetime to produce and interpret draings is to use con)entional symols for detailshich occur fre7uently. /hen users of draings understand the meanings ofthese symols; the draings themsel)es are often much easier to read ecausethey are not cluttered y tedious detail. The diagram elo illustrates some ofthe most common features encountered on aircraft draings.


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A##RE(IATIONS

In addition to symols; are)iations are fre7uently used in ,ngineering:raings; a fe of the most common and their meanings are as follosJ

Te/6 A/e*+t*ono/ s-6o,

Te/6 A/e*+t*ono/ s-6o,

&cross flats &@+ 6umer 6.

&ssemly &SSB Pattern numer P&TT 6.

Centres CRS Pitch circle diameter PC:

Centre line 5 or C5 Pneumatic P6,#

Chamfered C9&8 Radius >in a note? R&:

Cheese head C9 9: Radius >preceding a dimension? R

Countersun$ CSE Re7uired R,Q:

Countersun$ head CSE 9: Right hand R9

Counterore CF"R, Round head R: 9:

Cylinder or cylindrical CB5 Screed SCR

:iameter >in a note? :I& Sheet S9

:iameter >preceding a dimension?... S$etch SE

:raing :RG Specification SP,C

,-ternal ,TSpherical diameter >preceding adimension?

SP9,R,

+igure +IGSpherical radius >preceding adimension?

SP9,R, R

9e-agon 9, Spotface SF+&C,

9e-agon head 9, 9: S7uare >in a note? SQ

9ydraulic 9B: S7uare >preceding a dimension?......

Insulated or insulation I6S#5 Standard ST:

Internal I6T #ndercut #FC#T

5eft hand 59 (olume (5

5ong 5G /eight /T

8aterial 8&T5 Taper; on diameter or idth

8a-imum 8&

8inimum 8I6

4.3 DI'ENSIONS


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,ach dimension re7uired for the complete manufacture of an engineering part isgi)en on the draing; and to a)oid confusion; appears once only. ,ach is adirect measurement and not one that has to e or$ed out y the addition orsutraction of others. /here possile; the thin dimension lines are placedoutside the actual outline of the o<ect. To do this; thin lines are pro<ected fromthe particular points and surfaces; and the dimension lines dran eteen them.Small arroheads at the ends of each dimension line touch each of the pro<ectedlines to sho precisely here the dimension applies.

/here a numer of dimensions are to e gi)en from a common datum surface;line or point; one of the methods shon in the diagram elo should e used.The normal method should e used here)er practicale. There are instances;hoe)er; here the alternati)e method has definite ad)antages; e.g. herespace is restricted. /here the alternati)e method is used; a large dot should eplaced centrally on the datum line. In oth methods it adds clarity to the draingif the dimensions are placed near the appropriate arrohead.

Chain dimensioning should only e used here the possile accumulation oftolerances does not endanger the functional re7uirements of the part >seediagram elo?


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4.3.1LEADER PROECTION DI'ENSIONING LINES

5eader lines are used to point to parts re7uiring identification.They are terminated in a dot if hole part is su<ect to e descriedsuch as part numer; if the surface is su<ect matter thetermination is an arro head. >If the leader line ends on dimensionline termination is ithout arro dot?. Pro<ection lines are dran as

an e-tension from the part to enale identification of distance to edimensioned. & gap is alays left eteen the component andpro<ection line. :imension lines are used to gi)e the length offeature indicated. They are ne)er ro$en e)en if item isFforeshortenedF; smallest are shon nearest to the outline. &rroheads are normally shon inside the limits of the dimension; uthere space dictates may e shon outside.

4.3.2REDUNDANT DI'ENSIONS

/here an o)erall dimension is shon >as in the diagram elo? one of theintermediate distances is redundant and should not e dimensioned. ,-ception

may e made here redundant dimensions ould pro)ide useful information; inhich case they should e gi)en as Fau-iliaryF dimensions. /here all theintermediate dimensions are shon; the o)erall distance should generally egi)en as an au-iliary dimension >see oth diagrams elo?.

&u-iliary dimensions should not e toleranced ut should e included inparentheses >.? as in the diagrams elo. &u-iliary dimensions do not go)ernacceptance of the product.

The figures used to denote each dimension ill normally appear; in millimetres orinches; eside the appropriate dimension or leader line. &ll figures arepositioned so that they can e read from the ottom on the right0hand side of thedraing. Some e-amples of ho dimensions should e shon are gi)en eloJ

• Si-ty0one and a half millimetres 0 !1.mm

• 9alf a millimetre 0 .mm• Tel)e Thousand; Three 9undred millimetres 0 12 3mm


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• +i)e and Three Quarter inches 0 UM or .%M

• To feet; half an inch 0 2F0VM or 2F0.

4.3.3HOLES RADII

Complete circles are alays dimensioned y their diameter. Conse7uently; adimension indicating the diameter of a hole of a cylinder ore; is alays precededy the diameter symol . The precise position of a hole is located y to centrelines; and a dimension indicating the distance eteen holes is alays measuredfrom the hole centre. Small arcs; such as those formed y rounded edges andfillet radii; are dimensioned y leader lines; the actual si=e of the radius eingpreceded y the letter FRF as shon in the diagram elo.

4.3.4ANGLES CHA'FERS

&lthough the radian is the preferred SI unit; angular dimensions on engineeringdraings are shon as degrees; minutes and seconds. They appear; fore-ample; asJ 22N3F; N1F3M. The diagram elo shos ho these angulardimensions and the usual 4N chamfers are indicated.


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4.4 TOLERANCE

4.4.1LI'ITS AND TOLERANCES

It is the aim of modern engineering production methods to ma$e parts siftly andto an acceptale degree of accuracy. 6o engineering component can e made;or needs to e made; e-actly to si=e. "y using high 7uality machine tools and acertain fle-iility in dimensions; parts can e made at a tremendous rate and atthe same time e guaranteed to e fully interchangeale. This is done y

adopting a system of limits hich; in practice; defines ho much igger orsmaller than the asic si=e an item can e and yet still e considered acceptale.,-amples of ho a asic linear dimension of 2mm might appear as shoneloJ

The e-amples sho that; although ideally the re7uired si=e is 2mm in practice;pro)ided that its actual si=e falls eteen the e-tremes shon; the item isacceptale. The upper dimension is the ma-imum permitted si=e of the F9igh5imitF and the loer dimension if the ma-imum of the F5o 5imitF. The differenceeteen these high and lo limits of si=e is called the FtoleranceF.

n engineering draings; each dimension may e indi)idually toleranced; thelimiting dimension eing shon either as to dimensions or as a single

dimension plus or minus a tolerance >see diagram elo?. /hen an o)erallgeneral tolerance is applied to the ma<ority of dimensions; a general note to thiseffect is used.

4.4.2GEO'ETRIC TOLERANCE

/e ha)e already co)ered dimensional tolerance >i.e. si=e? hoe)er; there arecircumstances hen this is not sufficiently precise to control form; attitude andlocation.

Geometric tolerance is defined as the ma-imum permissile o)erall )ariation ofform; or position. To eliminate the need for descripti)e notes geometric

tolerances are indicated on draings y symols; tolerances and datums 0 allcontained in compartments of a rectangular frame as shon in the diagramelo in the ne-t section.


2W24W*

2 X W

X W12

2 0 W1

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4.4.3INDICATORS OF GEO'ETRIC TOLERANCE

The diagram elo illustrates the symol for straightness in the left hand o-.The other o- gi)es the ma-imum permissile )ariation. The diagram elo also

illustrates the symol for s7uareness; the tolerance and the datum to hich trueposition relates.

4.5 PROECTIONS

4.5.1ORTHOGRAPHIC PROECTION

• F*/st An0,e P/oet*on. The +irst &ngle Pro<ection is a true engineering

draing in that the item in the draing may e shon in se)eral different)ies; each )ie augmenting the information contained in the other.6ormally; three )ies are considered to e sufficient; ut comple- items mayre7uire additional )ies to clarify the situation; hile simple items may eshon in to )ies or one in some cases. It is a characteristic of the +irst &ngle Pro<ection that each )ie shos hat ould e seen y loo$ing on thefar side of an ad<acent )ie.

In the first angle pro<ection; the o<ect alays comes eteen the eye of theoser)er and the pro<ection plane or )ie; as shon in the diagram elo.


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The symol used on draings to indicate first angle pro<ection is deri)ed from

)ies of a circular taper as shon the diagram elo. The symol shos a from)ie and left )ie of the circular taper in first0angle pro<ection.

• T:*/ An0,e P/oet*on. In this pro<ection the layout of the draing is usuallyrather different from that of the +irst &ngle Pro<ection.

It is a characteristic of the Third &ngle Pro<ection that each )ie shos hatould e seen y loo$ing on the near side of an ad<acent )ie.

The +irst &ngle Pro<ection is the traditional method of representation in thiscountry; ut it is eing replaced gradually y the Third &ngle Pro<ection; thislatter system eing preferred y draughtsmen. "oth pro<ections arecommonly encountered and the draing must clearly indicate hichpro<ection is used.

In a Third &ngle Pro<ection an o<ect is positioned in the space of the thirdangle 7uadrant; eteen to principle planes. The planes are imagined to etransparent and the pro<ected )ies of the o<ect are )ieed through theplanes as shon in the diagram elo. The symol used to indicate thirdangle pro<ection on draings is deri)ed as for the first angle pro<ection ut the)ies are positioned differently as shon in the diagram elo.


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• A*,*+/- (*e=s. These )ies ha)e a similar purpose to sectioning in thatthey clarify the information gi)en in the main draing. They are usually )iesta$en at right angles onto a surface hich is inclined in the main draing andsho the true shape of the surface.

4.5.2PICTORIAL PROECTIONS

• Iso6et/* P/oet*on. & simple item such as a plain shear pin could 7uiteeasily e dran on a single sheet of draing paper; as ith the rac$et in thediagram elo. In this case the rac$et is dran in pictorial fashion in amethod called Isometric Pro<ection.

This method is 7uite acceptale for simple parts and is often used to gi)e anengineer an idea of hat an item loo$s li$e. 5i$e other similar pro<ections; thispro<ection is not normally suitale for production purposes. It uses as itsasis; a flat surface represented in the diagram ao)e y the outline &"C;hich is tilted so that its sides & and C form an angle of 3N ith thehori=ontal. The item to e dran is shon placed on the flat surface and isreproduced ithout perspecti)e.

:imensions are difficult to sho on an Isometric Pro<ection unless the item isan e-tremely simple one; and this is one of the reasons for the limited

suitaility of the pro<ection for production purposes.


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• O,*Be D/+=*n0s. li7ue pro<ection is proaly the simplest method ofproducing a pictorial draing since surfaces directly in front of the oser)erill e similar in appearance to the front )ie in an orthographic presentation.The pro<ection hich gi)es depth to the draing are parallel to each otherand may e at any angle; ut the angle of 4N is generally used. There areto specific forms of oli7ue draing; Ca)alier and Cainet pro<ection. Notethat in oth circles on the receding surfaces appear as ellipses; therefore it isad)isale >here possile? to orient an o<ect so that circular features appearin the frontal plane.

• C++,*e/ P/oet*on. In a Ca)alier pro<ection the front and rearpro<ections are shon in true si=e; the disad)antage ith this method isthat the rear pro<ections gi)e the impression of distortion.

• C+*net P/oet*on. So named ecause it as used y cainetma$ers to dra furniture here the front face is generally moreimportant than the sides. In a Cainet pro<ection the frontal plane isshon in true si=e and the receding faces at half scale; this tends to emore popular of the oli7ue draings.

4." TITLE #LOCK INFOR'ATION

4.".1#ORDERS FRA'ES

It is recommended that all sheets should include a frame to enclose the draingarea together ith the title loc$ and other standard information. The frame

should e symmetrical ith the edges of the sheet. & minimum idth of for &3sheet and for &4 sheet; should e left for the order. 5ines forming the framesshould e continuous and a minimum thic$ness of .mm.

4.".2A'END'ENT TO DRAWINGS

&n alteration of a draing may e necessary due to any one of a numer ofreasons; e.g. a change in specification of material; a )ariation in a dimension etc./hate)er the reason; alterations to a draing must e authorised y a 7ualifiedperson in an appro)ed design organisation only; and no attempt must e made to)ary the re7uirements of a draing ithout first otaining the necessary authority.


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nce the alteration to a draing has een appro)ed; it is carried out and thenrecorded y the draing office in a list on the draing itself. The nature of thealteration is shon together ith the date. ,ach alteration is numered orlettered consecuti)ely; the numer or letter eing $non as the Issue 6umer ofthe draing. It is most important to ensure that the draing in use ears thecorrect issue numer and date. In this respect it should e noted that amodification or repair may call for or$ to e carried out to a draing ith anissue numer prior to the latest one. Generally spea$ing hoe)er; the draing inuse should normally e to the latest issue numer. If you are not sure if the

draing is the correct issue and date; you should refer to the design authoritythat issued the draing. & typical alteration is shon in the diagram elo. If adraing amendment affects interchangeaility of the item; the part numer ischanged.

4.! 'ICRO>FIL' 'ICRO>FICHE

8icro0fiche draings are miniature draings on film. This system has een usede-tensi)ely throughout the 1*'Ds and 1**Ds and is still one of the main methodsof )ieing 8aintenance 8anuals and Illustrated Parts Catalogues >IPCDs?. Inorder to produce the films; each page of the manual is photographed; reduced insi=e and placed on a reel of film or an & sheet film. The miniature film is )ieedith an optical )ieer >reader? and most can reproduce a copy of the re7uiredpages on &4 sheet. The complete maintenance manual for a modern largeaircraft can e produced on to or three micro0fiche cassettes. /hen anamendment is necessary; a ne set of cassettes are sent y the manufacturer.These readers; particularly the cassette )ersions are )ery e-pensi)e and oftenun0reliale especially hen old.

4.$ CO'PUTERISED PRESENTATIONS

Since the mid 1**Fs many aircraft ha)e manuals and I.P.C.Fs ha)e eendigitised and reproduced on C: Roms. They can e )ieed and printed using astandard Personal Computer >P.C?. They are significantly etter than micro0filmsecause they are easier to copy and more reliale. They are also easier toamend. The technology is a)ailale for the :esign &uthority or 8anufacturer tolin$ directly to the perator or maintenance ase )ia the internet.


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4.& ATA 1)) SPECIFICATION

In order to ma$e it easier for engineers to use maintenance pulications; astandard identification system has een de)eloped. "efore this system e-isted;each aircraft manufacturer used a different system of manuals. The &T& 1system as de)eloped y the &ir Transport &ssociation of &merica and mostmodern manuals ill conform to this specification.

The &ir Transport &ssociation of &merica >&.T.&.? issued the specifications for8anufacturers Technical :ata Aune 1; 1*!.

MThis specification estalishes a standard for the presentation of technical data;y an aircraft accessory; or component manufacturer re7uired for their respecti)eproductsM.

MIn order to standardise the treatment of su<ect matter and to simplify the userFsprolem in locating instructions; a uniform method of arranging material in allpulications has een de)elopedM.

ne of the main aims of the specification is to ensure that all the informationneeded y an operator is included in one or other of the manuals pro)ided y theaircraft manufacturer; e-cept accessory o)erhaul data hich is co)ered in )endoro)erhaul manuals. This is in contrast ith some other specifications; hich

re7uire not only the use of manuals supplied y the aircraft manufacturers ut thee-tensi)e use of )endor manuals for descripti)e; ser)icing and maintenance dataon accessory e7uipment.

&T& specification 1 calls for the folloing manuals

8aintenance 8anual

/iring :iagram 8anual

Illustrated Parts Catalogue

)erhaul 8anual

Structural Repair 8anual

Tool and ,7uipment 5ists

/eight and "alance 8anual

A*t*on+, '+n+,s =:*: 6+- e 7,*s:eJ

Cre 8anual

8aintenance Schedule 0 generally included in the 8aintenance8anual.

The Specification calls for one other medium for information Ser)ice

"ulletins. These "ulletins pro)ide to 7uite different types ofinformation. Some "ulletins pro)ide a 7uic$ path for any urgent YonceonlyF inspection that may ha)e een highlighted y a fault disco)eredon another aircraft of the same typeK others pro)ide 7uic$ informationon modifications; e-plaining their purpose and gi)ing the method ofincorporation.

&ccording to the specification; the manufacturerFs recommended timelimits for inspections; tests; and o)erhaul should e pro)ided in aseparate manual called the ?'+*nten+ne S:e,e?.


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The &T& 1 Specification Yrea$sF an aircraft don into its ma<orsystems; such as air conditioning; electrical poer; and landing gearetc. and then allocates these systems chapter numers. Thus; &irconditioning is Chapter 21K ,lectrical Poer; Chapter 24; the 5andingGear; Chapter 32. The )arious systems chapters are arrangedalphaetically; there eing no natural order or precedence orimportance. A @e+t/e o@ t:e S7e*@*+t*on *s t:+t =:e/e+77,*+,e t:e +/*os C:+7te/ N6e/s +/e t:e s+6e *n +,, t:e6+n+,s.

+or e-ample information on L+n*n0 0e+/ is found in C:+7te/ 32 inthe 8aintenance 8anual; /iring :iagram 8anual; )erhaul 8anualand in the Illustrated Parts Catalogue. Should it e necessary to issuea Ser)ice "ulletin referring to the landing gear; the ulletin ould carrythe prefi- Y32F. +uselage structure data; co)ered in Chapter 3; isfound under Chapter 3 in the 8aintenance 8anual; Illustrated PartsCatalogue and in the Structural Repair 8anual.

8ost systems are too comple- to e co)ered in one go; and Somesu0systems may e sufficiently comple- to re7uire furthersu0di)ision. Thus; Y8ain gearF could e ro$en don into Y8ain legF;YSide stay assemlyF and Y+airingsF; these eing allocated reference

numers such as 3201011; 3201021 and 3201031 respecti)ely.


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ATA. S7e. 1)) > S-ste6s

S-s. S T*t,e

21 A*/ Con*t*on*n0

General1 Compression2 :istriution3 Pressurisation Control4 9eating Cooling

! Temperature Control% 8oisture @ &ir Contaminate

Control

22 Ato F,*0:t

General1 &utopilot2 Speed0&ttitude Correction

3 &uto Throttle4 System 8onitor

23 Co66n*+t*ons

General1 9igh +re7uency >9+?2 (9+@#9+3 Passenger &ddress

,ntertainment4 Interphone &udio Integrating! Static :ischarge

% &udio (ideo 8onitoring24 E,et/*+, Po=e/

General1 Generator :ri)e2 &C Generation3 :C Generation4 ,-ternal Poer ,lectrical 5oad :istriution

S-s. S T*t,e

25 EB*76ent F/n*s:*n0s

General1 +light Compartment

2 Passenger Compartment3 "uffet @ Galley4 5a)atories Cargo Compartments @ &G

Spray &pparatus! ,mergency% &ccessory Compartments

2" F*/e P/otet*on

General1 :etection2 ,-tinguishing

3 ,-plosion Suppression

2! F,*0:t Cont/o,s

General1 &ileron and Ta2 Rudder @ Rudder)ator Ta3 ,le)ator Ta4 9ori=ontal Stailisers @

Stailator+laps! Spoiler; :rag :e)ices

(ariale &erodynamic

+airings% Gust 5oc$ :ampener ' 5ift &ugmenting

2$ Fe,

General1 Storage2 :istriution @ :rain (al)es3:ump4 Indicating

2& H-/+,* Po=e/

General18ain2 &u-iliary3 Indicating


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S-s. S T*t,e

3) Ie R+*n P/otet*on

General1 &irfoil2 &ir Inta$e3 Pilot Static4 /indos /indshields &ntennas Radomes

! Propellers @ Rotors% /ater 5ines' :etection

31 In*+t*n0 Reo/*n0S-ste6s

General1 #nassigned2 #nassigned3 Recorders4 Central Computers Central /arning System

32 L+n*n0 Ge+/

General1 8ain gear 2 6ose Gear @ Tail Gear 3 ,-tension Retraction; 5e)el

Sitch4 /heels "ra$es Steering! Position; /arning Ground

Safety Sitch% Supplementary Gear @ S$is @

+loats

33 L*0:ts

General1 +light Compartment

&nnunciator Panels2 Passenger Compartments3 Cargo Ser)ice

Compartments4 ,-terior 5ighting ,mergency 5ighting

34 N+*0+t*on

General1 +light ,n)ironment :ata2 &ttitude :irection3 5anding Ta-ing &ids4 Independent Position

:etermining :ependent Position

:etermining! Position Computing

S-s. S T*t,e

35 O-0en

General1Cre2 Passenger 3 Portale

3" Pne6+t*

General1 :istriution2 Indicating

3! (+6 P/ess/e

General1 :istriution2 Indicating

3$ W+te/ W+ste

General1 Portale

2/ash3 /aste :isposal4 &ir Supply

3& E,et/*+, E,et/on* P+ne,s ',t*7/7ose Co67onents

General1 Instrument Control Panels2 ,lectrical ,lectronic

,7uipment Rac$s3 ,lectrical ,lectronic Aunction

"o-es

4 8ultipurpose ,lectronicComponents

Integrated Circuits! Printed Circuit Card

&ssemlies

4& A*/o/ne A*,*+/- Po=e/

General1 Poer Plant2 ,ngine3 ,ngine +uel Control4 Ignition @ Starting&ir ! ,ngine Controls% Indicating' ,-haust*1

51 St/t/es

General


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S-s. S T*t,e

52 Doo/s

General1 Passenger @ Cre2 ,mergency ,-it3Cargo4 Ser)ice +i-ed Interior

! ,ntrance Stairs% :oor /arning' 5anding Gear

53 Fse,+0e

General1 8ain frame2 &u-iliary Structure3 Pates @ S$in4 &ttach +ittings &erodynamic +airings

54 N+e,,es P-,ons General1 8ain +rame2 &u-iliary Structure3 Pates @ S$in4 &ttach +ittings +illets @ +airings

55 St+*,*se/s

General1 9ori=ontal Stailisers @

Stailator 2 ,le)ator @ ,le)on3 (ertical Stailiser 4 Rudder @ Rudder)ator &ttach +ittings

5" W*no=s

General1 +light Compartment2Cain3:oor 4 Inspection ser)ation

5! W*n0s

General1 8ain +rame2 &u-iliary Structure3 Plates @ S$in4 &ttach +ittings +light Surfaces

S-s. S T*t,e

"1 P/o7e,,e/s

General1 Propeller &ssemly2 Controlling3 "ra$ing4 Indicating

"5 Roto/s

General1 8ain Rotor 2 &nti0tor7ue Rotor &ssemly3 &ccessory :ri)ing4 Controlling "ra$ing! Indicating

!1 Po=e/7,+nt

General1 Coling

28ounts3 +ire seals Shrouds4 &ttach +ittings ,lectrical 9arness! ,ngine &ir Inta$es% ,ngine :rains

!2 ;T< T/*ne T/o7/o7

General1 Reduction Gear Shaft

section2 &ir Inta$e Section3 Compressor Section4 Comustion Section Turine Section! &ccessory :ri)es% "y0pass Section

!2 ;R< En0*ne Re*7/o+t*n0

General1 +ront section2 Poer Section3 Cylinder Section

4 Supercharger Section 5urication

!3 En0*ne Fe, Cont/o,

General1 :istriution2 Controlling @ Go)erning3 Indicating


Page 110!*



S-s. S T*t,e

!4 I0n*t*on

General1 ,lectrical Poer Supply2 :istriution3 Sitching

!5 #,ee A*/

General1 ,ngine &nti0Icing2 &ccessory Cooling3 Compressor Control4 Indicating

!" En0*ne Cont/o,s

General1 Poer Control2 ,mergency Shutdon

!! En0*ne In*+t*n0

General1Poer 2 Temperature3 &nalyser

!$ En0*ne E:+st

General1 Collector @ 6o==le2 6oise Suppressor 3 Thrust Re)erser 4 Supplementary &ir

S-s. S T*t,e

!& En0*ne O*,

General1 Storage >:ry Sump?2 :istriution3 Indicating

$) St+/t*n0

General1 Cran$ing

$1 T/*nes ;Re*7/o+t*n0 En0.<

General1 Poer Reco)ery2 Turo0Supercharger

$2 W+te/ Inet*on

General1 Storage2 :istriution

3 :umping Pumping4 Indicating

$3 Re6ote Ge+/ #oes ;En0. D/.<

General1 :ri)e Shaft Section2 Gearo- Section


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4.1) AERONAUTICAL STANDARDS

Ci)il aircraft manufactured in the #E are constructed of parts and componentsmanufactured in compliance ith appro)ed draings. To ensure correctness andsuitaility of design; appro)ed draings and associated documents must eproduced y a :esign rganisation appro)ed y the C&& in accordance ithSection &' of "ritish Ci)il &irorthiness Re7uirements >"C&RDs?.

Section &' further descries that all calculations on hich the airorthiness of

the aircraft depends; must e independently chec$ed; thus the design draingitself is su<ect to a system of inspection as are the parts produced to itsre7uirements.

The appro)ed Inspection rganisation or the engineer should ensure that thedraings are appro)ed and that the parts are correct to these draings andassociated documents. &ny de)iation from the draings and their associateddocuments must e co)ered y a suitale concession procedure as gi)en in C&P!2.

8ost appro)ed design organisations no or$ in accordance ith "S3'J1*'4hich standardises the are)iations; symols and con)entions used inengineering draing; and these notes ha)e een ritten in conformity ith thatstandard.

4.11WIRING DIAGRA'S

4.12SCHE'ATIC DIAGRA'S


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Intent*on+,,- #,+n


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5. FITS CLEARANCES

5.1 SIES OF HOLES

It has already een stated in part 2 of these notes that it is impossile tomanufacture aircraft parts to e-act dimensions. In this section e ill loo$ atsi=es of holes re7uired in aircraft parts. &ircraft fasteners such as ri)ets or oltscome in a )ariety of si=es and types. The nominal diameter of a ri)et may e

3.2mm. &n aircraft ing attachment olt may e mm in diameter. The 7uestionis; hat si=e of hole do e need for these fasteners. The o)ious anser is3.2mm for the ri)et and mm for the ing attachment olt. If this ere the casee might find it difficult to fit the ri)et or olt in the hole. There is also thepossiility that the ri)et or olt diameter may not e e-actly 3.2mm or mm. Thesi=e of the hole may also e smaller or larger than specified.

If the ri)et or olt is slightly smaller than the hole the <oint made may e slac$ orloose. If e-actly the same si=e; the <oint ill e more rigid. If e no considere-amples of a shaft in a hole; the same ill apply. /e may also re7uire; ydesign )ariations of looseness or tightness of the shaft in the hole. +or e-ampleJ

• If the shaft must rotate in the hole the shaft must alays e smaller than thehole.

• If the shaft has to dri)e a gear heel and the heel is held onto the shaft yfriction; the shaft must alays e slightly larger than the hole >and the shaftill e hammered into the hole?

5.2 CLASSES OF FIT

In oth of the pre)ious e-amples gi)en e can identify the type or class of fit.

5.2.1CLEARANCE FIT

The first e-ample here the shaft is re7uired torotate in the hole is classed as a Hclearance fit. Itis also sometimes called a Hrunning fit. If e usea nominal si=e of 2mm and ensure that the holeis made eteen 2. and 2.2mm; the shaftmust alays e made slightly smaller; fore-ample eteen 24.*! and 24.*'mm. This illgi)e a minimum Hclearance of .2mm and ama-imum clearance of .!mm.

5.2.2INTERFERENCE FIT

In the second e-ample e ant the shaft to dri)ethe heel and so the shaft must not rotate in theheel. This is called an Hinterference fit orHdri)ing fit. In this case e again use a nominalsi=e of 2mm and ensure that the hole is madeeteen 24.*' and 2.mm; the shaft mustalays e made slightly larger; for e-ampleeteen 2.2 and 2.4mm. This ill mean thatthe shaft ill alays e at least .2mm largerthan the largest hole si=e.


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5.2.3TRANSITION FIT

In many cases it is not importantthat the shaft is a clearance fit oran interference fit. The shaft andhole si=es may )ary so thatsometimes the shaft is slightlysmaller than the hole andsometimes slightly larger. & solid

ri)et may sometimes fit easily intoa hole and sometimes it has to edri)en in. This type of fit is called aHtransition fit. If the shaft si=e iseteen 24.*' and 2.2mm andthe hole si=e is gi)en the sametolerance; sometimes the shaft is

the iggest and sometimes the hole.

5.3 CO''ON SYSTE'S OF FITS CLEARANCES

/hen e ha)e designed a system so that one component chosen at random ill

assemle correctly ith any mating component and gi)e the re7uired clearanceas necessary e call it an interchangeale system; limit system or system oflimits and fits.

&s already mentioned it is necessary to classify the )arious types of fit. /e ha)ealready identified clearance; transition and interference. ther commonclassifications are as follosJ

a? Running +it 0 a smooth easy fit for the purpose of a mo)ing earing

? Push +it Can e assemled ith light hand pressure >locating pins anddoels?

c? :ri)ing or Press +it Can e assemled ith a hammer or ith medium

pressure. Gi)es a semi0permanent fit such as necessary for a $eyed pulleyon a shaft.

d? +orce +it Re7uired great pressure to assemle and gi)es a permanent fit.#sed for heels and hus on shafts from hich they are ne)er li$ely to eremo)ed.

These may e further sudi)ided y adding fits such as Hslac$ running andHclose running or Hlight dri)ing and Hhea)y dri)ing.

5.3.1SHAFT AND HOLE #ASIS

The )ariation in shaft and hole si=e that gi)es the re7uired fit is called thealloance and this may e otained y eitherJ

a? Eeeping the hole constant and )arying the shaft diameter to gi)e theappropriate fit or

? Eeeping the shaft constant and )arying the hole diameter

Eeeping the hole constant is called the hole asis and $eeping the shaft constantis called the shaft asis.

&ll modern limit systems fa)our the hole asis ecause most holes are producedith a fi-ed si=e drill or reamer; hile shafts are turned using an easily ad<ustaletool such as a lathe. It is therefore easier to ad<ust the shaft to the hole ratherthan the hole to the shaft.


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5.3.2UNILATERAL AND #I>LATERAL

The difference eteen high and lo limits gi)en in dimensions is called theHtolerance. Sometimes the tolerance is only alloed on one side of the nominaldiameter e.g. 2. X .2 0 .. This is called a Hunilateral tolerance. If thetolerance is alloed on oth sides of the nominal e.g. 2. X@0 .2 the toleranceis called Hilateral.

5.3.3LI'IT SYSTE'

&n effecti)e limit system must allo for different classes of fit; different nominalsi=es of hole and shaft and also different 7ualities of product. If the limits are tooclose; a etter control of fit is possile; ut the cost ill increase. /ider limits illcheapen the cost; ut not gi)e a satisfactory fit.

The limit system commonly used in the #E is set out in "ritish Standard >"S?4. This as introduced in 1*!* and allos for 2% types of fit and 1' grades oftolerance. In the system the 2% possile holes are designated y capital letters &"C:, ect; and the shafts y small letters acde ect. The 1' accuracygrades are co)ered y numerals ; 1; 2; 3; ect. To specify any particular hole orshaft the rule is to rite the letter folloed y the numeral e.g. 9% for a hole andf% for a hole. & fit in)ol)ing these to elements ould e ritten 9% f% or 9%@f%.

& copy of the "S 4& data sheet shos a selection of the IS 9ole ased fitso)er a range of hole si=es from 2 mm.

The general trend for the shafts is that the range a to g ha)e oth limits less thanthe nominal si=e and tend to gi)e clearance fits. The h shafts ha)e their nominalsi=e as their upper limit and tend to gi)e a close running fit hen associated ith9 holes. The < shafts ha)e their limits disposed ao)e and elo the nominal andtend to gi)e a fit eteen a clearance and interference >transition fit?. The $ to =range lie ao)e the nominal and gi)e )arying forms of interference fit.


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". AIRCRAFT WEIGHT #ALANCE

".1 PURPOSE

The main purposes of aircraft eight and alance are to maintain safety and toachie)e efficiency in flight. The position of loads such as passengers; fuel; cargoand e7uipment ill alter the position of the Centre of Gra)ity >C of G? of theaircraft. Incorrect loading ill affect the aircraft rate of clim; manoeu)raility;

ceiling; speed and fuel consumption. If the C of G is too far forard; it ouldresult in a nose hea)y condition hich could e potentially dangerous on ta$e0offand landing. If the C of G is too far aft; the tail0hea)y condition ill increase thetendency of the aircraft to stall and ma$e landing more difficult. Staility of theaircraft ill also e affected ith the C of G outside the normal operational limits.Pro)ided the C of G lies ithin specified limits; the aircraft should e safe to fly.

".2 AR OPS RE%UIRE'ENTS

&n aircraft operator shall ensure that the loading; mass and centre of gra)ity ofthe aeroplane complies ith the limitations specified in the +light 8anual orperations 8anual if more restricti)e.

&n operator must estalish the mass and the centre of gra)ity of any aeroplaney actual eighing prior to initial entry into ser)ice and thereafter at inter)als of 4years if indi)idual aeroplane masses are used and * years if fleet masses areused. The accumulated effects of modifications and repairs on the mass andalance must e accounted for and properly documented. +urthermore;aeroplanes must e re0eighed if the effect of modifications on the mass andalance is not accurately $non.

".3 PRINCIPLES OF WEIGHT AND #ALANCE

Principle of 8oments 0 & moment is the product of a force and the distance

>moment arm? at hich the force acts. In aircraft eight and alance terms eare concerned ith the force produced y the masses on the aircraft acting at adistance from a specific datum point on the aircraft. The sum of all momentsaout any point can e shon to e e7ual to the moment of the resultant forceaout that datum point. &s the entire eight of the aircraft may e considered toe concentrated at the C of G; the total moment of the aircraft aout the datum isthe aircraft eight times the hori=ontal distance eteen the C of G and thedatum.



".4 DEFINITIONS

The folloing definitions are in common useJ

• D+t6 0 The datum is an imaginary )ertical plane from hich hori=ontalmeasurements are ta$en. The locations of aggage compartments; fueltan$s; seats; engines; propellers; etc. are all listed in the aircraft

specifications. There is no fi-ed rule for the location of the datum. Themanufacturer ill normally specify the nose of the aircraft; ut it could e atthe front main ul$head or e)en forard of the aircraft nose.

• A/6 0 This is the hori=ontal distance from an item or piece of e7uipment tothe datum. The armFs distance is usually measured in inches and may epreceded y a X >plus? or 0 >minus? sign. The plus sign indicates that thedistance is aft of the datum and the minus sign indicates distances forard ofthe datum.

• 'o6ent 0 This should ha)e een co)ered in 8odule 2 >Science?. To recap;a moment is the product of a force multiplied y the distance aout hich theforce acts. In the case of eight and alance; the force is the eight >in

pounds? and the distance is the arm >in inches?. & eight of 4 ls 12inches aft of the datum ill ha)e a moment of 4 - 12 O 4;' ls.inches.

NoteJIt is important to consider hether a )alue is X)e or 0)e hen moments arecalculated and the folloing con)entions are usedJ

• :istances hori=ontal >X? aft of the datum; >0? forard of the datum

• /eight added >X?; eight remo)ed >0?

• Centre of Gra)ity >C of G? This is the point aout hich all of theeight of the aircraft or o<ect is concentrated. &n aircraft could esuspended from this point and it ould not adopt a nose don or tail

don attitude.• #+s* EB*76ent 0 This term is used to include the un0consumale fluids

>e.g. coolant and hydraulic fluid?; and e7uipment that is common to all rolesfor hich the operator intends to use the aircraft.

• D/- O7e/+t*n0 '+ss 0 This is the total mass of the aeroplane ready for aspecific type of operation e-cluding all usale fuel and traffic load. This massincludes cre and cre aggage; catering and remo)ale passenger ser)icee7uipment and potale ater and la)atory chemicals. NoteJ This is a neterm as specified in A&R PS. The terms F"asic /eightF and Z(ariale/eightD has pre)iously een used; and oth of these comined ould e thesame as Z:ry perating 8assD.

• T/+@@* Lo+ 0 This includes the total mass of passengers; aggage andcargo; including any non0re)enue load.

• '+*66 St/t/+, T+e O@@ '+ss 0 The ma-imum permissile totalaeroplane mass at the start of the ta$e0off run.

• '+*66 St/t/+, L+n*n0 '+ss 0 The ma-imum permissile totalaeroplane mass upon landing under normal circumstances.

• Cent/e o@ G/+*t- #+,+ne L*6*ts. 0 +or normal operation of the aircraft theCentre of Gra)ity should e eteen the +orard and &ft limits as specifiedy the manufacturer. If the C of G is outside these limits; the aircraftperformance ill e affected and the aircraft may e unsafe.



".5 WEIGHT AND CENTRE OF GRA(ITY SCHEDULE

This document is used e-tensi)ely in the #E and details the "asic /eight and Cof G position of the aircraft; and the eight and le)er arms of the )arious items ofload; including fuel; oil and other fluids. The schedule is normally di)ided intoPart & 0 "asic /eight; Part " 0 (ariale 5oad and Part C 0 5oading Information>:isposale 5oad?. The folloing is an e-tract from "C&RFs relating to eightschedules.

• & /eight and Centre of Gra)ity Schedule shall e pro)ided for each aircrafthere the 8T/& 8a-imum Total /eight &uthorised? e-ceeds 2%3 $g.

• +or aircraft not e-ceeding 2%3 $g 8T/&; either a /eight and Centre ofGra)ity Schedule shall e pro)ided or alternati)ely a 5oad and :istriutionSchedule hich complies ith "C&R Section &; Chapter &01; para !.1.

• +or ne aircraft hich e-ceed 2%3 $g; ut do not e-ceed % $g; theinformation contained in Parts " and C of the Schedule may e gi)en as partof the /eight and "alance Report.

• & /eight and Centre of Gra)ity Schedule must pro)ide the folloing. ,achSchedule must e identified y the aircraft registration mar$s or theconstructors serial numer. The date of issue must e on the Schedule and

signed y an authorised representati)e of the C&&; and if applicale astatement shall e included indicating that the Schedule supersedes allearlier issues. It is also necessary to refer to the date or reference numer>or oth? of the /eight and "alance Report; or other acceptale informationon hich the Schedule is ased.

perators must also re)ise the /eight and Centre of Gra)ity Schedule hen it is$non that the eight and C of G has changed in e-cess of a ma-imum figureagreed y the C&&. If the aircraft has not een re0eighed; the re)ised /eightand Centre of Gra)ity Schedule must state that it has een calculated on theasis of the last /eight and "alance Report and the $non eight and C of Gchanges. & record of the calculations should e retained for future reference.

& copy of the Schedule is retained y the operator and a further copy sent to theC&& &irorthiness :i)ision hich shall include any related list of "asic,7uipment. +or aircraft of 8T/& not e-ceeding % Eg; a copy of the /eightand C of G Schedule must e included in the +light 8anual. If a +light 8anual isnot a re7uirement; the Schedule must e displayed or retained in a stoage inthe aircraft. & similar arrangement is often used in larger aircraft.

&ircraft must e eighed to determine the "asic /eight and the C of G positionhen all the manufacturing processes ha)e een completed. &ircraft; ith8T/& e-ceeding % $g >12 l? must e re0eighed ithin to years of thedate of manufacture; after this; a chec$ eighing must e carried out at inter)alsnot e-ceeding years and at times laid don y the C&&. &ircraft elo 8T/&

% $g must e re0eighed as re7uired y the C&&.

In ma$ing decisions on eighing; the C&& considers the history of the aircraft; itFsflying performance; and the proale effect on the eight after a ma<or o)erhaul;or ma<or modification; repair or replacement.

Certain types of aircraft may e eighed on a sampling asis >i.e. arepresentati)e aircraft; as eighed ould e acceptale for others of the samestandard? y agreement ith the C&&.

&n alternati)e to the periodic chec$ eighing is for the operator to estalish afleet mean eight >i.e. "asic /eight? and fleet mean Centre of Gra)ity position.The initial fleet mean eight is ased on the mean eights of all the aircraft of

the same type in the fleet. The figure may e re)ised annually y sampleeighing.



/hen an aircraft is eighed; the e7uipment and other items of load; such as fluidin the tan$s must e recorded. This recorded load should not differ significantlyfrom the "asic ,7uipment 5ist associated ith the /eight and Centre of Gra)itySchedule. In circumstances here there is a significant difference eteen the"asic /eight of the aircraft and the operating eight >i.e. "asic /eight plus the(ariale 5oad? not accountale to structural changes rought aout ymodifications@repairs; the C&& may re7uire the actual eights of the (ariale5oad items e ascertained.

&ll records of eighing; including calculations in)ol)ed; must e a)ailale to theC&&. Records are retained y the aircraft manufacturer; o)erhauler or operator;and hen the aircraft is eighed again; the pre)ious records must not edestroyed; ut retained ith the aircraft records.

perators must retain all $non eight and C.G. changes that occur after theaircraft has een eighed.

"efore issue of a Certificate of &irorthiness for a prototype; prototype >modified?or series aircraft; 8/T& e-ceeding % $g; a /eight and "alance Report muste prepared y a C&& &ppro)ed rganisation. This Report is intended to recordthe essential data to enale a particular aircraft to e correctly loaded; and toinclude sufficient information for the operator to produce loading instructions in

accordance ith the pro)isions of the &.6.. The report applies to the aircraft inthe condition in hich it is deli)ered from the constructor to the operator. The/eight and "alance Report must include the folloing itemsJ

• Reference numer and :ate.

• :esignation; constructors numer; nationality and registration mar$s of theaircraft.

• & copy of the /eighing Record.

• & copy of the /eight and Centre of Gra)ity Schedule; including the "asic,7uipment 5ist of this is separate from Part & of the Schedule.

• & diagram and a description of the datum points used for eighing andloading; and an e-planation of the relationship of these points to fuselageframe numering systems and; here applicale; to the Standard 8eanChord >S8C? or 8ean &erodynamic Chord >8&C?.

• Information on the le)er arms appropriate to items of :isposale 5oad. Thisill include the le)er arms for fuel; oil and other consumale fluids orsustances in )arious tan$s >including agricultural materials?K also le)er armsof passengers in seats appropriate to the )arious seating layouts and meanle)er arms of the )arious aggage holds or compartments. These le)er armsmay e shon y means of diagrams or graphs as appropriate.

• :etails of any significant effect on the a@c C of G of any change in

configuration; such as retraction of the landing gear.

"." PRINCIPLES OF AIRCRAFT WEIGHT AND #ALANCE

The position of the C of G of any system may e found using the folloingprocessJ

1. Calculate the moment of each load; i.e. y multiplying the eight y the arm>distance from the reference datum?.

2. Calculate the total eight y adding the eight of each load >plus the eightof the eam?.

3. &dd &55 of the moments. >Total moment?.

4. :i)ide the Total moment y the Total eight.



In the e-ample shon; the reference datum is at the left of the eam. & mass of2 ls. is 1M from the datum and another mass of 4 ls. is 'M from thedatum. The mass of the eam is ls and the length of the eam is 1M. Tofind the position of the Centre of Gra)ity.

Ite6 '+ss ;Ls< A/6 ;In:es< 'o6ent ;'+ss 9 A/6<

8ass 1 2 1 2;

8ass 2 4 ' 32;

"eam 2;

Total 1;1 *; ls. inches

Centre of Gra)ity position O Total 8oment@Total 8ass O *;@1;1 O 3.!4

So the position of the centre of Gra)ity is 3.!4 inches to the right of the datum.

Calculation of &ircraft /eight and Centre of Gra)ity

The eight and C.G. position of an aircraft is calculated in much the same ayas the pre)ious e-ample. The "asic /eight or F:ry perating 8assF of theaircraft corresponds to the eight of the eam; and is usually found out yeighing the aircraft. The )ariale and disposale loads or FTraffic 5oadsF; suchas fuel; cre; passengers and cargo correspond to the eam loads. "efore eachflight; the eight and moment of these items should e determined so that theaircraft eight and position of the C.G. can e determined prior to flight to see ifthey are ithin the appro)ed limits. The operational limits for the fore and aftpositions of the C.G. are defined in the aircraft flight manual or other documentassociated ith the Certificate of &irorthiness; such as the ners 8anual.

/eighing ,7uipment may consist of eighridge scales; hydrostatic eighing

units or electrical@electronic eighing e7uipment ased on the strain gaugeprinciple. The capacity of the e7uipment must e compatile ith the load sothat accurate measurements may e otained. &ll eighing e7uipment shoulde chec$ed; ad<usted and certified y a competent authority at periods note-ceeding one year and the =ero indication chec$ed efore any eighingcommences. The eighing e7uipment may consist of one of the folloingJ

• We*0:/*0e S+,es 0 This consists of a separate eighing platform foreach heel or ogey; the eight at each reaction point eing indicateddirectly on the alance arm or on a dial indicator. 5arge aircraft may eeighed in a hangar using portale eighridge scales or on a eighridgeset permanently into the floor.



• H-/ost+t* We*0:*n0 Un*ts 0 The operation of these units is ased on theprinciple that fluid pressure in a cylinder in hich a piston is or$ing dependson the area of the piston and the load applied to it. The units are placedeteen the lifting <ac$s and the aircraft <ac$ing points and the eight at eachposition recorded on a gauge. The gauge may e calirated directly intoeight units or a con)ersion may e re7uired to otain the correct units. It isimportant that the <ac$s used ith these units are )ertical and the unitscorrectly positioned; otherise side loads may e imposed on the units andinaccurate readings otained.

• E,et/*+, o/ E,et/on* We*0:*n0 EB*76ent 0 ,7uipment of this typeincorporates three or more eighing cells using metallic resistance elementsor strain gauges; hose resistance )aries ith change in length due to elasticstrain. These strain gauges are either incorporated into cells eteen theaircraft and the <ac$s; or they are used in portale eighridge platformsplaced eneath the aircraft heels. The output may e measured ith agal)anometer; or sent to an instrumentation unit hich adds all of theplatform )alues and digitally displays the aircraft load.

".! PREPARATION FOR WEIGHING

• The aircraft should e in the condition descried in the /eight and Centre ofGra)ity Schedule ith fuel and engine oil partially or completely drained inaccordance ith the manufacturers re7uirements and e7uipment positionedas re7uired.

• /eighing should e carried out in a closed hangar; and it is recommendedthat the aircraft e positioned se)eral hours efore eighing so that an e)entemperature can e assumed and the aircraft is free from moisture. Ifeighing in the open is una)oidale; it should e carried out on firm; le)elground ith minimal ind; hen the aircraft is not affected y frost or de.Se)eral readings should e ta$en at each reaction point to otain a relialea)erage reading.

• The aircraft should e placed into FRigging PositionF so that consistent resultsare otained.

• Some light aircraft ith tail heels; ha)e a negati)e load on the tail hen inrigging position as a result of the C.G. eing forard of the main heelcentres. In such cases; it may e possile to use a <ac$ at the nose. If not; aspring alance may e anchored to the ground and attached to the tail heel.The reaction thus otained ill e a negati)e reaction and its )alue deductedfrom the aircraft eight and treated as a minus 7uantity hen calculatingC.G. position. The eight of the rope and spring alance must also e addedto the spring alance reading.

".$ WEIGHING ON AIRCRAFT ACKS

• Aac$ing should e carried out i.a.. the 8aintenance 8anual proceduresand suitale <ac$ing adaptors fitted at the <ac$ing points.

• /eighing units of sufficient capacity should e fitted to the <ac$s and the <ac$s positioned at each <ac$ing point.

• [ero indication of each eighing unit should e )erified.

• The aircraft should e raised e)enly until the aircraft is clear of the groundand then the aircraft should e le)elled.

• Readings should e made at each eighing point and to ensure

representati)e readings are otained; a second reading otained.



• /hen electrical eighing cells are eing used; they should e sitched on3 minutes efore eighing to enale the circuits to stailise.

If the aircraft configuration is as shon in the C.G. is o)iously forard of themain undercarriage; e can use the position of the main undercarriage as areference datum and the C.G. can e found y using the folloing formulaJ

/here & O distance eteen front and rear reactions

" O /eight at nose heel

C O "asic eight >sum of reactions?

Thus O O O %.'2 in

So the C.G. is %.'2 in forard of the main heel centre0line.

It is not alays ad)isale to use the main heel a-is as a reference datum. I nthe folloing e-ample; the pre)ious aircraft details are shon; ut ith aReference datum eteen the nose heel and the main heels.

Relati)e to Reference :atum

In this case e use the formula C.G. O Total 8oment >T8? Total /eight >T/?Total /eight >T/?

Rememer AFT o@ Re@e/ene e Fo/=+/ o@ Re@e/ene >e



We*0:t ;,< A/6 ;*n< 'o6ent ;* *n<

5eft main heel 1** × >X? 1 O >X? 1**

Right main heel 2 × >X? 1 O >X? 2

6ose heel 22 × >0? O >0? 11

Tot+,s 422) ;< 3$& )))

T8 O 3'* l inT/ O 422 l

O *2.1' in

So C.G. O >X? *2.1' in i.e. *2.1' &+T of Reference :atum.

".& STANDARD 'EAN CHORD ;S.'.C.<

Since the position of the C.G. is an aerodynamic consideration; itFs position issometimes specified as a percentage of the S.8.C. of the ing; measured &+Tfrom the leading edge. The percentage S.8.C. may e calculated as follosJ- 1

/here & O distance of the C.G. from the Ref. datum

" O distance of the S.8.C. leading edge from Ref. datum

C O length of the S.8.C.

× 1 O × 1 O × 1 O 1!.! \

Percentage >S.8.C.?

".1)CHANGES IN #ASIC WEIGHT

/hen an item of +s* eB*76ent is added; remo)ed or re0positioned in anaircraft; calculations must e made to determine the effect on oth +s* =e*0:tand C.G. In the case of modifications; here the total eight and moment foradditional parts is not 7uoted in the appropriate modification leaflet; the additionalparts must e accurately eighed and their moments calculated relati)e to thereference datum. In order to find the ne "asic /eight and moment of theaircraft; the eight and moment of the e7uipment added or remo)ed must econsidered as follosJ



• /hen e7uipment has een added; the eight must e added to the original"asic /eightK if the arm of the ne e7uipment is X)e i.e. aft of the C.G.Reference datum; then the moment must e added to the original moment. Ifthe arm is 0)e i.e. forard of the C.G. :atum; then the moment must esutracted.

• /hen e7uipment has een remo)ed; the eight must e deducted from theoriginal eight. If the arm is positi)e the moment must e deducted from theoriginal moment and )ice )ersa.

• The ne C.G. position is calculated y di)iding the ne total moment y thene "asic /eight.

".11 E9A'PLES OF ALTERATIONS TO #ASIC WEIGHT

The folloing e-amples are for an aeroplane hoseJ

• "asic /eight is 14;' l.

• C.G. Reference :atum is at +uselage Station 1 i.e. 1M aft of fuselagestation =ero.

• C.G is at station 12 i.e. X 2M aft of the Reference :atum.

E+67,e 1J & Radar System is installed in the aircraft comprisingJ

• & radar transmitter eight 2' l at fuselage station 13

• & radar controller eight 4 l at fuselage station 4

• & scanner eight 24 l at fuselage station 1

We*0:t ;,< A/6 ;*n< 'o6ent ;* *n<

riginal &ircraft 14;' X 2 X 3%

Transmitter 2' X 3 X '4

Controller 4 0 0 22

Scanner 24 0 ' 0 2 4

6e "asic /eight 8oment 14;'! X 3!' '

/ith the 6e "asic /eight and 8oment; The C.G. can e calculated as follosJ

C.G. O T8 O 3!';' O 24.'1M

T/ 14;'!

The re)ised /eight and Centre of Gra)ity Schedule ill stateJ

"asic /eight J 14;'! l.

Centre of Gra)ity J 24.'1M aft of the Reference :atum

E+67,e 2J Aanitrol 9eating unit of eight 14 l. is remo)ed from fuselagestation ! and re0fitted at station 1%.



We*0:t ;,< A/6 ;*n< 'o6ent ;* *n<

riginal &ircraft 14;' X 2 X 3%

Item remo)ed 0 14 0 3 X %

Item replaced X 14 X % X 1 1

6e "asic /eight 8oment 14;' X 3' 22

/ith the "asic /eight unchanged; the C.G. position ill eJ

T8 O 3' 22 O 2!.3T/ 14 '

".12LOADING OF AIRCRAFT

The Commander of an a@c registered in the #nited Eingdom must satisfy himselfthat the load carried is of such a eight and is distriuted and secured so that itmay e safely carried on the intended flight. To ensure this; the (ariale and

:isposale 5oads must e added to the "asic /eight of the a@c and the Total/eight and C.G. position calculated. If the a@c e-ceeds % $g 8T/& or has aseating capacity of 12 or more persons; the loading is ased on assumedeights for persons and aggage; otherise the actual eights must e used.

L+/0e P+ssen0e/ +n C+/0o A*//+@t. /ith these aircraft the moment of itemssuch as fuel; passengers and cargo are considerale and calculation of C.G.complicated. In addition to longitudinal C.G. calculation; it may also e necessaryto distriute fuel and cargo in a trans)erse direction. 8ost airlines ill employ aspecialist section dealing ith loading calculations; producing a load sheet foreach flight. & typical load sheet is reproduced eloJ



We*0:t ;,< A/6 ;*n< 'o6ent;, *n1))<

CG;S'C<

#+s* We*0:t 1 21 21. 2*.2

(+/*+,e Lo+

Pilot 1! 1 1!.

6a)igator 1! 1 1!.

,ngineer 1! 12 1*.

Steard 1! 3 4*.

Cre "aggage 1 11 11.

Passenger Seats 1st 4 1% %!.

1 Tourist ! 2' 1!'.

:rin$ing /ater 2 13 32.

5ife0raft 3 41 123.

,mergency Transmitter 3 12 3.!

Ser)ice ,7uipment >food etc.? 2 4 '.

O7e/+t*n0 We*0:t 12 * 211 21 *!.! 3.

D*s7os+,e Lo+

Passengers 1st class >3? %% 1! *24.

Tourist >'3? 13 !* 2% 3!*%.!

Cargo 6o 1 hold 1 .

6o 2 hold 4 2 *.

6o 3 hold 2' 14.

6o 4 hold 4 3 14.e/o Fe, We*0:t 123*1 21 2!!3'. 33.3

+uel 6os 2 and 4 tan$s 1 1 1.

6os 1 and 3 1 2 2.

Reser)e tan$s 24 12.

T+e O@@ We*0:t 14$&1) 21) 3133$.55 2&.2

T-7*+, Lo+ S:eet

Calculate the /eights; C of G position and \ S8C in the 5oad Sheet. The S8Clength is 12M and the leading edge is 1%M aft of the datum.



".13DOCU'ENTATION



!. AIRCRAFT HANDLING STORAGE

!.1 TA9IING TOWING ASSOCIATED SAFETY PRECAUTIONS

&ircraft need to e mo)ed on the ground; eteen flights; for a )ariety ofreasons; includingJ

• 8o)ing aircraft into; or ithin hangars for maintenance

• Re0positioning a@c for ground running or storm protection.

• ,mergency remo)al of aircraft from ta-y0ay.

It is important that the aircraft is mo)ed correctly; ith the correct e7uipment soaircraft damage does not occur. Preparation for the reception of the aircraftshould e made in ad)ance of itFs arri)al. There should e ade7uate spacea)ailale for the a@c ith consideration gi)en to clearances for <ac$ing; access forcranes etc. as re7uired. &ll e7uipment re7uired for ser)icing should e a)ailaleand ser)iceale. 8any cases of damage to aircraft occur ecause of inade7uatepreparation for aircraft mo)es and poor $noledge of the correct procedures.

• The aircraft should e in a fit condition to mo)e. The ra$es should e

ser)iceale and electrical poer should e a)ailale if re7uired; for lights andindications in dar$ or poor light.

• The route of the proposed mo)e should e free from ostructions such asser)icing platforms; passenger steps; )ehicles and any other ser)icinge7uipment. Consideration should also e gi)en to foreign o<ects along theroute; that may e pic$ed up y tyres and cause damage >+..:.?

• 8o)ing aircraft is a team effort and memers of the mo)ing team should efully con)ersant ith their assigned tas$s. They should e ade7uately riefedas to their indi)idual responsiilities y the person in charge >I@C? the mo)e.This applies e7ually to re0positioning a light aircraft in the hangar or mo)ing a

%4% around 9eathro.• The e7uipment and method of mo)e should e correct. The maintenance

manual ill list the correct e7uipment to use.

• &ll toing limitations should e oser)ed. These should e stated in themaintenance manual under Mground handlingM. ,-amples of limitationsinclude 8inimum turning radii and disconnection of noseheel steeringsystem on certain a@c.

• Clearance from &ir Traffic Control may e re7uired for the mo)e.

!.1.1'O(ING 'ETHODS

6ormal mo)ing methods of mo)ing aircraft on the ground areJ

• "y hand y pushing and steering arm.

• "y tractor; using a toing arm or ridle and steering arm.

• Ta-iing.



!.1.1.1 'o*n0 - H+n =*t: Stee/*n0 A/6

This method is generally used for mo)ing small aircraft small distances. Careshould e e-ercised during the mo)e to a)oid damage to the structure;particularly on aircraft constructed from ood and faric. n aircraft fitted ith anose0heel; a steering arm is fitted to guide the aircraft and the mo)ing forceapplied to strong parts of the aircraft. It is generally etter to push the aircraftac$ards; since the leading edges are stronger than the trailing edges. It is alsopermitted to push at the undercarriage struts and ing support struts. &reaFs to

a)oid include flying controls; propellers and ing and tailplane trailing edges. naircraft ith steerale nose heels; connected to the rudder pedals; care shoulde ta$en not to e-ceed the toing limit; hich may e mar$ed on theundercarriage leg. n this type of aircraft the rudder controls should not eloc$ed during toing. If the aircraft is fitted ith a tail s$id; it is customary to liftthe tail clear of the ground; ensuring the propeller is positioned hori=ontally anddoes not stri$e the ground.

!.1.1.2 'o*n0 s*n0 + #/*,e +n Stee/*n0 A/6

This method is sometimes used hen the aircraft is to e mo)ed o)er une)en orsoft ground. This ould cause an unnecessary strain on the nose undercarriage

if normal toing procedures are used. In this method a special ridle is attachedto specific points on each main undercarriage and a steering arm is attached tothe nose undercarriage. The aircraft is normally toed ac$ards using a tractorattached to the ridle. It is normal to to the aircraft ac$ards as this reducesthe stress on the ea$er nose undercarriage. If toing points are not a)ailale;ropes may e passed round the legs as near to the top as possile; ta$ing carenot to foul on ad<acent pipes or structure. & separate tractor should econnected to each main undercarriage and steering carried out using the steeringarm.

!.1.1.3 To=*n0 A*//+@t

This is the normal method used on large aircraft. The aircraft is normally toedith a suitale tractor or tug and the correct toing arm. & person familiar iththe a@c ra$e system should e seated in the coc$pit to apply the ra$es in anemergency. The ra$es should not normally e applied unless the aircraft isstationary. The 8aintenance 8anual ill normally specify details of the toingarm and any limitations on toing. n many aircraft ith nose0heel steering; itis normal practice to disconnect the aircraft steering efore toing. This enalesthe aircraft steering limits to e e-ceeded.

!.1.1.4 P/e+t*ons to Ose/e =:en To=*n0 A*//+@t

• Toing speed should e $ept to a safe le)el at all times >al$ing pace is a

safe limit?• & steering limit is often imposed so that the radius of turns is $ept ithin

specified limits. This ill minimise tyre scruing and reduce the tistingloads on the undercarriage. It is usual to to the aircraft forards in astraight line after e-ecuting a turn; to relie)e stresses uilt up in the turn. Thesteering limit is often shon y mar$s painted on the fi-ed part of the noseleg; ut may sometimes e o)ercome y disconnection of a pin <oining thetor7ue lin$s

• Personnel >suitaly riefed? should e positioned at the ing tips and tailhen manoeu)ring in confined spaces; so ostructions may e a)oided. neperson shall e super)ising the aircraft mo)ement >not the tractor dri)er? and

should e positioned so that all memers of the team may e oser)ed.



• Particular care should e gi)en hen toing sept ing aircraft to Fing tipgrothF. This is the tendency of the sept ing to FgroF in a turn.

• "efore commencing the toing operation; the ra$e system should echec$ed and ra$e accumulator charged if necessary. "ra$e pressureshould e carefully monitored during the mo)e.

• 5arge multi0engine aircraft ill usually e toed ith special purpose tug anda suitale toing arm fitted ith a shear pin; designed to shear if apre0determined toing load is e-ceeded.

• In an emergency it may e necessary to mo)e an aircraft from the runayhile it has one or more deflated tyres. Pro)ided there is one sound tyre onthe a-le the aircraft may e toed to the maintenance area; ut sharp turnsmust e a)oided and toing speed $ept to a minimum. If there are no soundtyres on the a-le; the aircraft should only e mo)ed the shortest distance toclear the acti)e runay and ser)iceale heels fitted efore toing. &fterany tyre failure; the associated heel and other heels on the same a-leshould e inspected.

!.1.1.5 T+**n0 A*//+@t

If an aircraft is to e ta-ied rather than toing or pushing a 7ualified pilot illnormally e used. It is unusual for aircraft to need ta-iing. Sometimes it oulde re7uired to confirm a prolem ith the landing gear or to test that a heel)iration prolem. The main contact an engineer has concerning ta-iing is togi)e signals to the pilot. /e call this marshallingF.

8arshalling is a techni7ue used to pass information in the form of signals to thepilot; assisting him@her to ta-y or par$ the aircraft safely. The pilot remains incharge of the aircraft. The aim of marshalling is to assist in safe manoeu)ring ofthe aircraft on the ground. 8arshalling signals are also used during groundrunning of engines and hen toing aircraft. To do this effecti)ely; themarshaller mustJ

• #nderstand the aircraftFs manoeu)ring limitations >Refer to 8aintenance8anuals?.

• &ppreciate the aircraft si=e and understand sept ing groth >Ifapplicale?.

• Gi)e clear and correct signals.

• 6e)er ta$e ris$s.



!.1.1." Gene/+, '+/s:+,,*n0 Po*nts

• 8arshalling signals may e gi)en ith hands or marshalling ats y day o/marshalling ands; y night.

• 8arshallFs should identify themsel)es to the pilot y raising their hands anda)ing them in a circular motion. Identification may also e assisted if the

marshaller ears distincti)e coloured garments. Typically; a marshaller mayear a yello or F:ay0gloF aistcoat or hite o)eralls. nce the attention ofthe pilot is gained; the marshaller should direct the pilot ith a series of clearstandard signals.

• 8arshallFs should position themsel)es forard of the aircraft and in line iththe port ing0tip; ithin the pilotFs )ision.

• It is safer for the marshaller to e positioned ell forard of the aircraft andallo the aircraft to ta-i on to him@her. & marshaller al$ing ac$ards oulde unaare of hat is going on ehind.

• If the area has ostructions; ing tip safety personnel should indicate

clearance y use of standard signals.• /hen marshalling at night ith ands; alays carry a spare and. If one

and fails; the other should e sitched off and the pilot should stop until theunser)iceale and is replaced and marshalling recommences.

!.1.1.! '+/s:+,,*n0 S*0n+,s

There are marshalling signals for many situations and types of aircraft. Some ofthe important signals all aircraft engineers need to $no are as follosJ

• St+/t En0*nes 0 5eft hand o)erhead ith appropriate numer of fingers

e-tended to indicate engine to e started. Circular motion of right hand athead le)el.

• Sto7 En0*nes >Cut engines? 0 ,ither arm and hand le)el ith shoulder;hand mo)ing across throat; palm donard. The hand is mo)ed sideaysith the arm remaining ent.

• 'oe Fo/=+/ 0 &rms a little apart held out in front at shoulder height andrepeatedly mo)ed upards and ac$ards >ec$oning?

• T/n Le@t >PilotFs 5eft? 0 Point right arm donards. 5eft arm mo)edrepeatedly upards and ac$ards; speed of mo)ement indicating rate ofturn.

• T/n R*0:t 0 Point left arm donards. Right arm mo)ed repeatedlyupards and ac$ards etc.

• STOP 0 &rms crossed ao)e the head ith palms facing forard. #rgentstop ould e indicated y repeated crossing and uncrossing.

• #/+es On 0 "y day; arms ao)e head ith palms forard and fingersraised. Then fist closed again ith palms toards aircraft.



!.2 ACKING CHOCKING SECURING ASSOCIATED SAFETYPRECAUTIONS

&ircraft may need to e <ac$ed for a )ariety of purposes. These may includecomponent changes; retraction tests; eighing of the aircraft and aircraft riggingtests.

&ircraft Aac$ing Points Care needs to e ta$en hen <ac$ing; to a)oid damage toaircraft or e7uipment; <ac$ing points are pro)ided in the ings and fuselage; atstrong points; to enale the hole aircraft to e lifted; and; usually at the noseand main undercarriages to enale indi)idual heels to e changed. Someaircraft re7uire a Aac$ing pad to e fitted to each <ac$ing point; hile in some; the <ac$ing pads are uilt into the structure. Special <ac$ing adapters and eamsmay e a)ailale to lift indi)idual a-les. In all cases; the 8aintenance 8anualshould e consulted so the correct e7uipment and procedures may e used.

!.2.1SPECIAL CONSIDERATIONS

"ecause of the position of the <ac$ing points; the C of G of some aircraft may eell ehind or in front of the main <ac$ing points. It may e necessary to addallast forard or rear of the <ac$ing points or to chec$ the fuel load of the

aircraft; to ring the centre of gra)ity ithin safe limits as specified in the8aintenance 8anual.

,ach <ac$ing point may ha)e a load limit hich; if e-ceeded; could result instructural damage. To a)oid e-ceeding this limit it may e necessary to fithydraulic or electric load cells. &ny special re7uirements should e listed in the8aintenance 8anual.

8icro0sitches fitted to the undercarriage legs and operated y the e-tension ofthe shoc$ asorers >eight0on sitches?; are used to operate )arious electricalcircuits. This operation may not e desirale so circuits should e isolated; ytripping circuit rea$ers or remo)ing fuses as necessary.

&ircraft should alays e as structurally complete as possile efore <ac$ing; It isessential that any stressed panels hich ha)e een remo)ed are re0fitted.+ailure to do this may result in distortion or failure of the structure.

!.2.2AIRCRAFT ACKS

&ircraft <ac$s are intended for raising and loering loads and should not e usedfor supporting the loads for long periods. /here a load must remain raised for along period; it should e supported on loc$s or trestles after it has een <ac$edto the re7uired height. The most common types are the pillar; trolley; tripod;ipod and 7uadruped hydraulic <ac$s. There are se)eral si=es of <ac$ ithcapacities from 4 0 2 tons or more.

P*,,+/ H-/+,* + 0 The <ac$ consists of a cylinder assemly; fluid containerand a hydraulic pump; hich hen operated; forces fluid from the container intothe cylinder and raises the ram. & release )al)e is fitted hich; hen openedcauses the fluid in the cylinder to return to the container and the ram to descend."ecause of possile hydraulic failure; some <ac$s are pro)ided ith a mechanicalloc$ing collar hich hen ound don ill pre)ent the <ac$ from loering. &nair@filler )al)e hich )ents the return side to atmosphere may also e pro)ided.This should alays e open hen the <ac$ is operated.



St+n+/ P*,,+/ o/ #ott,e +

!.2.2.1 T/*7o #*7o +n %+/7e +s

These <ac$s are used to raise an aircraft for )arious ser)icing operations. Theirmethod of operation and hydraulic mechanism is similar to the pillar <ac$. Theyconsist of a hydraulic unit supported y a numer of legs in the configurationsshon. "ecause of the prolems in)ol)ed in raising an aircraft and to a)oidin<ury to personnel or damage to the aircraft; care should e ta$en to use thecorrect type of <ac$ as stated in the maintenance manual. ,ach <ac$ should eused ith the correct adapter head.



The t/*7o + comprises a hydraulic unit ith three e7ually spaced legs. The <ac$ is designed for a )ertical lift only and not for a lift in)ol)ing lateralK mo)ementof the <ac$; such as raising one side of the aircraft for a heel change. Theresulting side thrust may cause any one of the folloingJ

Serious damage to the ram due to the ending load

• :istortion of the Aac$ legs

• :amage to the aircraft due to <ac$ head slipping out of the <ac$ing pad

• Shearing of the <ac$ing pad fastener

• The ser)iceale tyre may e dragged sideays

To change a single heel; a pillar <ac$ may e used; to tripod <ac$s may eused to raise the complete aircraft or a ipod <ac$ may e used. The ipodarrangement o)ercomes the limitations of the tripod <ac$ for an FarcF lift. n thistype of <ac$; to fi-ed legs pro)ide the support and a third trailing leg follos thelift and steadies the load during the lift. The ma-imum angle of arc should not emore than ! degrees.

The B+/7e + is used more commonly as it possesses the ad)antages ofoth types of <ac$. To legs are fi-ed and to ad<ustale. This <ac$ may e

used as a ipod <ac$ y remo)ing ad<ustale leg; or an ad<ustale stale <ac$ iththe e-tra leg added. &ll four legs may e loc$ed solid y slight ad<ustment ofoth ad<ustale legs. Transportation heels are often permanently attached tolarge <ac$s or as detachale units on other <ac$s. These facilitate easymo)ement of the <ac$s that ould otherise need to e dragged around thehanger. &lternati)ely; <ac$s can e dismantled for transportation.

Uses o@ ot:e/ +s on +*//+@t +/e s:o=n *n t:e *+0/+6 e,o=.



!.2.3ACK 'AINTENANCE GENERAL NOTES

• The <ac$s should alays e positioned correctly and the load raised andloered gradually.

• &ll <ac$s should e stored in the fully retracted position.

• Eeep <ac$s clean and free from corrosion. 5uricate mo)ing parts regularlyand e-ercise the <ac$ if not used fre7uently.

• Aac$ replenishment is usually through the air )al)e up to the le)el of theottom of the air )al)e. 5o oil le)el is indicated y inaility to lift toma-imum height. )er filling is indicated y lea$age of oil hen the <ac$ isfully e-tended.

!.2.4AIRCRAFT ACKING PRECAUTIONS

&s a safety precaution; small aircraft should normally e <ac$ed inside a hanger.5arger aircraft may e <ac$ed outside pro)ided they are headed into ind; the <ac$ing surface is le)el and strong enough to support the eight and any specialinstructions stated in the 8aintenance 8anual oser)ed. There should also e ama-imum ind speed stated for <ac$ing outside. The aircraft to e <ac$ed shoulde choc$ed fore and aft and the ra$es o@@ . If the ra$es ere left on; stresscould e introduced to the landing gear or aircraft structure as the aircraft israised.



!.2.5ACKING PROCEDURE

The folloing procedure ill generally ensure satisfactory <ac$ing of most aircraft;ut account should e ta$en of any additional precautions specified in themanual. ne person should co0ordinate the operation and one person shouldman each <ac$ing point. n larger aircraft a le)elling station ill also need to emanned and all memers of the team may need to e in radio or telephonecommunication ith the co0ordinator.

1. Chec$ that the aircraft eight; fuel state and centre of gra)ity are ithin the

specified limits.2. 9ead the aircraft into ind if it is in the open; choc$ the main heels fore and

aft and release the ra$es.

3. ,nsure that there is ade7uate clearance ao)e e)ery part of the aircraft andthat there is clearance for lifting cranes or other e7uipment that may ere7uired.

4. Connect earth cale to the earth point on the aircraft.

. Install the undercarriage ground loc$s

!. +it <ac$ing pads to the <ac$ing points and adapters to the <ac$s as re7uired.+it load cells if needed.

%. Position the <ac$s at each <ac$ing point and chec$ the <ac$s are ad<ustedcorrectly i.e. release )al)e closed; <ac$ ody )ertical and eight e)enlydistriuted aout the legs hen the adapters are located centrally in the <ac$ing pads and the eight of the aircraft is <ust eing ta$en y the <ac$s.

'. Remo)e the choc$s and sloly raise the aircraft as e)enly as possile./hilst <ac$ing; the loc$ing collars should e ound don $eeping them closeto the ody of the <ac$. /hen the aircraft is raised to the correct height; theloc$ing collar should e tightened don.

*. Place supports under the ings and fuselage as indicated in the8aintenance manual.

1. & pillar >ottle? <ac$ and an adapter are often used for raising a single

undercarriage for changing a single heel. &lternati)ely a trolley <ac$ orstirrup <ac$ may e used. The remaining heels should e choc$ed topre)ent aircraft mo)ement; and it may e specified that a tail support islocated hen raising a nose undercarriage. The <ac$ should e raised onlyenough to lift the unser)iceale heel clear of the ground.

!.2."LOWERING AIRCRAFT

"efore loering the aircraft to the ground; e7uipment; or$ stands etc. should emo)ed clear of the aircraft to pre)ent inad)ertent damage. The heels should erotated y hand to ensure the ra$es are off. The <ac$s should e loeredtogether y opening their release )al)es; and; the loc$ing collars >if used?

unscreed hilst the <ac$s are loered; and $ept ithin 2M of the <ac$ ody. The <ac$s should e fully loered +@te/ the aircraft is resting on itFs heels and therelease )al)es closed.

S+@et- Note 0 n no account should the top of the <ac$s e handled until the <ac$ is clear of the aircraft. It is common for the aircraft shoc$ asorers to stic$and suddenly collapse resulting in damage to e7uipment or serious in<ury to partsthat might e eteen the aircraft and <ac$. &fter the aircraft is loered and the <ac$s remo)ed; the <ac$ing pads and adapters should e remo)ed and thechoc$s placed in position. &ny fuses or circuit rea$ers should e re0set in theircorrect position.



!.2.!TRESTLES

These are pro)ided to support to aircraft structures >main planes; fuselages etc.?and may also e used to support the complete aircraft. (arious types area)ailale including plain ooden trestles that are purpose uilt and notad<ustale. Trestles should only e used at designated strong parts of thestructure. It ill normally e shon in the 8aintenance 8anual here theyshould e positioned. 5ines are often painted on the aircraft to sho here thetrestle eam is positioned.

Un*e/s+, T/est,e 0 This trestle is made up from lengths of angle iron; olts andnuts; and has to <ac$ing heads. "y using different lengths of angle iron; trestlesof )arious si=es can e produced. The ooden eam across the <ac$ing headsmay e replaced y a ooden former; cut to the cur)ature of the component itsupports. Padding is normally attached to the former to pre)ent damage to theaircraft finish. The to <ac$ing heads; hich are hand operated scre <ac$s;enale the eam to e ad<usted to suit the angle of the component.

NoteJ &lthough the trestles ha)e F<ac$ing headsF; they should only e used forsupporting a load; not for attempting to raise parts of the aircraft. :amage maye caused to the aircraft if attempts are made to to do any more than support thestructure.

T+*, T/est,e 0 This trestle is not suitale for hea)y loads and must only e usedfor supporting a load )ertically. &d<ustment in height may e made y rotatingthe indlass type nut. &s in the uni)ersal trestle; the eam may e replaced y ashaped former to suit the contours of the aircraft.

S,*n0*n0 0 Slings may e re7uired for lifting )arious parts of an aircraft duringmaintenance; repair; dismantling and assemly. Sometimes a complete aircraftmay need to e lifted for transportation or to clear a runay 7uic$ly.

The use of the correct e7uipment for lifting aircraft parts ill minimise the ris$ ofdamage to the aircraft and personnel. & list of special e7uipment is usually in thefront of the maintenance manual. This list ill usually include special slings to e

used on the aircraft and any other special e7uipment or tools re7uired.Slings may e of the three0point type as used for lifting0main planesK other types;used for lifting engines; fuselages or other large items may e fitted ith spreaderars or struts. "efore remo)ing a main plane; the opposite main plane must esupported ith trestles. To attach a sling; some aircraft ha)e special slingingpoints ith threaded holes in the airframe hich are used to fit the eye or for$0end olts of the sling. These holes are normally sealed hen not in use ithremo)ale plugs. &s an alternati)e to scre in fittings; some slings are used incon<unction ith strong straps that pass under the component to e lifted.

!.2.$LIFTING TACKLE

/ire rope; chain or fire rope may e used for lifting purposes. "efore use; thetac$le should e inspected to ensure that it is ser)iceale; of the correct typeand; hen used; that the Safe /or$ing 5oad >S./.5.? is not e-ceeded. TheS./.5. may e stated on a rass tally attached to the lifting sling. This rass tallyshould ne)er e remo)ed from the sling.

/ire Rope is used in cranes; hoists; gantries and )arious slings. "efore use; theire rope should e inspected for ear; corrosion; ro$en ires etc. The splicesand their attachments should also e inspected for ser)iceaility. In use; careshould e ta$en that the rope does not $in$ under load. "efore multiple leg irerope slings are used; they should e laid out on the floor to ensure shac$les arecorrectly fitted and the fittings are not tisted. Enotting of ropes to shorten them

is prohiited.



Chains are used in cranes; and )arious types of sling. "efore use; they must einspected for crac$s; flas; distortion; e-cessi)e ear and Fsoc$etingF. This latterdefect is the name gi)en to the groo)es produced in the ends of lin$s hen thelin$s ear against each otherK any reduction in diameter in e-cess of a gi)enfigure >usually 1\? ill render the chain unser)iceale.

+ire rope slings may e used for lifting lighter components such as propellers.These slings use natural fires such as sisal or hemp or nylon fires. They muste inspected for frayed strands; pulled splices; e-cessi)e ear and deterioration.The slings hen not in use; should e hung on pegs in a sheltered position freefrom dampness. Immediately efore use; the rope should e opened up yslightly untisting the strands to ensure they are not damaged or mildeedinternallyJ a damaged or mildeed rope sling should not e used; it must edestroyed. In addition to efore0use chec$s on the rope; all loaded componentssuch as pulley loc$s; shac$les; pins; spreader ars; hoo$s etc. are to einspected for e-cessi)e ear; crac$s and flas. 8o)ing parts must e luricatedperiodically.

/ire rope slings are normally treated against corrosion y immersion in oil andthe surplus oil iped off; ut this treatment must not e applied to slings used foro-ygen cylindersJ they must alays e free from oil or grease.

,-cept under e-ceptional circumstances; slings should not e made up locally.5ifting tac$le must e inspected for ser)iceaility efore use and only slings fittedith inspection tallies should e used. 6atural fire or nylon rope slings usuallyha)e a specific life and must e destroyed y cutting into short lengths at the endof their life or hen found defecti)e.

!.2.$.1 P/e+t*ons W:en Us*n0 L*@t*n0 T+,e

• The safe or$ing load must not e e-ceeded.

• :o not lea)e a suspended load un0attended.

• :o not al$ or or$ under a suspended load.

• :o not to the hoist at greater than al$ing pace.

• :o not to the hoist; other than y hand; hen a load is suspended from thelifting hoo$.

• :o not allo the load to sing; especially hen it is eing hand toed.

• &)oid using a hoist or crane on soft ground.

• :o not use a crane or hoist if the lifting rope shos sign of fraying.

!.3 PARKING SECURING AIRCRAFT

/hen an aircraft is out of ser)ice and in the open it should e secured againstinad)ertent mo)ement and protected against ad)erse eather conditions. Theoperations recommended in the rele)ant 8aintenance 8anual depend on thetype of aircraft; the length of time it ill e out of ser)ice and the pre)ailing orforecast eather conditions.

The folloing points should e considered hen par$ing the aircraftJ

• "eteen flights it is usually sufficient to apply the par$ing ra$es; loc$ thecontrol surfaces and choc$ the heels; ut in a strong ind light aircraftshould e headed into the ind. 5ight aircraft ithout heel ra$es shoulde headed into ind and their heels chec$ed front and rear.



• +lying controls on many aircraft are loc$ed y mo)ement of a le)er in thecoc$pit@cain; hich is connected to loc$ing pins at con)enient positions inthe control runs or at the control surfaces. /hen this type of control loc$ isnot fitted; loc$ing attachments may ha)e to e fitted to the control column andrudder pedals. & more positi)e method is to use e-ternal control surfaceloc$s that pre)ent control surface mo)ement and thus pre)ent strain on thecontrol system. &ll e-ternal loc$s should ha)e suitale streamers attached;to ma$e them more )isile.

• If an aircraft is to e par$ed o)ernight or for longer periods in the open; thenadditional precautions should e ta$en to guard against the effects of ad)erseeather. The undercarriage ground loc$s should e fitted; all openings suchas static )ents; engine and cooling air inta$es should e lan$ed to pre)entingress of dirt; irds; insects and moisture. &ll fittings such as pitot head andincidence indicators should e co)ered. /hen se)ere eather is anticipatedit is recommended that co)ers for coc$pit; canopy and heel are fitted ifa)ailale. "lan$s and co)ers should not e left in position hen the aircraft isprepared for ser)ice. Ser)icing instructions should include a pre0flight chec$to ensure that all co)ers etc; are remo)ed.

!.3.1SECURING PICKETING 'OORING

In certain eather conditions; particular in the case of high inds; it ould erecommended that the aircraft e par$ed in a hangar. If they must e left outsidesmaller aircraft may need to e tied don. The aircraft may e fitted ithpic$eting rings or attachment points at the ings and tail or ad<acent to theundercarriage legs. If outside the aircraft should alays e par$ed nose intoind and secured from the pic$eting points to suitale ground anchor points>hea)y concrete loc$s or specialised scre pic$ets?. Cale or nylon rope ofade7uate strength should e used here possile; ut if a natural fire rope isused >sisal or hemp?; sufficient slac$ must e left to allo for shrin$age in dampconditions. &dditional pic$eting from the undercarriage legs may erecommended in strong inds and; if so; care should e ta$en not to damage

any pipelines or e7uipment attached to the legs or heels.

!.3.2TYPICAL S'ALL AIRCRAFT PROCEDURE

/hen mooring the aircraft in the open; head the aircraft into the ind if possile.Secure control surfaces ith the internal control loc$ and set ra$es. Caution 0:o not set the par$ing ra$es in cold eather hen accumulated moisture mayfree=e the ra$es or hen the ra$es are o)erheated. &fter completion; proceedto moor the aircraft as follosJ

• Tie ropes; cales; or chains to the ing tie0don fittings located at the upperend of each ing strut. Secure the opposite ends of the ropes; cales orchains to ground anchors. Secure a tie don rope >no chains or cales? to

the e-posed portion of the engine mount and secure opposite end to aground anchor.

• Secure the middle of a rope to the tail tie0don ring. Pull each end of therope at a 4 degree angle and secure to a tie0don point either side of tail.

• Secure a control loc$ on pilot control column. If control loc$ is not a)ailale;tie the pilot control ac$ ith a front seat elt. These aircraft are e7uippedith a spring0loaded steering system that affords protection against normalind gusts. 9oe)er; if e-tremely high inds are anticipated; additionale-ternal loc$s may e installed.



!.3.2.1 L+/0e A*//+@t

These may only re7uire pic$eting in )ery strong ind conditions. The ma-imumind0speed ill normally e stated in the 8aintenance 8anual >including gustinginds?. The aircraft should e headed into ind and the par$ing ra$es applied.Cales or chains should e attached from the aircraft pic$eting points to preparedanchorageFs. In some cases the pic$eting cales are special components andinclude a tension meter that is used to apply a pre0load to the cale.

!.3.2.2 He,*o7te/s

In addition to the ao)e re7uirements; the rotor lades should e tetheredhene)er possile; since e)en light gusting inds can cause damage to thelades if free to flap. The collecti)e pitch le)er should normally e loc$ed in thefully fine position and the rotor ra$e applied. Rotor head and lade co)ersshould also e fitted if the0helicopter is par$ed o)er night. If high inds aree-pected; they should e par$ed in a hangar and@or the rotor lades should efolded. n many helicopters the lades are tethered y aligning one lade alongthe tail cone; loc$ing the collecti)e pitch le)er in fine pitch; and applying the tipco)ers to each lade; pulling them against the stops. ,ach lade may then elashed to itFs respecti)e pic$eting point.



!.4 GROUND DE>ICING ANTI>ICING

!.4.1GROUND DE>ICING OF AIRCRAFT

Ice formation on an aircraft on the ground may result from a numer of causesJ

• :irect precipitation from rain; sno; frost etc.

• Condensation free=ing on e-ternal surfaces of integral tan$s folloingprolonged flight at high altitude.

• &fter ta-ing through sno or slush; ice may accumulate on landing gear;forard facing surfaces and under0surfaces.

The formation of ice on aircraft structures ill ha)e many ad)erse effects. Theseill e descried in the systems module. They ill; if alloed to remainJ

• :ecrease aerofoil lift

• Increase aerofoil drag

• Increase eight

• :ecrease engine thrust

• +ree=ing of moisture in control hinges

• +ree=ing of micro0sitches; affecting systems such as the landing gearretraction

• Ingestion of ice into the engine

Ground de0icing must not only remo)e ice deposits efore ta$e0off ut mustpre)ent them from reforming until the aircraftFs on ice protection systemecomes effecti)e. This may not occur until the aircraft is estalished on theclim0out.

Complete protection against ground icing can only e pro)ided y $eeping theaircraft in a heated hangar until re7uired for flight ut this is often impossile andusually impracticale. Remo)al of sno and ice 7/*o/ to ta$e0off and a$noledge of methods of ground de0icing is essential. There ha)e een manyaircraft accidents and incidents attriuted to poor ground de0icing procedures.

!.4.2DE>ICING AND ANTI>ICING

It is important to point out at this point the difference eteen the to terms. :e0icing in)ol)es remo)al of ice; sno or frost already accumulated on the aircraft. &nti0icing is concerned ith pre)ention of itDs formation. If icing conditions areanticipated; an attempt should e made to protect the aircraft.

!.4.3'ETHODS OF DE>ICING

Ground de0icing may e accomplished y mechanical methods >rush or ruers7ueegee? or y using F/eeJ*n0 Po*nt De7/ess+nt >+P:? compounds; the tomethods often used in con<unction ith one another. There are to main typesof +P: compoundsJ

• T-7e 1 ;nt:*ene< 0 These fluids ha)e a high glycol content ut ha)e alo )iscosity. They pro)ide good de0icing performance ut only limitedprotection against re0free=ing.

• T-7e 2 ;t:*ene< 0 These fluids ha)e a minimum glycol content ofappro-imately \ and; due to a thic$ening agent; are ale to remain on theaircraft surfaces for longer periods. The de0icing performance is good and; inaddition; pro)ides protection against re0free=ing and@or uild up of furtheraccretion hen e-posed to free=ing precipitation.



!.4.3.1 T/e+t6ent o@ F/ost De7os*ts

+rost deposits are est remo)ed y the use of a frost remo)er or; in se)ereconditions; a de0icing fluid such as K*,@/ost A#C >&ircraft "arrier Compound?.These fluids usually contain either ethylene glycol and isopropyl alcohol ?diethylene glycol >or propylene glycol? and isopropyl alcohol.

This process is not lengthy and; pro)ided it is applied ithin to hours of flight;one application is usually sufficient.

Note 1 0 :e0icing may ad)ersely affect gla=ed panels or paint finish. +or thisreason only fluids recommended y the manufacturer should e used and anyinstructions for their use should e strictly oser)ed.

Note 2 0 :e0icing fluids; particularly those ith an alcohol ase; may causedilution or complete ashing out of oils and greases from control earings etc.alloing ater to enter hich may suse7uently free=e; <amming controls. :e0icing spray no==les should not e directed at lurication points or sealedearings.

9ot air loers may e used to remo)e frost. 8elted frost should e dried upand not alloed to accumulate in hinges; micrositches etc. here it may re0free=e.

!.4.3.2 Re6o+, o@ Ie +n Sno= De7os*ts

:eep et sno should e remo)ed ith a rush or s7ueegee ta$ing care not todamage aerials; pitot proes; stall arning )anes; )orte- generators etc; hichmay e co)ered in sno. The sno should also e cleared from )ents; inta$es;control hinges and control surface gaps.

5ight dry sno should e lon off using a cold air loer. 9ot air is notrecommended as it may melt the sno hich may accumulate and free=ere7uiring further treatment.

8oderate to hea)y ice deposits or residual sno should e cleared ith de0icing

fluid applied y spraying.Note 1 0 6o attempt must e made to remo)e ice y the use of force to rea$

the ond.

Note 2 0 :e0icing should proceed symmetrically to pre)ent e-cess eight onone side of the aircraft.

!.4.3.3 Co, FL* S7/+-

This is the simplest method of applying de0icing fluid ut suffers from thefolloing disad)antagesJ

• In )ery se)ere conditions one application of cold fluid may not e sufficient to

remo)e all deposits. "rushing; folloed y a second or third application maye necessary

• &s the ice and sno melts the de0icing fluid ecomes diluted; ecomes lesseffecti)e and may free=e again 7uite 7uic$ly. This may e dangerous ifdiluted fluid is alloed to run into control surface and landing gearmechanisms.



!.4.3.4 Hot F,* S7/+-

This method has een adopted specifically to reduce turn round time. The +P:fluid is mi-ed ith ater in proportions to suit pre)ailing eather conditions andheated in a static unit to a temperature of %NC. It is then transferred to aninsulated tan$ on a moile unit hich may then e dri)en to the site ofoperations. The fluid is normally sprayed on to the aircraft at a temperature of%NC and at a pressure of 1 psi y use of spray lances. The no==le of thelance is held close to the aircraft s$in to pre)ent heat losses. The heat transfers

to the s$in of the aircraft; rea$ing the ice ond; and large areas of ice may eflushed aay y turning the no==le sideays. The film of fluid left on the s$in hasonly een slightly diluted eyond its original dilution and is effecti)e in pre)entingfurther ice formation.

!.4.3.5 Hot W+te/ De>**n0

This method must not e used elo 0%°C and may need to e performed in tosteps.

1. Sno and ice is normally remo)ed initially ith a <et of hot ater not

e-ceeding *°C.

2. If necessary a light coating of de0icing fluid is then sprayed on immediately

>ithin 3 minutes? to pre)ent re0free=ing.

!.4.4SAFETY NOTES

• 9igh pressure sprays may cause damage to pitot0static proes and othersensing de)ices

• Co)ers and ungs should e fitted during de0icing operations to pre)entingress of fluid into air inta$es; drains; )ents and ram air inta$es

• 9igh pressure sprays may cause erosion of the aircraft s$in. Consult theappropriate 8aintenance 8anual for manufacturers recommended ma-imumimpingement pressure.

!.4.5ANTI>ICING

/hen used for anti0icing the +P: fluid should e sprayed on to the aircraft coldand undiluted either e@o/e the onset of icing or after hot de0icing has eencarried out. The fluid film ill pre)ent ice and sno from stic$ing to the aircrafts$in and; gi)en time; ill melt any fresh precipitation. The time for hich the fluidremains effecti)e; $non as the Fhold o)erF time; is gi)en in the tale on thefolloing page.

Notes8

• #nder e-treme cold conditions it may e necessary to heat the fluid >!NCma-? to gi)e it sprayaility.

• 6o significant increase in holdo)er time is achie)ed y strengthening the mi-of type I >&,&? fluids.

• Stations using Eilfrost ill normally pro)ide a mi- of 0@ or !@4. It may edifficult to get stronger mi-es at short notice unless the temperatureconditions at the stations in)ol)ed are elo limits for that mi-.



G*e to Ho,oe/ T*6es

A6*ent

Te67 C

We+t:e/ Con*t*ons T-7e II ;AEA< @,*s

T-7e I F,*s;See note 2<

F/ost F/eeJ*n0@o0

Ste+-Sno=

F/eeJ*n0R+*n

R+*n ono, so+e=*n0

Ant*>I*n0 De>I*n0

1)) Co,;See Note 1<

!525 ;:ot< ")4) ;:ot< 5)5) ;:ot<

Aoe ) ]

]

]

]

]

' hrs

3 hrs

1 hr

2 min

hrs

2 hrs

4 min

1 min

4 hrs

1U hr

3 min

% min

3 hr

1V hr

3 min

min

4 min

3 min

1 min

min

) to ! ]

]

]

]

' hr

1V hr

4 min

2 min

hr

1 hr

3 min

1 min

4 hr

min

2 min

min

3 hr

4 min

1 min

3 min

3 mins

1 mins

1 mins

3 mins

>$ to

>1)

]

]

]

' hr

1V hr

4 min

hr

1 hr

3 min

4 hr

min

2 min

3 mins

1 mins

1 mins

>11 to

>14

]

]

]

' hr

1V hr

4 min

hr

1 hr

3 min

3 mins

1 mins

1 mins

>15 to

>25

]

]

]

' hr

1V hr

4 min

3 mins

1 mins

1 min



!.4."DE>ICING PASTE

ne some aircraft not e7uipped ith aerofoil or propeller de0icing systems; theuse of a de0icing paste may e specified. The paste is spread e)enly y hando)er ing; tail and propeller leading edges and pro)ides a chemically acti)esurface on hich ice may form ut not produce a ond. &ny ice hich forms islon aay y the airstream.

The paste should e re0applied efore each flight in accordance ith the

manufacturers instructions.

NoteJ Paste does not constitute an appro)ed method of de0icing otheriseunprotected aircraft for intended flights into $non or forecast icing conditions.

!.4.!INSPECTION AFTER DE>ICING OPERATIONS

The folloing inspection should e carried out on completion of a de0icingoperationJ

1. ,-ternal surfaces for signs of residual sno or ice particularly in the )icinity ofcontrol surface gaps and hinges.

2. &ll protrusions and )ents for signs of damage.

3. Control surfaces for full and free mo)ement y hand. /here this is notpossile the pilotFs controls should e used earing in mind that poeroperated controls e-ert large forces and could cause damage if any part ofthe control surface is fro=en.

4. 5anding gear mechanisms; doors; ays and heel ra$es for sno and icedeposits.

. #p0loc$s and micro0sitches for correct operation.

!. Chec$ that tyres are not fro=en to the ground. They should e freed y theapplication of hot air to the ice >not the tyre? and the aircraft mo)es to a dryarea.

%. ,ngine air inta$es for ice and sno deposits.'. +reedom of rotation of gas turine engines y hand. Restriction may indicate

icing in the compressor region and the engine should e lon through ithhot air immediately efore starting until the rotating parts are free.

*. Shoc$ asorer struts and hydraulic <ac$s for lea$s caused y contraction ofseals and metal parts.

1. Tyre pressures and shoc$ asorer pressure and e-tension.

11. ,ntry in Tech. 5og.



!.5 STORAGE

The pre)ious section dealt ith par$ing of aircraft for )arious lengths of time inad)erse eather conditions. If an aircraft is de0acti)ated for an e-tended time itill need to e protected against corrosion; deterioration and en)ironmentalconditions during storage. The folloing notes are ased on the storageprocedures applicale to "& 14! aircraft that ha)e een de0acti)ated for periodsin e-cess of 3 days up to a ma-imum of 2 years. It is not intended for the

information gi)en to e complete; <ust to gi)e the reader an idea of some of theacti)ities performed.

& list of e7uipment and materials is normally gi)en. This ill normally includeJ

• 9ydraulic fluid and luricating oils; grease

• Specialised ater displacing fluids >/: 4? corrosion pre)entati)ecompounds

• &ircraft co)ers and lan$s

• Plastic sheeting and adhesi)e tape

Generally there ould e an initial procedure; this eing repeated a specified

inter)als as shon in the tale elo. If no repeat inter)al is gi)en; the item isonly done initially.



ITE' Re7e+tInte/+,s ;+-s<

5anding Gear

Clean and dry main and landing gear ays

Chec$ landing gear for hydraulic lea$age %

5uricate main nose landing gear

Clean@Chec$ Shoc$ struts for lea$s /ipe sliding tue ithhydraulic fluid

3

Clean Gear #ploc$ 8echanisms. Protect ith grease

Clean and apply thin coat of hydraulic fluid to actuator and pistonrods

!

Spray micro0sitches and pro-imity sitches ith aterdispersion fluid

Chec$ tyre pressures and mar$ position of tyres ith date

Rotate heels one 7uarter of a term and mar$ tyre ith date

Should aircraft e stored in a hangar; deflate the shoc$ asorers.The aircraft may e manoeu)red in the hangar ith deflated shoc$asorers

%

1

+light Controls

+ully e-tend flaps

pen and tag flap )al)es and airra$e circuit rea$ers

+ully e-tend lift spoilers and install safety slee)es to all spoiler <ac$s

:epressurise hydraulic system

5uricate the flight controls

Protect flap carriages; upper surfaces of flap trac$s ith grease %

Protect all control cales accessile ith oil

Chec$ for corrosion and here found repair affected areas 3

Poer Plants

Carry out special long term storage procedure for engines 1'

NoteJ Reneal of engine long term storage is preceded y enginerun

-ygen System

Chec$ test date of o-ygen cylinders

:isconnect distriution lines from o-ygen cylinders; lan$ offpipelines and cylinder outlet connection

Chec$ cylinder pressure is ao)e p.s.i.

Remo)e cre mas$s for storage



ITE' Re7e+tInte/+,s ;+-s<

/ater /aste

:rain potale ater system

Purge potale ater system ith dry air or nitrogen

+uel System

Refuel aircraft ith fuel treated ith an appro)ed iocidal agent

&fter 24 hours; drain ater from fuel tan$s

&ir Conditioning System

Install lan$s in the ,CS ram air inlet; e-haust; &P# inta$e; &P#oil cooler; front and rear discharge )al)es

9ydraulic SystemChec$ system for lea$s %

Replenish system

Coat all unpainted hydraulic pipe0or$ ith preser)ati)e ompound

&ircraft ,-terior

/ash aircraft

Coat all unpainted metal surfaces ith preser)ati)e compound

&ircraft Interior

Remo)e passenger seats and carpets for ay storage

Remo)e; ser)ice and store all galley portale e7uipment

Remo)e; chec$ and store indshield iper arms complete ithlades

Remo)e rain repellent canisters

,lectrical@,lectronic System

Remo)e and ser)ice atteries

Remo)e for ay ser)ice; all rac$ mounted electronic e7uipment

&pply poer to and function installed electronic e7uipment %

If the aircraft is to e stored outside; additional par$ing procedures ill enecessary to pre)ent ingress of moisture. It is also necessary to pre)ent accessof insects; small animals and irds. (arious lan$s and co)ers ill minimisecontamination of the aircraft.

&fter the storage period all of the co)ers; lan$s and preser)ati)e compounds illneed to e remo)ed. &ll of the systems ill need to e restored to their originalcondition prior to aircraft use. &nother set of procedures ill e folloed; similar

to the ones detailed ao)e.



!." REFUELLING DEFUELLING

!.".1REFUELLING AIRCRAFT

/hen re0fuelling aircraft; care should e ta$en; particularly ith an unfamiliaraircraft; to ascertain that the correct procedures are oser)ed. The maintenancemanual should e consulted so the position and capacities of the fuel tan$s is$non and also the type of fuel; position of the refuelling point>s? and refuellingmethod is $non. There are to general refuelling methodsJ

• G/+*t- o/ oe/>=*n0 0 This is essentially the same method as used torefuel your car; a similar type of refuelling hose eing used. &s the namesuggests; the filler points are generally on the top of the tan$ and the tan$ isopen hen fuelling is carried out.

• P/ess/e Re@e,,*n0 0 In this method fuel may e pumped into the aircraft)ia a pressure refuelling coupling at )ery high rates. The refuelling pressuremay e up to p.s.i. and the refuel rate may e in the order of 1; gallonsper minute. The aircraft may also e de0fuelled )ia the same coupling yapplying suction to the hose. 8a-imum de0fuel pressure is normally in theregion of 011 p.s.i.

!.".2REFUELLING SAFETY PRECAUTIONS

Particular care must e ta$en hen fuelling aircraft so that the operation may ecarried out as safely as possile. The use of the term fuelling can include othrefuelling or de0fuelling. Pay particular attention to the folloing pointsJ

• /hene)er possile aircraft should e fuelled in the open; and not in a hangar.This ill minimise the fire ris$ due to high concentrations of inflammale)apours.

• +ire appliances should e readily a)ailale hen all fuelling operations areta$ing place. Caron dio-ide or foam e-tinguishers are recommended; ut ifany increased fire ris$ is anticipated; fire0fighting )ehicles should e standingy. There is a danger area around an aircraft eing fuelled hich e-tends aspecified distance from the fuelling point. 6o sources of ignition or spar$sshould e ithin this danger area and no electrical poer should e sitchedon or off during the operation.

• It is )ital that the correct type and grade of fuel e used for the fuellingoperation. #se of a turine fuel in a piston aircraft ill certainly cause anengine failure; possily at a crucial flight stage. The correct type and grade offuel should alays e stated in the maintenance manual and mar$edad<acent to the filler point>s?.

• Care should also e e-ercised to a)oid contamination of the fuel system ith

ater or other sources of contamination. The fuel supply should e regularlychec$ed for ater contamination and a sample of fuel drained off afterrefuelling so that a ater chec$ may e carried out. It ill sometimes enecessary to filter the fuel during o)er0ing refuelling; particularly in dustyclimates.

NoteJ Piston aircraft fuel tan$s are est $ept full; therey minimising theformation of condensation in the fuel tan$s.

• "onding of the fuel system is )ital during fuelling operations as staticelectricity may e generated as fuel flos through the refuelling hose. Thismay lead to potential differences at ad<acent metal parts of the structure andresult in a spar$ that could cause a fire or e-plosion. To minimise this ris$J

i. The aircraft should e earthed.



ii. The refuelling tan$er should e earthed.

iii. The refuel hose no==le should e onded to the refuel point.

NoteJ Points i 0 iii should all e done efore fuelling operations commence.

!.".3CHECKING FUEL CONTENTS

This is normally carried out using the aircraft fuel gauges; hich may ecalirated in gallons >Imperial or #S?; pounds or $ilograms. If a doule chec$ is

re7uired; or no fuel gauge is fitted; the contents may e ascertained on theground y using dip stic$s fitted into the top of the tan$s or y drip0 stic$s or dropstic$s hich are fitted in the ottom of some aircraft tan$s. The aircraft fuelgauges ill normally e positioned in the flight dec$; ut they may sometimes eduplicated at a fuelling panel ad<acent to the pressure refuel coupling.

'e+s/e6ent o@ Fe, - =e*0:t. The specific gra)ity >S.G.? of fuel ill )aryith temperature and so the eight of a certain 7uantity of fuel ill also )ary. +ore-ample; ten gallons of fuel ith an S.G. of .' ill ha)e a eight of ' lf. andten gallons of fuel S.G. .%' ill eigh %' lf. It is crucial for alance purposesthat the eight of fuel is $non and so modern gauges may e calirated in unitsof eight rather than in gallons. /hen fuelling aircraft; it is essential that theengineer is aare of the S.G. of the fuel so that the necessary eight calculationmay e carried out. The cre may as$ for a fuel 7uantity in pounds or $ilogramsand the fuel oser ill e deli)ering fuel in gallons.

!.".4TYPICAL AIRCRAFT FUELLING INFOR'ATION ;#AE 14"<

!.".4.1 Gene/+,

+uel is contained in three integral fuel tan$s; one in each ing and one in thefuselage centre section. & refuel@defuel station situated in the underside of theright ing leading edge; consists of a standard fuel coupling; an off load )al)e fordefuelling and transfer eteen tan$s; and a refuel control panel.

!.".4.2 Re@e,,*n0

Pressure refuelling is go)erned from the control panelK automatically y using theload pre0select; or manually y use of the tan$ refuelling )al)e o)erride sitches.In the e)ent of refuel cut0off failure the system is )ented to atmosphere )ia a6&C& duct located in each ing tip.)ering gra)ity refuelling points are pro)ided for each tan$.8agnetic fuel le)el indicators enale direct tan$ fuel le)el reading; to e ta$enfrom the ing tan$s only.

!.".4.3 De@e,,*n0

Selection of the off load )al)e to the open position connect; the main fuel feedline to the refuel gallery. +uel is then off loaded y selection of the appropriatecommon feed and cross0feed )al)es; and use of the fuel feed pumps. The centretan$ is offloaded y selecting fuel transfer to the ings ith the rele)ant ing fuelpumps selected 6.

!.".4.4 Fe, t/+ns@e/

Selection of the offload )al)e to the open position enales fuel to e transferredeteen tan$s y use of the appropriate common feed; refuel and crossfeed)al)es; and operation of the fuel feed pumps.

Selection of the TR&6S+,R sitch to either &#T or P,6; ill allo fuel to etransferred from the centre tan$ to the ing tan$s. & s7uat sitch inhiits the useof &#T TR&6S+,R on the ground.



!.".4.5 Fe,s +n +*t*es > A77/oe s7e*@*+t*ons

A77/oe @e,s

The fuels shall meet these specifications or any direct e7ui)alent.

KEROSENE FUELS

#/*t*s: A6e/*+n C+n+*+n IATA

:.,ng.R.:.24'2

:.,ng.R.:.24*4 &ST8 :1! Aet &1

C&6 203.2308'1 Eerosene Type

:.,ng.R.:.24*' C&6203.2308'1

A*t*es



The folloing additi)es are suitale for the system. They may e used singly or incomination; at the appro)ed concentrations.

&6Tl0CRRSI6 :.,ng.R.:.24!1 and &P524!1

&6TI0ICI6G &6: "lCl:&5 :.,ng.R.:.241 and 8l50T02%!'!

"lCl:&5 "I"R A+

&6TI0ST&TIC S9,55 &S&.3

:#P6T ST&:IS 4

!.".4." Us+,e @e, +7+*t*es

Imp. Gal. #S gal. litres 5 $g

/ing 5eft 11 121* 4!14 '12 3!'3

Centre !!1 2 44 1**!

/ing Right 11 121* 4!14 '12 3!'3

Total 2' 3** 11%2' 2!4 *3!2

NOTE8

1. These 7uantities refer to an aircraft fuelled to o)erride cut0off. /hen gra)ityfilled; the 7uantity in each ing tan$ reduces to 1 Imp gal. >12% #S gal.;4!* litres; '4 l; 3!4% $g.? ut the centre tan$ 7uantity remains the same.

2. The ao)e mass )alues of capacity are deri)ed from the )olumetric capacityassuming a Specific Gra)ity of .'. +or other )alues of SG correct the ao)emass )alues as follos here SG refers to the actual )alue for the fuelloaded into the aircraftJ

&ctual mass O SG - mass at .' SG@.'

!.".4.! L*6*t+t*ons

8a-imum refuel pressure J p.s.i. >3W4 ar?.

8a-imum defuel suction 11 p.s.i. >0.%! ar?.

8a-imum refuel rate is shon in the folloing taleJ

Imp.Gal@min #S gal@min 5itres@min 5@min Eg@min

Indi)idual /ing 12 144 4 *! 43

Centre tan$ ! %2 2%3 4' 21'

"oth /ings 22 2% 123 1' '1!

&ll tan$s 2% 33 12 22 **'

:o not refuel the centre tan$ unless the re7uired load e-ceeds the capacity of theing tan$s.

There are no tan$ imalance limitations during normal refuel or defuel operations.

+or refuel@defuel limitations ith the aircraft on <ac$s; refer to %00.



!.".4.$ Re@e,,*nBe@e,,*n0

WARNING8

1. ,6S#R, 5&6:I6G G,&R GR#6: 5CEI6G PI6S &6: C9CES &R,I6 PSITI6.

2. 6 S8EI6G R 6&E,: +5&8, /IT9I6 3 +,,T >*.14 8,TR,S?.

3. ",+R, C66,CTI6G T&6E,R 9S, T &IRCR&+T; 8&E, C,RT&I6T9&T &IRCR&+T &6: T&6E,R &R, C66,CT,: T &6 &PPR(,:GR#6: &6: T9&T T9, T&6E,R IS "6:,: T T9, &IRCR&+T.

4. I6 T9, ,(,6T + +#,5 SPI55&G, R +IR,; STP R,+#555I6G; S9#T:/6 R,+#,5 +&CI5ITB &6: ,5,CTRIC&5 P/,R; &6: P,R&T,T9, &P# C#T0++ SIT#&T,: &T T9, R,+#,5 C6TR5 P&6,5.

C&#TI6 J

1. #S, 65B &PPR(,: +#,5S.

2. 8&E, C,RT& 6 T9&T &:,Q#&T, +IR, +IG9TI6G +&CI5ITI,S &R, &(&I5&"5,.

3. C8P5B /IT9 5C&5 S&+,TB R,G#5&TI6S.

4. ",+R, PR,SS#R, R,+#,55I6G R :,+#,55I6G; ,6S#R, T9&T"5&6ES 9&(, ",,6 R,8(,: +R8 6&C& :#CTS &6 T9, (,6TPIP,S I6 T9, S#RG, T&6ES.

!.".4.& EB*76ent +n 6+te/*+,s

9C1392'0 /ater drain tool

Referenced Procedure

1201024 Ser)icing electrical poer

!.".4.1) P/e7+/e to /e@e,

1. 8a$e certain aircraft attery is connected.

2. 8a$e certain cross0feed )al)e is S9#T and all feed pumps are sitched++. 6T,J If necessary; only the left inner feed pump should e leftrunning for &P# operation.

3. In)estigate any contamination of the drained sample >T9,R T9&6/&T,R?. :rain all ater from tan$s; using ater drain tool.

4. pen refuel control panel door.

!.".4.11 P/e>/e@e, s-ste6 test

1. &t the refuel control panel chec$ off load )al)e is shut >le)er hori=ontal?; andthat ith 8&ST,R sitch ++; refuelling (&5(, position indicators shocross0hatch.

2. Turn 5&: PR,S,5,CT cloc$ise to ma-imum.

3. Select 8&ST,R sitch 6. Chec$ that (&5(, position indicators go toS9#T; and fuel 7uantity indicators sho correct e-isting fuel state.

4. Set 5,+T; C,6TR, and RIG9T tan$ refuel sitches to PR,0S,5,CT andchec$ that all three (&5(, position indicators go to P,6.

. Turn 5&: PR,S,5,CT counter0cloc$ise to =ero and chec$ that allthree (&5(, position indicators go to S9#T. 6T,J If the tan$ contents areat or elo unusale fuel0le)el >the le)el at hich the gauges and pre0selectare set at =ero? then the )al)es ill not shut.

!. Set all refuel )al)e sitches to (,RRI:, and chec$ that all three(&5(, position indicators go to P,6. Set sitches to S9#T and chec$that (&5(, indicators go to S9#T.



!.".4.12 P/ess/e /e@e,

1. "ond refuelling tan$er to aircraft onding point in right0hand main landinggear ay.

2. Position tan$er hose coupling; and ond hose to aircraft. Remo)e cap fromaircraft refuel coupling and connect refuelling hose.

3. Set all three refuel )al)e sitches to PR,0S,5,CT and ad<ust 5&: PR,0S,5,CT to re7uired load.

4. Chec$ that (&5(, position indicators sho P,6 for all tan$s due torecei)e fuel.

6T,J If load selected does not re7uire fuel in the centre tan$; the C,6TR,indicator ill sho S9#T.

%. Start refuelling. +lo ill stop automatically at pre0selected load.



'. +or asolute ma-imum fuel load; set )al)e sitches to PR,0S,5,CT andad<ust 5&: PR,0S,5,CT to its ma-imum; continue refuelling to pre0selectcut0off. Set )al)e sitches to o)erride; chec$ )al)e indicators sho P,6;continue refuelling until high le)el tan$ sitches operate and fuel flo stops.Chec$ that tan$ +#55 indicators come on.

*. Chec$ all (&5(, indicators sho S9#T; and that fuel 7uantity indicatorssho re7uired load.

1. &t flight dec$ centre instrument panel; chec$ fuel 7uantity indicators arereading correct load.

11. Set refuel sitches to S9#T and 8&ST,R sitch to ++.

12. :isconnect refuel hose anding and uncouple hose from aircraft. :isconnecttan$er onding.

13. Install lan$ing cap to aircraft coupling. Close and secure refuel panel door.

!.".4.13 Unse/*e+*,*t- o@ /e@e, +,e +t+to/

In the e)ent of an actuator failure; the refuel )al)e can e operated manually y ale)er ehind the actuator; accessile after remo)ing panel !21&" or !21"".

"efore using this method a signal must e arranged so that the )al)e can e shut

on instruction from an operator monitoring tan$ contents.The associated tan$ refuel (&5(, indicator must e ser)iceale during thismanual operation.

!.".4.14 Oe/=*n0 /e@e,

NOTE J

• 5imitations specified in para.4. are applicale for o)er ing refuelling.

• +or loads other than full; ings must e filled first and then remainder incentre tan$.

1. :rain all ater from tan$s using ater drain tool. C&#TI6 J I6(,STIG&T, &6B C6Tl8l6&TI6 + T9, :R&I6,: S&8P5, >T9,R T9&6/&T,R?.

2. pen refuel panel and select 8&ST,R sitch 6. Chec$ fuel contents.

3. "ond refuelling tan$er to aircraft onding point in right0hand main landinggear ay.

4. "ond refuelling hose no==le to aircraft.

. Remo)e fuel tan$ cap y raising handle and turning counter0cloc$ise ToP,6.

!. Insert no==le and refuel to re7uired le)el. Chec$ correct load y use of tan$

contents indicators on refuel panel.

%. Remo)e no==le and install tan$ cap ith arro >+/:? pointing forard.Rotate handle cloc$ise to register ith C5S,.

'. 5oc$ filler cap y pushing handle don to lie flush in its recess.

*. :isconnect no==le onding;

1. :isconnect onding from tan$er.

11. &t flight dec$ centre instrument panel; chec$ fuel 7uantity indicators shocorrect fuel load.

12. &t fuel control panel; select 8&ST,R sitch ++. Close and secure controlpanel door.



!.".4.15 De@e, ;o@@,o+<

6T, J Refer to limitations; para.4.

1. ,nergise aircraft usars >Ref.1201024?.

2. pen refuel control panel door.

3. "ond defuel tan$er to aircraft onding point in right0hand main landing gearay.

4. Position tan$er hose coupling and ond to aircraft. Remo)e cap from refuelcoupling; connect tan$er hose.

. Select off load )al)e to open y pulling le)er don to )ertical position.

!. &t flight dec$ o)erhead panel >+#,5 section?

&. Select C886 +,,: and 0+,,: )al)es P,6.

". Select rele)ant fuel feed pumps to 6. +uel ill no off load totan$er. &pply tan$er suction.

C. T defuel centre tan$; select tan$ TR&6S+,R sitch P,6. +uel illtransfer to the ing tan$s as they are offloaded.

14. /hen tan$s are defuelled to re7uired le)el; shut don tan$er and select

offload )al)e closed y pushing up le)er to hori=ontal.6T, J & aul$ pre)ents the fuel control panel access door closing hen the offload )al)e is selected open.

1. &t o)erhead panel; select pumps to ++; 0+,,: and C886 +,,:to S9#T; and centre tan$ TR&6S+,R to S9#T.

1!. :isconnect tan$er hose onding; and uncouple hose.

1%. +it lan$ing cap to aircraft fuel coupling. Close and secure refuel controlpanel door.

1'. :isconnect tan$er onding from aircraft.

1*. &t flight dec$ centre instrument panel; chec$ fuel tan$ indicators sho correct

load.2. :e0energi=e aircraft usars >Ref.1201024?.

!.".4.1" T+n ontents :e s*n0 6+0net* *n*+to/s

8agnetic fuel le)el indicators >85I? are an appro-imate measure of fuel contentin ing tan$s and are intended for use if capacitance contents system is suspect.

+our manually operated magnetic proes mounted to in each ing tan$ enaledirect fuel le)el readings to e ta$en. The proes are graduated and readingsta$en are related to caliration tales to calculate tan$ fuel contents.

The tales are related to aircraft attitude as read from attitude indicator situated

in roof of right0hand main landing gear ay.Procedure

1. tain fuel sample and chec$ specific gra)ity.

2. ,nergi=e aircraft usars >Ref.1201024?.

3. Chec$ feed tan$s are full 0 fuel lo le)el arnings off. If lo le)el arningsare on; sitch on inner fuel pumps >or standy pumps? and ait for arningsto go off.

4. Read aircraft indicator grid reference and determine actual aircraft attitude.

. To read 85I; use a scredri)er to press proe in and rotate through *degrees.



!. /ithdra proe sloly until it loc$s on float. Aer$ don to rea$ magneticlin$. Push proe up gently; resting on finger or thum; until it <umps up andloc$s to magnet.

%. Ta$e reading using underside of ing s$in as reading le)el.

'. Push proe up and use a scredri)er to push fully in and secure y rotatingthrough * degrees.

*. n certain aircraft it is necessary to con)ert 85I reading to $gs usingcaliration tale applicale to indicated aircraft attitude and specific 85I

used.1. n other aircraft con)ert 85I reading to Is using caliration tale applicale

to indicated aircraft attitude and specific 85I used.

11. n &55 aircraft sitch off appropriate fuel pumps and de0energi=e aircraftusars >1201024?.

!.".4.1! C+,*/+t*on t+,es

n aircraft 203;03;3%;4042; 4!04*

The tan$ contents figures in the tales are for one ing only.

The tales are calirated for a fueI specific gra)ity >s.g.? of .'. To correct the fuel7uantity for different specific gra)ities; di)ide the indicated 7uantity y .' andmultiply y the actual specific gra)ity of the fuel.



/hen using the tales it is permissile to interpolate for intermediate 85Ireadings and aircraft attitudes. Pro)iding this is done accurately and the fuel s.g.correction is applied; then the fuel 7uantity figure otained ill e ithin X@0 $gs of the actual fuel contents of the ing.

n aircraft 203;03; 3%; 4042; 4!04*



!.! GROUND SUPPLIES

!.!.1ELECTRICAL

Ground electrical supplies are often necessary for engine starting or to permitoperation of aircraft e7uipment on the ground hen the engine dri)en generatoris not running; thus minimising the load on the aircraft internal atteries.

8any small aircraft ha)e direct current >:C? electrical systems and althoughalternating current may e pro)ided for the operation of certain e7uipment; it isnot usual for the aircraft to ha)e pro)ision for the connection of &C poer. Thee-ternal poer soc$et is usually for the connection of a :C poer supply. nlarger aircraft; there is usually pro)ision for connection of oth &C and :C poer.

!.!.1.1 'et:os o@ S77,-*n0 E,et/*+, Po=e/

• T/o,,e- A6,+to/s 0 >Trolley &cc.? This is the most commonly usedtype of unit for small aircraft. It consists of a trolley in hich are installed aset of atteries >usually 12(olt? and a lead to connect to the :C soc$et on the

aircraft. The atteries are connected in parallel or series@parallel so that theymay supply the re7uired )oltage to the aircraft. The unit may also ee7uipped ith a master sitch so that the poer can e sitched to theaircraft; and possily a meter and indicating light to sho hen poer is 6.

• En0*ne D/*en Gene/+to/s. 0 These may e diesel; petrol or electric motorscoupled to a rushless re)ol)ing field generator; and a poer unit pro)idedith full controls and instrumentation. Typical poer outputs may eJ

• A,te/n+t*n0 C//ent

% $(& 2( 49= 3 Phase &C poer

• D*/et C//ent

2'. ( ' amps continuous or 2; amps intermittent

o/ 112 ( 3 amps continuous or 1; amps for 3 sec.

• '+*ns S77,- t:/o0: T/+ns@o/6e/s o/ Ret*@*e/s. 0 These are oftenused in hangars; here the hangar mains are connected to transformer unitsto supply &C; or to moile rectifier units to supply :C poer. ,ach unit oulde e7uipped ith a control panel so that the poer can e sitched throughto the aircraft.

• A*,*+/- Po=e/ Un*ts >&u-. #nit? 0 Some aircraft are e7uipped ith aninternal au-iliary poer unit; hich consists of a gas turine engine dri)ing an

&C generator hich may e used as a source of emergency poer; or asource of ground poer.

!.!.1.2 Connet*on o@ DC E,et/* G/on Po=e/

It is essential that personnel ho are re7uired to use ground poer units aretrained and fully familiar ith their operation and associated safety precautions.The folloing practices ould e typical for a small aircraft ith a :C supplyJ

1. Chec$ the )oltage and polarity of the ground supply.

2. Chec$ that the e-ternal poer plug; and soc$et are clean; dry andundamaged.

3. Chec$ that ot: the e-ternal supply and the attery master sitch are o@@and connect the e-ternal supply; ensuring the plug is fully home in thesoc$et.



4. Sitch on the e-ternal supply and the attery master sitch and carry out theser)icing operations for hich the e-ternal poer as re7uired.

. To disconnect the e-ternal supply; sitch off the attery master sitch;sitch off the e-ternal supply; disconnect the poer plug; and if the aircraftelectrical system is to e used >e.g. after engine starting?; sitch the atterymaster sitch on again.

!.!.1.3 Connet*on o@ G/on Po=e/ to L+/0e A*//+@t

8ost large aircraft are fitted ith multi0pin soc$ets y hich e-ternal :C and &Cpoer may e supplied to the aircraft. The e-ternal poer set is capale ofsupplying :C poer at )arious )oltages and &C poer at a specific )oltage;fre7uency and phase rotation. &ircraft electrical systems )ary consideraly andthe chec$s necessary efore and after connection of electrical poer ill )aryeteen aircraft. The folloing procedure is applicale in most casesJ

1. Chec$ that the e-ternal supply is compatile ith the aircraft system >i.e. ithas the same )oltage; fre7uency and phase rotation as the aircraft system?;and is sitched off.

2. Chec$ that the e-ternal plug and soc$et are clean; dry and undamaged.

3. Connect the e-ternal plug@soc$et; ensuring that it is fully mated and secure;

and sitch on the e-ternal poer supply.4. Chec$ the )oltage and fre7uency of the e-ternal supply on the aircraft

electrical system instruments; and perform the operations specified in therele)ant 8aintenance 8anual to engage the e-ternal supply ith the aircraftsystem.

. To disconnect the electrical supply; sitch off the supply at the poer sourceand remo)e the poer plug from the aircraft soc$et.

!.!.2HYDRAULIC

!.!.3PNEU'ATIC

!.!.4EFFECTS OF EN(IRON'ENTAL CONDITIONS ON AIRCRAFTHANDLING OPERATION



$. INSPECTION REPAIR TECHNI%UES

$.1 CORROSION ASSESS'ENT REPROTECTION

$.1.1PRE(ENTATI(E 'AINTENANCE

:ue to the high cost of modern aircraft; operators are e-pecting them to lastmuch longer than perhaps e)en the manufacturer anticipated. &s a result themanufacturers ha)e ta$en more care in the design of the aircraft to impro)e thecorrosion resistance of aircraft. This impro)ement includes the use of nematerials and impro)ed surface treatments and protecti)e finishes. The use ofpre)entati)e maintenance has also een emphasised more than it aspre)iously. Pre)entati)e maintenance should include the folloing measuresJ

• &de7uate and regular cleaning of the aircraft

• Periodic lurication; >often after the cleaning?

• Regular and detailed inspection for corrosion and failure of protecti)etreatments.

• Prompt treatment of corrosion and touch up of damaged paint

• Eeeping drain holes clear

• :raining of fuel cell sumps

• :aily ipe don of most critical areas

• Sealing of aircraft during foul eather and )entilation on sunny days

• #se of protecti)e co)ers and lan$s

$.1.2CORROSION RE'O(AL

General the corrosion remo)al treatment includes the folloing main stepsJ1. Cleaning and remo)al of protecti)e coat on the corroded area

2. Remo)e as much of the corrosion products as possile

3. 6eutralise the remaining residue

4. Chec$ if damage is ithin limits

. Restore protecti)e surface films

!. &pply temporary or permanent coatings or paint finishes.

C,e+n*n0 +n P+*nt Re6o+,. If corrosi)e attac$ has not progressed eyondthe point re7uiring structural repair; it is essential that the complete suspect areae cleaned of all grease; dirt or preser)ati)es. This ill aid in determining the

e-tent of corrosi)e spread. The selection of cleaning materials ill depend onthe type of matter to e remo)ed. :ry cleaning sol)ent >trichloethane 0Genclean? may e used for oil; grease or soft compounds. 9ea)y duty remo)alof thic$ or dried compounds may need sol)ent emulsion type cleaners.

General purpose; ater remo)ale stripper is recommended for most paintstripping. &de7uate )entilation should e pro)ided and synthetic ruer surfacessuch as tyres; faric and acrylics should e protected. Care should also e ta$ento ensure that the correct specification paint remo)er is used. If the rongremo)er is used; certain materials may e damaged. Redu- "onded structuresare particularly susceptile to damage. Remo)er may also soften pressurisationsealant and plastic materials such as perspe-. If the remo)er is sol)ent ased;the )apour from the sol)ent ill cause damage. Ruer glo)es; acid repellentaprons and goggles should e orn y personnel carrying out paint remo)aloperations.



The folloing is a general paint stripping procedureJ

1. "rush area ith stripper to a depth of 1@32 to 1@1! inch. ,nsure rush is onlyused for paint stripping.

2. &llo stripper to remain on surface long enough for paint to rin$le. Thismay ta$e 1 min. to se)eral hours.

3. Re0apply the stripper to areas that ha)e not een stripped. 6on0 metallicscrapers may e used.

4. Remo)e the loosened paint and residual stripper y ashing and scruing

surface ith ater and a room or rush. /ater spray may assist; or steamcleaning e7uipment.

$.1.3CORROSION OF FERROUS 'ETALS

&tmospheric o-idation of iron or steel surfaces causes ferrous o-ide rust to edeposited. Some metal o-ides protect the underlying ase metal; ut rustpromotes additional attac$ y attracting moisture and must e remo)ed. Rustshos on olt heads; nuts or any un0protected hardare. ItFs presence is notimmediately dangerous; ut it ill indicate a need for maintenance and possilecorrosi)e attac$ on more critical areas. The most practical means of controllingthe corrosion of steel is the complete remo)al of corrosion products y

mechanical means. &rasi)e papers; poer uffers; ire rushes and steel oolare all acceptale methods of remo)ing rust on lightly stressed areas. Residualrust usually remains in pits and cre)ices. Some phosphoric acid solutions maye used to neutralise o-idation and con)ert acti)e rust to phosphates; ut theyare not particularly effecti)e on installed components.

$.1.4HIGHLY STRESSED STEEL CO'PONENTS

Corrosion on these components may e dangerous and should e remo)edcarefully ith mild arasi)e papers or fine uffing compounds. Care should eta$en not to o)erheat parts during remo)al. Protecti)e finishes should e appliedimmediately.

$.1.5PRE(ENTION OF CORROSION

Protection against corrosion can e gi)en in a numer of ays. Some of theprinciples in)ol)ed are riefly summarised eloJ

• C:o*e o@ 'et+,s. Certain metals ha)e a high natural resistance tocorrosion. 6ole metals such as Gold; Sil)er and Platinum ha)e a lo affinityto o-ygen and therefore ill not tend to o-idise readily. Some metals such asStainless Steel and pure aluminium oe their properties to a thin film ofo-ides hich protects against further attac$.

• P+ss**t-. In certain conditions metals and alloys commence to corrode and

the initial products of corrosion form protecti)e films hich limit further attac$.6atural passi)ity is sufficient protection for pure aluminium and stainlesssteel; ut passi)ity can to e produced artificially for aluminium alloys>&nodising?.

• S/@+e F*n*s:. Corrosion resistance can often e greatly increased ycareful attention to surface finish. 8any engine parts are highly polished; utotherise only protected y clear )arnish.



• C:e6*+, In:**t*on. ne of the most idely used methods of protection isto treat the metal ith chemicals hich inhiit corrosion and so artificiallyintroduce a form of passi)ity. These methods are often used as first aidtreatment of corroded aircraft parts. (arious methods are used; dependingon the materials to e protected; ut &lochrom or &lodyne is often used foraluminium alloys. The Phosphating process and Aenolite may erecommended for steel and the chromate process for magnesium alloys.

• S+/*@**+, P/otet*on. /hen to metals of different electric potential are in

close contact; the elements of a )oltaic cell may e estalished. The metalhich is anodic to the other ill e attac$ed y corrosion. This principle maye delierately e applied to protect constructional materials. +or e-ample;oth Cadmium and &luminium are anodic to steel and ill corrode inpreference to the steel. &t the same time they corrode at a much sloer ratethan steel and ill gi)e protection for a )ery long time. +or this reason steelcomponents; particularly fasteners are usually cadmium plated.

• 'e:+n*+, P/otet*on. Corrosion can e pre)ented y e-cluding ater;o-ygen and corrosi)e chemicals from the surface of the metal. This methodis the asis of most organic coatings such as )arnishes; paints and enamels;hich are applied on top of priming coats. To e effecti)e the coats shoulde atertight. ther methods of mechanical protection include metalliccoatings applied y dipping; spraying or electro0deposition.

$.1."ALU'INIU' AND ALU'INIU' ALLOYS

Corrosion attac$ on aluminium surfaces gi)e o)ious indication; since theproducts are hite and )oluminous. ,)en in its early stages aluminium corrosionis e)ident as general etching; pitting or roughness. &luminium alloys form asmooth surface o-idation hich pro)ides a hard shell hich may form a arrier tocorrosi)e elements. This must not e confused ith the more serious forms ofcorrosion.

General surface attac$ penetrates sloly; ut is speeded up in the presence of

dissol)ed salts. Considerale attac$ can ta$e place efore serious loss ofstrength occurs. Three forms of attac$ are particularly serious.

• Penetrating pit type corrosion through alls of tuing.

• Stress corrosion crac$ing under sustained stress.

• Intergranular attac$ characteristic of certain improperly heat treated. 9ighstrength &l. &lloys >% series &l; [inc alloys?. This can de)elop intoserious e-foliation corrosion forming layers of fla$ing metal.

Treatment in)ol)es replacement of the component or mechanical @ chemicalremo)al of as much of the corrosion products as possile and the inhiition ofresidual materials y chemical means. This should e folloed y restoration of

permanent surface coatings.

$.1.!ALCLAD

Pure aluminium has more corrosion resistance than the stronger aluminiumalloys. To ta$e ad)antage of this; a thin sheet of pure aluminium is laminated tooth sides of the aluminium alloy. The alclad surfaces offer good protection andcan e maintained in a polished condition. Care should e ta$en not to remo)etoo much of the aluminium layer y mechanical methods as the core may ee-posed.

$.1.$TYPICAL PAINTED CORROSION TREAT'ENT SE%UENCE

1. Remo)e oil and surface dirt ith the appropriate sol)ent.

2. Paint strip the area to e treated.



3. Remo)e the products of corrosion using scrapers >ta$ing care not to remo)emetal? or arasi)e paper >et and dry? or ire ool.

4. 6eutralise any residual ith the appropriate chemical cleaner and then ashoff ith ater. 8any chemical cleaners e-ist. :eo-idine 22 is a phosphoricacid cleaner used on &luminium &lloys. It should not e used on 8agnesium &lloys. Chromic acid is recommended for 8agnesium &lloys.

. &pply protecti)e treatment. This may e &lochrom 12 or &lodine for &luminium &lloys or Chromic &cid treatment for 8agnesium &lloys.

!. Restore surface finish.

$.1.&PER'ANENT ANTI>CORROSION TREAT'ENTS

These are intended to remain intact throughout the life of the component; asdistinct from coatings that may e reneed as a routine ser)icing operation. Theygi)e etter adhesion for paint and most resist corrosi)e attac$ etter than themetal to hich they are applied.

E,et/o>P,+t*n0. +alls into to categoriesJ

• Coatings less nole than the asic metal. The coating is anodic to the asemetal and so if ase metal is e-posed; the coating ill corrode in preference

to the ase metal. Commonly called sacrificial protection. ,-amples areCadmium plating or =inc on steel.

• Coatings more nole e.g. nic$el or chromium on steel. These noler metalsdo not corrode easily in air or ater and are resistant to acid attac$. If theasic metal is e-posed; it ill corrode locally y electrolytic action. The attac$may result in pitting corrosion of the ase metal or the corrosion may spreadeneath the coating.

S7/+-e 'et+, Co+t*n0s. 8ost metal coatings can e applied y spraying; utonly aluminium and =inc are used on aircraft. &luminium sprayed on steel isfre7uently used for high temperature areas. The process >&lumini=ing? producesa film aout .4M hich pre)ents o-idation of the underlying metal. & supply of

o-ygen and acetylene is piped to a spray gun and ignited as in a elding torch. & ire of aluminium is fed through the spray gun; melted y the flame and thronagainst the surface eing metallised y the compressed air.

C,+*n0. 9ot rolling of pure aluminium onto duralumin produces &lclad that hasgood corrosion resistance and the high strength of the alloy. If the claddingecomes damaged; e-posing the core; the material ill corrode easily. 8ostaircraft s$in is made from &lclad.

S/@+e Cone/s*on Co+t*n0s >&rtificial Passi)ation?. These are produced ychemical action. The treatment changes the immediate surface layer into a filmof metal o-ide hich has etter corrosion resistance than the metal. &mongthose idely used on aircraft areJ

• The &nodising of &luminium &lloys y an electrolytic process hich thic$ensthe natural o-ide film on the aluminium. The film is hard; inert and may ecoloured.

• The chromating of 8agnesium &lloys to produce a ron to lac$ surface filmof chromates hich form a protecti)e layer.

• Passi)ation of =inc and cadmium y immersion in a chromate solution.

ther surface con)ersion coatings are produced for special purposes; notaly thephosphating of steel. There are numerous proprietary processes; each $non yitFs trade name e.g. Par$erising; /alterising.



$.1.1) ACID SPILLAGE

&cid spilled in aircraft can cause se)ere corrosion. &cids ill corrode mostmetals used in aircraft and ill destroy ood and most farics. &ircraft atteriesgi)e off acidic fumes and attery ays should e ell )entilated; surfaces in thearea should e treated ith anti0acid paint. The correct procedure to e ta$en inthe e)ent of a spillage is as follosJ

1. 8op up as much of the spilled acid using et rags; try not to spread the acid.

2. If possile; flood the area ith large 7uantities of clean ater

3. If flooding is not practical; neutralise the area ith the folloingJ 1\ yeight "icaronate of Soda ith ater.

4. /ash the area using this mi-ture and rinse ith cold ater.

. To chec$ if acid has een cleaned up; test the area using uni)ersal indicatingpaper >or litmus paper?.

!. :ry area completely and e-amine the area for signs of damaged paint orplated finish and signs of corrosion especially here the paint may ha)eeen damaged.

%. Restore damage as appropriate.

$.1.11 ALKALI SPILLAGEThis is most li$ely to occur from main aircraft 6ic$el0Iron atteries containingPotassium 9ydro-ide. "attery compartments should e painted ith anti0corrosi)e paint. Remo)al of the al$ali spillage is as follosJ

1. 8op up as much as possile ith a et rag.

2. Sa area ith the folloing mi-ture hich ill neutralise the al$ali andpassi)ate are metalJ \ y eight chromic acid in ater.

3. +lood area ith clean ater a)oiding electrical gear.

4. Chec$ area for neutralisation ith uni)ersal indicating paper or litmus paper.

. If o$ay; dry area and chec$ for corrosion and damaged paint etc.

$.1.12 'ERCURY SPILLAGE

Sources of mercury spillage are instruments; sitches and test e7uipment.8ercury can rapidly attac$ are light alloys causing inter0granular penetrationand emrittlement hich can start crac$s and accelerate crac$ propagation.Signs of mercury attac$ on aluminium alloys are greyish poder; his$ery grothor fu==y deposits. If mercury corrosion is found or suspected; assume inter0granular penetration has occurred and the structural strength is impaired. Themetal in that area should e remo)ed and the area repaired i.a.. manufacturersinstructions.

Re6o+, o@ 'e//- S7*,,+0e. ,nsure that to-ic )apour precautions are

oser)ed at all times during the folloing operationJ1. :o not mo)e aircraft after finding spillage. This may pre)ent spread.

21. Remo)e spillage carefully y one of the folloing methodsJ

:. Capillary rush method

,. 9ea)y duty )acuum cleaner ith collector trap

+. &dhesi)e tape pressed onto gloules ill pic$ them up

G. +oam collector pads

22. Try to remo)e e)idence of corrosion

23. The area should e further chec$ed using radiography to estalish that allgloules ha)e een remo)ed and to chec$ e-tent of corrosion damage.

24. ,-amine area for corrosion using a magnifier; any parts found contaminatedshould e remo)ed and replaced.



$.1.13 IDENTIFICATION OF 'ETALS

If the nature of a metal is un$non i.e. you donFt $no hat material it is; it mayoften e identified y itFs reaction or lac$ of reaction to )arious chemicals.

• A,6*n*6 +n A,,o-s. 5ight grey in colour; light in eight. 6ot affected y6itric acid; &cetic acid or &mmonia. &ttac$ed y 9ydrochloric acid Sulphuricacid and &l$alis.

2\ Caustic Soda solution forms a clear solution ith aluminium and a grey

or lac$ precipitate ith &luminium &lloy.• '+0nes*6 A,,o-s. 5ight in colour. 5ight in eight. &ttac$ed y saturated

Sulphuric acid solution.

• #/onJes >&luminium Phosphor?. Colour usually coppery or reddish. &ttac$ed y 6itric acid to form a solution; hich hen oiled produces ahite precipitate.

• Fe//os 'et+,s. Characteristic FSteelyF appearance in most cases; e-ceptCast Iron hich is lac$ or grey. 8ost steels are magnetic; e-cept austeniticsteels and some stainless steels.

9eating ferrous particles in near oiling nitric acid until chemical action ceases

producesJ

• & yello or light ron solution if the particles are caron steel.

• & dar$ ron solution if the particles are cast iron

Note. Stainless Steel ill not e attac$ed in this test



$.2 NON DESTRUCTI(E TESTING

$.2.1INTRODUCTION

The early detection of defects efore they ecome critical is )ital in aircraftengineering. These notes e-plain the asic principles of the most commonmethods used. 6on :estructi)e Testing >6:T? or 6on :estructi)e ,-amination>6:,? is a )aluale tool for detection of potential failure areas.

It is essential that the student is aare of the folloingJ

• The asic 6on :estructi)e Testing >6:T? methods a)ailale and principles ofeach method

• :ye Penetrant method in detail.

• The regulations concerning ho can carry out 6:T testing.

$.2.2#ASIC 'ETHODS

Refer to C&P !2 Section 4. Read this; as it contains all the information re7uiredy the C&&.

• O*, +n :+, 6et:o. This method has een superseded y the penetrantmethod; ut the C&& may still as$ if you are aare of it; particularly the"ristol 8odified method.

• Penet/+nt -e 6et:o. Bou must $no this in detail; particularly thereasons hy you might get poor results from this method and the differenttypes of penetrant. 9o many of you ha)e done a dye penetrant test ReadC&P !2 concerning the use of dye penetrant for testing for lea$s >includingthe test for pressurised )essels?.

• U,t/+>son* @,+= etet*on. "asic principles; hat types of defects @materials and ho ould normally carry out these tests.

• '+0net* @,+= etet*on. Types of defect@materials; asic principles;essential to de0magnetise after testing. :ifference eteen current flomethod and induction method.

• E- //ent. "asic principles; types of materials @ defects.

• R+*o,o0*+, e+6*n+t*on. "asic principles; hen; ho and safety aspects.

• (*s+, 6et:os. i.e. magnifying e7uipment and optical proes such asendoscope; oroscope or firescopes. See C&P !2.

$.2.3OPTICAL NDT 'ETHODS

(isual inspection is the oldest of the non0destructi)e methods of testing. It is a7uic$ and economical method of detecting )arious defects; especially crac$s;efore they can progress to failure.

This is the simplest of all methods and ill usually rely on good illumination on aclean surface. The most straightforard of these is a good torch used incon<unction ith the M8ar$ 1 ,yeallM. It is surprising ho easy it is to spot asmall defect if you loo$ properly. )ious aids ould e a mirror on a fle-ilestem and a 2. - 1 - magnifying glass.

O7t*+, A*s. 8any other )isual @ optical de)ices are in common use to aid

detection of defects; particularly in confined spaces. Some rely on mirrors orlenses; some on fire optic de)ices that can e connected to a still or )ideocamera to gi)e a photographic or a )ideo image.



• #o/eso7es. This is a precision optical instrument ith a uilt in light source.These range in length and diameter and design so that they may e used to)ie internal structures in a )ariety of applications such as inside turine andpiston enginesK internal structures of the ing etc.. They may; y the use oflenses; prisms and mirrors )ie forards; rearards or at any angle to theinstrument. They also ha)e ad<ustale focus of the eye piece to minimise eyestrain for the )ieer.

• F*/eso7e. These de)ices are similar to the orescope; ut rely on fire

optic cale rather than a rigid tue and lenses@mirrors. The image is )ieedthrough a unch of fire optic strands. The o<ect is illuminated y lighttransmitted through another unch of fire optic strands. These de)ices maye e-tremely thin and may e fle-ile so that they can e guided through theaircraft structure. The image may e )ieed through an eyepiece; or on a T(screen )ia a )ideo camera.

"orescopes and firescopes are most often used to inspect the inside of gasturine engines; ut can e used for many inspections such asK loose articlechec$s; fuel lea$s etc.

$.2.4DYE PENETRANT TESTING

$.2.4.1 O*, C:+, P/oesses

This is an old method similar in action to dye penetrant methods. ,ssentially thecomponent to e tested is cleaned y immersion in an acid pic$le ath or in paintremo)er. The cleaning solution is then cleaned off. The component is thenco)ered ith the oil solution either y immersion in hot oil or coated y cold oil;depending on the process. The surplus oil is then remo)ed and the componentcoated ith +rench Chal$ >)ery fine chal$ poder? that dras out the oil from thedefects. The main prolems ith this method are that the stained areas do notcontrast )ery ell ith the chal$.



$.2.4.2 #/*sto, 'o*@*e O*, C:+, 'et:o

This is the most ad)anced oil chal$ method and as such is the only one youare li$ely to e as$ed aout.

• Parts to e e-amined should e cleaned and then immersed in a solution of\ paraffin and \ spindle oil at %NC for a soa$ing period >one hour?.

• &fter immersion; allo the parts to stand to allo surplus oil to drain.

• Transfer to hot degreasing tan$ >%NC 0 'NC? containing Teepol \; Cresylic

acid \ and ater *\ for 3 to minutes.• Transfer to clean hot ater for 3 0 minutes and then drain.

• /hen dry; coat parts ith +rench Chal$ and then remo)e surplus chal$ ithair pressure at 2 0 3 psi.

• ,-amine for defects; indicated y a line of chal$.

$.2.5PENETRANT TESTING

Important points are as follos8

T-7e o@ De@et '+te/*+,s. Penetrant testing may e used to detect surfacedefects in any non0porous materials; including metals; plastics ceramics. It may

also e used to detect porosity in materials that should not e porous.

The asic principle of penetrant fla detection is that a li7uid dye is applied to thesurface of the material and it migrates into the crac$. ,-cess penetrant is thenremo)ed from the surface and a de)eloper applied. This de)eloper dras out thepenetrant dye and is suse7uently stained. The stained area indicates a defect.

Penetrants are a)ailale in many different forms. The most popular are termedcolour contrast for )ieing in natural light or fluorescent dyes for )ieing in ultra)iolet light. They may e applied y rushing; spraying or dipping. Somepenetrants are also a)ailale in a thi-otropic >gel; ut ecomes li7uid onapplication? form. 8ention should also e made of the post0emulsifier types ofpenetrant. &n emulsifier is a lending of etting agents hich allos e-cess

penetrant to e remo)ed ith ater. Some penetrants contain an emulsifier andith others; the emulsifier is applied as a separate stage. 8ost penetrant F+ieldEitFsF use an oil ased penetrant hich uses a sol)ent for cleaning instead ofater. The sol)ent is usually Trichloroethane ased.

#+s* P/oess. The dye penetrant process can e ro$en don intoJ

• Surface preparation and pre0cleaning

• &pplication of the penetrant

• Remo)al of e-cess penetrant

• &pplication of the de)eloper

• Inspection and recording defects

• Cleaning and restoration of surface finish

)iously if a defect is found; the fault ill ha)e to e rectified.

S/@+e P/e7+/+t*on. The surface of the material to e tested must ecompletely clean and free from dirt; paint surface treatments. Paint should eremo)ed using an appro)ed remo)er; ta$ing care not to apply remo)er to areaFshich might e damaged >Redu- onding on Concord rudder?. Ta$e care not todamage the material surface ith scrapers as this might appear as a defect. &fter paint remo)al; the surface should e ashed ith ater or cleaned ith anappro)ed sol)ent and then dried.



A77,*+t*on o@ Penet/+nt. The penetrant should e applied to the clean surface;using a spray; rush or y dipping. The penetrant should e left on the surfacefor the recommended contact time and $ept et. This time ill usually dependon the temperature and the si=e of the suspected defect. & time of 0 3minutes eing normally recommended. &t )ery lo temperatures; e-tra timeshould e alloed ecause the material >and the defect? ill contract and thepenetrant ill not e dran into the defect.

Re6o+, o@ Eess Penet/+nt. This is another area here incorrect proceduresill cause poor results. The o<ect of the e-ercise is to remo)e all of the surfacepenetrant ithout remo)ing any of the penetrant that is in the defect. In the past;operators ha)e een $non to spray penetrant remo)ers directly onto thesurface; thus ashing the penetrant out of the defect. The recommendedmethod ith sol)ent ases spray remo)ers is to remo)e the e-cess penetrantith a clean cloth and then apply the remo)er to a clean cloth and ipe thesurface ith the cloth. Repeat until clean.

A77,*+t*on o@ t:e Dee,o7e/ . The de)eloper consists of either a dry poder; ora poder suspended in a li7uid. The poder acts as a lotter; draing thepenetrant out of the defect. The aim is to produce an e)en co)erage of thecomponent; ithout gi)ing too thic$ a layer >this might completely lan$et thepenetrant?. The de)eloper is applied either y aerosol spray; puffer; electrostatic

spray gun or using a dust cainet. Time should e alloed so that the penetrantcan e dran out of the defect. The normal time is one half the penetrant contacttime.

Ins7et*on +n Reo/*n0 De@ets. Inspection for defects should e carriedout using good illumination. This ill e normal hite light for penetrant dyes;and ultra0)iolet >lac$? light for fluorescent penetrant >these eing mainly used indar$ areaFs and for fine crac$s?. :efects ill sho up as shon in the diagramelo. The rate of staining eing an indication of the idth and depth of thecrac$. Porosity may sho up as a large dotted area. It is important that thee-act position of the defect is recorded; ecause it might not e o)ious herethe defect is hen the component is cleaned.

Resto/e S/@+e F*n*s:. If there are no defects; the component should ecleaned and the surface finish restored. This may in)ol)e etch priming; paintingand possily restoration of anti0corrosi)e treatment. If the component is to echec$ed regularly; hoe)er; it may e permitted to apply a coating of protecti)eoil; grease or inhiiting fluid eteen inspections.

$.2."ULTRA SOUND TESTING

This method may e used to detect su0surface defects in all solid materials.

#ltra Sonic methods can also e used to measure the thic$ness of materialshen it is only possile to get access to one side of the component.



U,t/+ Son. This descries sound at a pitch too high to e detected y thehuman ear. The fre7uencies used in ultra0sonic testing are normally ithin therange E9= to 1 89=. The speed of sound through a particular material)aries and so a different fre7uency is used depending on the material. Thesound a)es used in ultra sonic testing are produced and detect y means of atransducer; i.e. a de)ice hich con)erts electrical energy to mechanical energyand )ice )ersa. & pie=o0electric crystal is made to )irate hen stimulated yelectrical energy from a pulse generator. This )iration causes ultra0sonic a)esto e transmitted through the material to hich the pie=o0electric transmitter is

applied. The a)es may e reflected ac$ from surfaces >or defects?; thereflected a)es are recei)ed y another pie=o0electric crystal con)erting thesound a)es into a signal; displayed on a screen.

#ltra0sonic a)es ill e transmitted through any li7uids or solids. &nydiscontinuity or interfaces present; particularly those ith air gaps ill causealmost complete reflection of the a)es. "ecause the a)es tra)el at a constantspeed; the time ta$en for the a)es to tra)el can e shon on a cathode ray tueas shon in the diagram.



The pre)ious diagram shos that the system may utilise a separate transmitterand recei)er or ha)e a comined transcei)er. If the depth of the component isuniform; a defect ill easily sho up y )ariations in the position of the reflectedpulse. Since the sound a)es ill e reflected at air interfaces a good acousticcontact is re7uired eteen the transmitting proe and the component. Thiscontact is impro)ed y the use of a li7uid >couplant? applied eteen the proeand the material. This couplant li7uid may e glycerine; silicon grease;petroleum <elly or a medium )iscosity oil.

$.2.!EDDY CURRENT TESTING

This method of e-amination may e used on electrically conducti)e materials andhas the ad)antage that )ery little preparation of the surface is re7uired and thecomponent may not need to e remo)ed. Small attery portale sets may eused in inaccessile parts of aircraft.

The asic principle is that a proe; consisting of a small coil supplied ith &Ccurrent is held in contact ith >or close pro-imity to? the component. Thealternating magnetic field itself produces an alternating magnetic field hichopposes and modifies the original field. In aircraft or$; eddy current testing is

usually of the comparati)e type; i.e. chec$ing against a $non defect. ,ddycurrent proes are often used to chec$ for defects inside holes >see diagramelo? and specially shaped proes may e used to chec$ items such as heelflanges and ead areas.

Re@e/ene P*ees. In order to calirate the e7uipment; standard referencepieces; manufactured from a material similar to that eing tested; are necessary.These pieces should contain defects of $non si=e or shape so that the changein coil impedance is $non. & typical reference piece ould contain three cuts at

different depths.



$.2.!.1 T-7*+, A77,*+t*ons o@ E- C//ent

In aircraft maintenance or$ eddy current testing may e used for crac$detection; conducti)ity testing or corrosion testing. The folloing applications aretypical applicationsJ

• C:e*n0 F+stene/ Ho,es @o/ C/+s

1. Clean loose paint; urrs; from inside and around holes eing chec$ed.

2. Calirate instrument in accordance ith manufacturers instructions

3. Insert proe in a hole in the reference piece and ad<ust for ma-imumdeflection from a selected notch or crac$

2. Insert proe in test specimen and rotate; noting any needle deflectionsgreater than that from reference proe. Chec$ other holes and re0chec$reference piece fre7uently.

2!. Ream out mar$ed holes i.a.. manufacturers instructions; repeat test

• C:e*n0 He+t D+6+0e S*n. The conducti)ity of aluminium alloy s$in illincrease ith e-posure to ele)ated temperatures up to appro-imately NCand the material ill e elo strength. &o)e this temperature; o)ioussigns of heat damage such as melted or charred metal ill ecome apparent.,ddy current tests ill sho the e-tent of the area in hich the material is

elo strength. & conducti)ity meter and a surface proe should e used forthis test. The meter should e =eroed on material of similar thic$ness to theaffected area. The conducti)ity around the affected area should then echec$ed; noting any deflections and mar$ing the s$in accordingly. "y thismeans a line may e dran around the affected area.

• Detet*on o@ Co//os*on. If a reading on normal thic$ness material can eta$enK since corrosion reduces the thic$ness of the metal; a different readingill e otained from corroded material. The e7uipment can e set up ynoting the reading otained from sound material of *\ thic$ness and thenchec$ing o)er the test specimen. ,7uipment is a)ailale hich is specificallydesigned for thic$ness measurement; ha)ing a meter calirated in thic$ness

units.

$.2.$'AGNETIC PARTICLE TESTING

'+0net* F,+= Detet*on. This method may e used to detect s/@+e andne+/ s/@+e defects in magnetic materials such as iron or steel. The techni7uema$es use of the distortion of magnetic fields y discontinuities at or near thesurface of a magnetised component. The distortion is highlighted y means of amagnetic poder applied to the surface; usually in the form of a magnetic in$sprayed on hile the component is magnetised.

& component is magnetised; either y passing a current through it; or y placingit in the field of a permanent magnet or electro0magnet. In either case; amagnetic field ill e set up in or around the component. :efects ill locallydistort this field; the ma-imum distortion eing otained hen the defect iseteen 4 and 13 degrees to the magnetic field.

There are )arious types of magnetising apparatus; ut they largely fall into tocategories.

• C//ent F,o= 'et:o. In this; electric current is passed through thecomponent and a strong magnetic field is set up at * degrees to the currentdirection. :efects in line ith the current ill e shon up est y thismethod. The current may e &C or :C; ut &C current is est for defectsclose to the surface and :C for deep defects. The specimen is usually

clamped eteen to contacts and the current may e as high as % amps.



• Int*on 'et:os. These methods use a coil hich induces a magneticfield into the specimen eing tested. The direction of the induced field is suchthat it passes through the specimen. This method is therefore est fordetecting trans)erse defects i.e. defects at right angles to the main a-is of thecomponent.

If the direction of defects is not $non; then oth methods may need to e used.Good lighting is re7uired in order to e-amine the defects and the componentmust e de0magnetised after testing. This is done y passing the component

through a de0magnetising coil supplied ith alternating current. Good lighting isalso re7uired for the e-amination of possile defects.

$.2.&RADIOGRAPHIC 'ISC. TESTING

$.2.&.1 R+*o,o0*+, e+6*n+t*on

Radiological e-amination of aircraft structures is recommended if the suspectedstructural area may e hidden or not easily accessile. :ue to the ha=ards of

radiation; it ill e necessary to isolate the aircraft and $eep personnel at a safedistance. The aircraft should e roped off ith radiation arning signs clearlyshon.

$.2.&.2 P/*n*7,es o@ R+*o0/+7:-

0rays and Gamma rays are radiations hich ha)e the aility to penetratematerials hich cannot e penetrated to )isile light. These radiations areasored in )arying degrees as they pass through the material and the degree ofasorption can e shon on a fluorescent screen or on a film. To main sourcesof radiation are commonly used i.e. 0rays and Gamma Rays.



• 9>/+-s are electronically produced y in an 0ray tue hich accelerateselectrons toards a metal target. n stri$ing the target; 0rays are produced.The a)elength of 0rays )aries from 1 mm >FsoftF 0rays? to 104 mm >FhardF0rays?. 9ard 0rays are capale of penetration mm thic$ steel. neimportant safety aspect is that 0rays are generated electrically and hencecan e sitched off.

• Gamma radiation results from disintegration of radioacti)e materials hichoccur naturally. Gamma radiation sources used in 6:T include Coalt !;

Iridium 1*2 and Bttererium 1!*; the numer folloing the element name isthe atomic mass. Gamma radiation can e-ist o)er similar a)elengths as 0Rays ith similar properties. Gamma radiation cannot e sitched off; it canonly e shielded.

$.2.&.3 S+@et- As7ets

The misuse of radiographic e7uipment could result in the release of physicallyharmful radiation and so operators must e properly trained and aare of thesafety regulations. Correct interpretation of results is also )ery important asincorrect conclusions could result in the clearance of unsound structures or thescrapping of safe structures. &ircraft radiological inspections should only e

carried out y personnel from organisations appro)ed under "C&R &'.perators ill e su<ect to fre7uent medical chec$s and ear a sensiti)e filmadge to detect the radiation dosage.

$.2.&.4 9>/+- F*,6

The films used in radiography are )ery similar to those used in photographye-cept that the emulsion is on oth sides of the transparent ase film. Theemulsion is sensiti)e to 0rays; Gamma rays and light and hen e-posed; achange ta$es place. /hen the film is de)eloped and fi-ed; an image is formed>radiograph?; the dar$ness of hich depends on the 7uantity of radiation passingthrough the specimenK the thic$er the specimen; the lighter the image. :efectssuch as a crac$ or porosity ill sho up as a dar$er area on the radiograph./hen ma$ing 0ray e-posures; the usual techni7ue is to put the 0ray or gammaray source on one side of the area to e tested and the film on the other side.

$.2.&.5 A*//+@t R+*o,o0-

The ma<ority of radiographs of aircraft structures are ta$en ith a portale 0rayset. This is ecause 0rays gi)e sharper images ith etter contrast thangamma ray sources. #sually; the radiation source is on the outside >or uppersurface? and the film is placed inside >or on the ottom surface?. ne ma<orad)antage of gamma radiation techni7ues is that the radioacti)e source is )erysmall and it can e placed inside o<ects such as engine parts; using guide tuesor handling rods attached to the containers and the film placed on the outside.

$.2.&." Inte/7/et+t*on o@ Res,ts

The accurate interpretation of defects indicated on the radiograph re7uires agreat deal of s$ill and a good $noledge of the aircraft structure. /ithout this$noledge it ould e easy for the engineer to o)erloo$ faults such as distortedor missing parts. ,)en the presence of leaded fuel in a tan$ ill mas$ defects.The interpretation may e simplified if radiographs of a sound structure area)ailale for comparison.

Radiographic inspection is often carried out during manufacture to chec$ formanufacturing faults such as loose articles; ri)etting faults and poor assemly

techni7ues. Some of the other indications found on radiographs are descried asfollosJ



• C+st*n0s +n We,s. 8etallurgical defects in castings and elds producepatterns recognisale y an e-perienced )ieer. Porosity ill reduce theamount of material through hich the rays must pass and a dar$er image illresult. Crac$s in elds are difficult to detect as the angle at hich theradiograph is ta$en is important.

• Co//os*on. This ill sho up as a fu==y image; ut the presence of paintand <ointing compound ill ma$e it difficult to detect. Inter0granular corrosionmay not e detected until it has reached an ad)anced state and affects the

metal surface. & corrosion pit; here there is a change in thic$ness is morereadily detected.

• C/+s. Stress crac$s often run along a line of ri)ets; ut the edge of <ointingcompounds used during the et assemly of ri)eted <oints often gi)es a falseindication. Radiographs may sho indications of crac$s; found to e crac$sin tan$ sealant. It is sometimes possile to open up tension crac$s eforeinspection y applying a tension load y <ac$ing.

$.2.1) 'ISC. TECHNI%UES

F,o/oso7-. The standard sheet film is replaced y a fluorosided screen. Thisenales mo)ing images to e captured. +or safety reasons a )ideo camera isfocused on the screen and the image )ieed at a safe distance. &n e-ample ofFfluoroscopyF is here oscillation in a turine shaft of gas turine engine eingFrunF can e oser)ed. & common e-ample is the lo energy -0ray of luggageeing inspected at airport departure security Fchec$0inF.

T:e/6o0/+7:-. & heat sensiti)e camera is used to inspect areas of aircraft inparticular composites. In the 7+ss*e mode the aircraft is inspected shortly afterlanding and temperature FcoldF spots ill indicate de0lamination or osmosis. The+t*e mode consists of microa)e radiation eing targeted at suspectcomponents ith the area eing inspected y the camera in the same ay as thepassi)e mode.



$.3 TYPES OF DEFECT AND (ISUAL INSPECTION TECHNI%UES

The term HInspection is used e-tensi)ely in all al$s of life; in a )ariety ofdifferent circumstances. /hat does it mean though The Concise -ford:ictionary defines HInspect as H5oo$ closely into or e-amine officially. &nInspector is defined as Hne ho inspects or an official employed to super)ise aser)ice.

$.3.1INSPECTION

To aircraft engineers; inspection can mean a )ariety of things. ne of the maintas$s carried out ill e Scheduled 8aintenance Inspections >S8IDs?. These arespecial inspections detailed y the manufacturer; carried out a specified timeperiod. /hen carrying out this inspection the ultimate aim is to ensure that theaircraft or part eing inspected is in a safe condition or that it complies ith theoriginal design specification. The type of inspection carried out ill depend on a)ariety of factors.

• The nature of the item eing inspected i.e. the material it is made from. It maye metallic; plastic; ruer or any other type of material.

• The purpose of the inspection. It may e to estalish hether the item issuffering from a $non fault.

• The location of the item to e inspected. It may e fitted to an aircraft orremo)ed from an aircraft. In most cases the maintenance schedule illspecify that an item is alays inspected ithout remo)al from the aircraft. Theterm Hin0situ is usually applied in this case.

• Is the inspection internal or e-ternal. The normal con)ention is thatinspections are e-ternal unless otherise stated.

• The degree or depth of the inspection. 9o closely do e e-amine acomponent :o e use magnifying aids or specialised techni7ues such as

6on0:estructi)e ,-amination• The time a)ailale for the inspection. This is often dictated y circumstances.

If you are told to go out and inspect a tyre for ear; you should e ale tochec$ it in a fe minutes. & ma<or aircraft inspection on a large aircraft;hoe)er; is normally planned to ta$e many days.

$.3.2WHAT TYPE OF DEFECTS

The manufacturer should specify hat to inspect for. The depth of inspection isoften at the discretion of the person carrying out the inspection. In most cases theinspector is loo$ing for indications of anormality in the item eing inspected. "ythis I mean that he@she is loo$ing for something different or o)ious indication

that the item is anormal. &s suggested earlier; hat you loo$ for ill dependlargely on the material of the item you are inspecting. Typical e-amples assuggested y H"oeing areJ

1. 8etal PartsJ &s applicale to all metal parts; odies or casings of units insystems and in electrical; instrument and radio installations; metal pipes;ducting; tues; rods and le)ers. Inspect forJ

• Cleanliness and e-ternal e)idence of damage

• 5ea$s and discharge

• )erheating

• +luid ingress

• struction of drainage or )ent holes or o)erflo pipe orifices



• Correct seating of panels and fairings and ser)iceaility of fasteners.

Inspect also for freedom fromJ

• :istortion; :ents; Scores; Chafing

• Pulled or missing fasteners; ri)ets; olts or scres

• ,)idence of crac$s or ear

• Separation of adhesi)e onding

• +ailures of elds or spot elds

• :eterioration of protecti)e treatment and Corrosion

• Security of attachments; fasteners; connections; loc$ing and onding

2%. Ruer; +aric; Glass +ire and Plastic Parts e.g. co)erings; ducting; fle-ilemountings; seals; insulation of electrical cales; indos. Inspect forJ

• Cleanliness

• Crac$s; cuts; chafing; $in$ing; tisting; crushing; contraction sufficient free length

• :eterioration; cra=ing; loss of fle-iility

• )erheating

• +luid soa$age

• Security of attachment; correct connections and loc$ing

2'. Control System Components. Inspect forJ

• Correct alignment no fouling

• +ree mo)ement; distortion; e)idence of oing

• Scores; chafing; fraying; $in$ing• ,)idence of ear; flattening

• Crac$s; loose ri)ets; deterioration of protecti)e treatment and corrosion

• ,lectrical onding correctly positioned; un0damged and secure

• &ttachments; end connections and loc$ing secure

2*. ,lectric 8otors; &lternators; Generators and &ctuators. Relays; solenoids andcontactors. Inspect forJ

• Cleanliness; o)ious damage

• ,)idence of o)erheating• Corrosion and security of attachments and connections

• Cleanliness; scoring and orn rushes; ade7uate spring tension afterremo)al of protecti)e co)ers

• )erheating and fluid ingress

• Cleanliness; urning and pitting of contacts

• ,)idence of o)erheating and security of contacts after remo)al ofprotecti)e co)ers



$.4 TROU#LE SHOOTING TECHNI%UES

Trouleshooting is the process of identifying the cause of a fault; eliminating thefault and returning the aircraft to ser)ice. The main aim is to return the aircraft toan airorthy condition ith a high proaility of the fault 6T re0occurring. &nengineer cannot ensure that the fault ill not re0appear in ser)ice; ut he@sheshould ma$e an attempt to permanently fi- the fault.

$.4.1CONFIR'ATIONIDENTIFICATION OF THE FAULT

ne of the most common mista$es made in the trouleshooting process is failureto correctly identify the fault. The fault ill often e reported incorrectly. Time cane sa)ed y carrying out a functional test to confirm the e-act fault. It is also iseto try to get as much information as possile from the pilot or person hodisco)ered the fault. Questions should e as$ed such asJ

• /as the system or$ing perfectly efore you noticed the fault

• :id the system or$ in manual if it is an automatic system

• /hat altitude ere you at and hat speed

$.4.2FAULT FINDING TECHNI%UES

+ault finding is proaly the most difficult s$ill for an engineer to learn. 9e or shemust normally e )ery familiar ith the asic theory and ha)e a detailed$noledge of a particular aircraft system. In many cases; an engineer ith manyyears e-perience may ha)e come across an identical fault. +ault finding is alsocarried out y pure guessor$; or y replacing the component most a)ailale oreasiest to replace; and then the ne-t easiest etc.. This is called Hshotgunmaintenance in the #S&. If you are luc$y; the aircraft is e7uipped ith systemthat do the hard or$ for you. Some aircraft ha)e on0oard maintenancecomputers that identify faults and store them ready for donloading on theground. 8anufacturers ha)e also de)eloped sophisticated Troule Shooting or+ault Isolation 8anuals that ta$e the guessor$ out of the system.

$.4.3ON #OARD 'AINTENANCE SYSTE'S

n oard maintenance systems are the latest de)elopment in aircraft a)ionics.They egan ith simple press to test uttons and failure flags fitted to indi)idualitems in the coc$pit. These re7uired human action and recorded no data. &utopilot systems ere the dri)ing force ehind de)elopment of a ettermaintenance system to emrace all of the autopilot functions and itscomponents; ith the intention of meeting the integrity and certificationre7uirements of autoland. The )ery high safety le)el specified for autoland couldonly e attained using redundancy in a systemK this implied self0test andreporting to estalish that the system as functioning correctly. In the earlyanalogue electronic autoland systems this remained part of the components; utthe introduction of airorne digital computers made it possile to use a centralcomputer for monitoring and display of system performance.

& dedicated maintenance control and display unit >8C:P? as fitted to "oeing%% and %!% aircraft; hich entered ser)ice in the early 1*'Fs. The similarfunction on "oeing %3% aircraft as automated using the control and display unit>C:#? of the performance data computer >P:C? for the %3% 2 series; and theflight management computer >+8C? of the %3% 3 series aircraft.



The "oeing %% and %!% also introduced the engine indicating and cre alertingsystem >,IC&S? this forms part of the Mglass coc$pitM; as it is popularly $non.This is a maintenance significant system; ith data displays for engines; &P#;electrical; hydraulic; and en)ironmental control systems. In addition; dispatchcritical maintenance data are displayed in the form of status messages as part ofthe caution and arning function.

$.4.4FAULT ISOLATION 'ANUALTROU#LE SHOOTING 'ANUAL

These are pro)ided y the manufacturers to help identify; isolate and remo)efailures found in flight and on the ground. In the case of the "oeing +ault Isolation8anual >+I8? the manual is used in con<unction ith the +ault Reporting 8anual>+R8? that gi)es an eight0digit fault code. & flochart is then used to diagnosethe fault and to repair the failure.



&. A#NOR'AL E(ENTS

&.1 INTRODUCTION

8ost modern aircraft are designed to ithstand the normal flight and landingloads e-pected during flight. These ill include the normal manoeu)res theaircraft is e-pected to ma$e. The designer ill uild in a safety factor tocompensate for loads slightly larger than normal. Sometimes e-treme

circumstances occur hich cause stresses outside the normal design limits.

If the design limits are e-ceeded; damage may occur to the aircraft. If it is $nonor suspected that the aircraft has een su<ected to e-cessi)e loads; then aninspection should e carried out to ascertain the nature of any damage that mayha)e occurred. The manufacturer ill normally ha)e anticipated the nature ofsome of these occurrences and detailed special chec$s for these H&normalccurrences.

&.2 TYPES OF A#NOR'AL OCCURRENCE

The aircraft maintenance manual ill normally list the types of anormal

occurrence needing special inspection. The list may )ary depending on theaircraft. The folloing items are a selection from a typical aircraftJ

• 9ea)y or o)ereight landing

• "urst Tyre

• +light through se)ere turulence

• +lap or slat o)er0speed

• +light through )olcanic ash

• Tail stri$e

• 8ercury spillage

• :ragged engine or engine sei=ure

• 9igh energy stop

&.3 TYPE OF DA'AGE

It is not intended for us to descrie the type of damage applicale to e)ery type ofoccurrence. It is more important to understand that in many cases the damagemay e remote from the source of the occurrence. In many cases the inspectionould e carried out in to stages. If no damage eing found in the first stagethen the second stage may not e necessary. If damage is found; the second

stage inspection is carried out. This is li$ely to e a more detailed e-amination.

&.4 LIGHTING STRIKES HIRF PENETRATION

"oth lightning stri$es and 9igh Intensity Radiated +ields >9IR+? are discussed in8odule . 5ightning eing the discharge of electricity in the atmosphere; usuallyeteen highly charged cloud formations; or eteen a charged cloud and theground. If an aircraft is flying in the )icinity of the discharge or it is on the ground;the lightning may stri$e the aircraft. This ill result in )ery high )oltages andcurrents passing through the structure.

&ll separate parts of the aircraft are electrically onded together to pro)ide a loresistance path to conduct the lightning aay from areas here damage mayha=ard the aircraft.



&.4.1EFFECT OF A LIGHTNING STRIKE

5ightning stri$es are li$ely to ha)e to main effects on the aircraftJ

• Stri$e damage here the discharge enters the aircraft. These ill normally eon the e-tremities of the aircraft; the ing tips; nose cone and tail cone andon the leading edge of the ings and tailplane. The damage ill usually e inthe form of small circular holes; usually in clusters and accompanied yurning or discoloration.

• Static discharge damage at the ing tips; trailing edges and antenna. Thedamage ill e in the form of local pitting and urning. "onding strips andstatic ic$s may also disintegrate due to the high charges.

&.4.2INSPECTION

The maintenance schedule or maintenance manual should specify theinspections applicale to the aircraft. The areas specified in paragraph *.4.1should e e-amined for signs of stri$e or discharge damage. "onding straps andstatic discharge ic$s should e chec$ed for damage. :amaged onding strapson control surfaces may lead to trac$ing across control surface earings; this inturn may cause urning; rea$ up or sei=ure due to elding of the earings. This

type of damage may result in resistance to mo)ement of the controls. This can echec$ed y carrying out a functional chec$ of the controls. &dditional chec$s mayincludeJ

• ,-amine engine colings and engines for e)idence of urning or pitting. &s incontrol earings; trac$ing of the engine earings may ha)e occurred.8anufacturers may recommend chec$ing the oil filters and chip detectors forsigns of contamination. This chec$ may need to e repeated for a specifiednumer of running hours after the occurrence.

• ,-amine fuselage s$in; particularly ri)ets for urning or pitting.

• If the landing gear as e-tended; some damage may ha)e occurred to the

loer parts of the gear. ,-amine for signs of discharge.• &fter the structural e-amination it ill e necessary to do functional chec$s of

the radio; radar; instruments; compasses; electrical circuits and flyingcontrols. & onding resistance chec$ should also e carried out.

&.4.3HIGH INTENSITY RADIATED FIELDS ;HIRF<

8odule discusses electromagnetic phenomena; in particular the prolem ofelectromagnetic interference. This may e from an internal or e-ternal source.9IR+ may e generated y airorne transmitters such as high0poered radar orradio. 9IR+ may e transmitted y military aircraft in close pro-imity tocommercial aircraft. Increased use of digital e7uipment has increased the

prolem.

&.4.4PROTECTION AGAINST HIRF

The manufacturer ill normally protect the aircraft against 9IR+. This is normallyachie)ed y onding; shielding and separation of critical components. It is difficultto $no hen the aircraft has een su<ected to 9IR+; conse7uently protection isest achie)ed y regular chec$s ofJ

• "onding of the aircraft

• Correct crimping

• Screens correctly terminated and earthed• &ll onding terminals correctly tor7ue loaded



&.5 TYPICAL 'ANUFACTURERS INFOR'ATION ;#OEING !5!<

&.5.1GENERAL INFOR'ATION

This procedure is an e-tract from the "oeing %% 8aintenance 8anual. It isincluded to gi)e you an idea of a typical aircraft inspection procedure. 6ot all ofthe details ha)e een supplied; ut there is enough information to gi)e you ageneral idea. Bou ill not e e-amined in detail on this procedure; ut you should

e ale to identify specific chec$s that highlight the pre)ious notes.

This procedure has these three tas$sJ

• ,-amine the ,-ternal Surfaces for 5ightning Stri$e

• ,-amine the internal Components for 5ightning Stri$e

• Inspection and perational Chec$ of the Radio and 6a)igation Systems

&.5.2#ASIC PROTECTION

The aircraft has all the necessary and $non lightning stri$e protectionmeasures. 8ost of the e-ternal parts of the aircraft are metal structure ith

sufficient thic$ness to e resistant to a lightning stri$e. This metal assemly is itsasic protection. The thic$ness of the metal surface is sufficient to protect theinternal spaces from a lightning stri$e. The metal s$in also gi)es protection fromthe entrance of electromagnetic energy into the electrical ires of the aircraft.The metal s$in does not pre)ent all electromagnetic energy from going into theelectrical iringK hoe)er; it does $eep the energy to a satisfactory le)el. Iflightning stri$es the aircraft; you must fully e-amine all of the aircraft to find theareas of the lightning stri$e entrance and e-it points /hen you loo$ at the areasof entrance and e-it; e-amine this structure carefully to find all of the damage thathas occurred

&.5.3STRIKE AREAS

5ightning stri$e entrance and e-it points are usually found in [one 1 >Seefolloing diagram?; ut also can occur in =ones 2 and 3. Bou can usually findsigns of a lightning stri$e in [one 1. 9oe)er; lightning stri$es can occur to anypart of the aircraft; including the fuselage; ing s$in trailing edge panels. ing0ody fairing; antennas; )ertical stailiser; hori=ontal stailiser; and along the ingtrailing edge in [one 2.

&.5.4SIGNS OF DA'AGE

In metal structures; stri$e damage usually shos as pits; urn mar$s or smallcircular holes. These holes can e grouped in one location or di)ided around a

large area. "urned or discoloured s$in also shos lightning stri$e damageIn composite >non0metallic? structures; solid laminate or honeycom damageshos as discoloured paint it also shos as urned; punctured; or de0laminateds$in plies. :amage you can not see can also e there. This damage can e-tendaround the area you can see. Signs of arcing and urning can also occur aroundthe attachments to the supporting structure

&ircraft components made of ferromagnetic material may ecome stronglymagnetised hen su<ected to large currents. 5arge current floing from thelightning stri$e in the aircraft structure can cause this magnetisation.



&.5.5E9TERNALCO'PONENTS

& lightning stri$e usually attaches to the aircraft in [one 1 and goes out adifferent [one 1 area. +re7uently a lightning stri$e can enter the nose radomeand go out of the aircraft at one of the hori=ontal stailiser trailing edges. Thee-ternal components most li$ely to e hit are listed eloJ

&. 6ose Radome

". 6acelles

C. /ing Tips

:. 9ori=ontal Stailiser Tips

,. ,le)ators



+. (ertical +in Tips

G. ,nds of the 5eading ,dge +laps

9. Trailing ,dge +lap Trac$ +airings

I. 5anding Gear

A. /ater /aste :rain 8asts

E. Pilot Proes

&.5."ELECTRICAL CO'PONENTS

5ightning stri$es can cause prolems to the electrical poer systems and thee-ternal light iring The electrical system is designed to e resistant to lightningstri$es. "ut; a stri$e of unusually high intensity can possily damage the electricalsystem components eloJ

&. +uel )al)es

". Generators

C. Poer +eeders

:. ,lectrical :istriution Systems

,. Static :ischarge /ic$s

6T,J lf inaccuracies in the standy compass are reported after a lightning stri$ethen a chec$ sing ill e necessary.

+re7uently; a lightning stri$e is referred to as a static discharge. This is incorrectand may cause you to thin$ that me static discharge ic$s; found on the e-ternalsurfaces of the aircraft pre)ent lightning stri$es. These static discharge ic$s arefor leeding off static charge onlyK they ha)e no lightning protection function. &sthe aircraft flies through the air; it can pic$ up a static charge from the air >ordust@ater particles in the air?. This static charge can ecome large enough toleed off the aircraft on its on. If the charge does not leed off the aircraft on itson; it ill usually result in noise on the (9+ or 9+ radios. The static dischargeic$s help to leed the static charge off in a ay that pre)ents radio noise

The static discharge ic$s are fre7uently hit y lightning. Some personnel thin$static dischargers are for lightning protection. The dischargers ha)e the capacityto carry only a fe micro0&mps of current from the collected static energy. Theappro-imate 2; &mps from a lightning stri$e ill cause damage to thedischarge ic$ or ma$e it fully unser)iceale

&.5.!E9A'INATION OF E9TERNAL SURFACE

,-amine the [one 1 surface areas for signs of lightning stri$e damage. :o thee-aminations that folloJ

&. ,-amine the e-ternal surfaces carefully to find the entrance and e-itpoints of lightning stri$e.

". 8a$e sure to loo$ in the areas here one surface stops and anothersurface starts.

C. ,-amine the internal and e-ternal surfaces of the nose radome forurns; punctures; and pinholes in the composite honeycom sandichstructure.

:. ,-amine the metallic structure for holes or pits; urned or discoloureds$in and ri)ets.

,. ,-amine the e-ternal surfaces of the composite components fordiscoloured paint; urned; punctured; or de0laminated s$in plies.

+. Bou need to use instrumental 6:I methods or tap tests to find

composite structure damage you cannot see.



6oteJ :amage; such as de0lamination can e-tend to the areas around thedamage area you can see. :e0lamination can e detected y instrumental6:I methods or y a tap test. +or a tap test; use a solid metal disc and tapthe area ad<acent to the damaged area lightly. If there is de0lamination; youill hear a sound that is different to the sound of a solid onded area.

G. ,-amine the flight control surfaces for signs of stri$e damage. If thecontrol surfaces sho signs of damage; e-amine the surface hinges;earings and onding <umpers for signs of damage.

9. If the ailerons sho signs of a lightning stri$e; e-amine the surfacehinges; earings; and onding <umpers for signs of damage.

I. If the speed ra$es sho signs of a lightning stri$e; e-amine thesurface hinges; earings; and onding <umpers for signs of damage.

A. If the trailing edge flaps sho signs of a lightning stri$e; e-amine thesurface hinges; earings; and onding <umpers for signs of damage.

E. If the leading edge flaps@slats sho signs of a lightning stri$e; e-aminethe surface hinges; earings; and onding <umpers for signs ofdamage.

5. ,-amine the nose radome for pin holes; punctures and chipped paint. &lso ensure onding straps are correctly attached. ,-amine the

lightning di)erter strips and repair or replace them if damaged. If thereis radome damage; e-amine the /R antenna and a)e0guide fordamage.

&.5.$FUNCTIONAL TESTS

+unctional tests ill need to e carried out as follosJ

&. ,nsure the na)igation lamps; rotary lights and landing lights operate.

". If the ao)e control e-aminations sho signs of damageJ :o anoperational test of the rudder if there are signs of lightning stri$edamage to the rudder or )ertical stailiser.

C. :o an operational test of the ele)ator if there are signs of lightningstri$e damage to the ele)ator or hori=ontal stailiser.

:. :o an operational test of the ailerons if there are signs of lightningstri$e damage to the ailerons.

,. :o an operational test of the speed ra$es if there are signs of lightningstri$e damage to the speed ra$e system.

+. :o an operational test of the trailing edge flaps if there are signs oflightning stri$e damage to the trailing edge flaps.

G. :o an operational test of the leading edge flap@slats if there are signs oflightning stri$e damage to the trailing edge flap@slats.

9. If there are signs of stri$e damage to the landing gear doors; disengage

the main gear door loc$s and manually mo)e the doors to ensure theymo)e smoothly. (isually e-amine the door lin$age; hinges; earingsand onding <umpers for stri$e damage. ,nsure the pro-imity sitchindication unit gi)es the correct indication.

&.5.&E9A'INATION OF INTERNAL CO'PONENTS

If a lightning stri$e has caused a system malfunction; do a full e-amination of thesystem.

&. :o a chec$ of the stand0ye compass system if the flight cre reporteda )ery large compass de)iation.

". 8a$e sure the fuel 7uantity system is accurate. This can e achie)ed

y a "IT, test.



C. ,-amine the air data sensors for signs of stri$e damage. :o anoperational test of the pitot system if there are signs of damage to theproes. :o a test of the static system if there are signs of damage nearthe static ports.

:. :o an operational chec$ of any of the folloing systems that did notoperate folloing the stri$e; or if the flight cre reported a prolem; or ifthere as any damage found near the system antenna.

i. 9+ communications system

ii. (9+ communications system

iii. I5S na)igation system

i). 8ar$er eacon system

). Radio altimeter system

)i. /eather radar system

)ii. (R system

)iii. &TC system

i-. :8, system

-. &utomatic :irection +inder >&:+? system

If one or more of the pre)ious systems ha)e prolems ith their operationalchec$s; e-amine and do a test of the coa-ial cales and connectors.

&.5.1) RETURN THE AIRCRAFT TO SER(ICE

&fter all areas ha)e een inspected and lightning damage has een repaired;

components replaced as necessary and tests completed if necessary; the aircraftmay e returned to ser)ice.



P+0e Intent*on+,,- #,+n



1). 'AINTENANCE PROCEDURES

1).1 'ODIFICATION PROCEDURES

&n aircraft manufacturer ill initially design and uild the aircraft to a specificationas agreed y the regulatory ody >A&&; C&& or +&& as applicale?. The aircraftill then gain its type certificate from the regulatory ody. It ill then e permittedto fly; pro)ided it is maintained in accordance ith the appro)ed maintenance

schedule. If any change is made to the design of the aircraft or its components;the aircraft is o)iously different from the specification. This change ill edeemed to e a modification that ill therefore re7uire the appro)al of the designauthority. 8odifications ill e re7uired for )arious reasonsJ

• & change of some sort is re7uired; generally to impro)e reliaility;accessiility or possily to meet an operational need. The operator ill;therefore; raise a modification to suit their re7uirements.

• & manufacturer rings out a modification; hich is considered to e animpro)ement to the aircraft or component. Generally the manufacturer illneed to get the modification appro)ed y the Responsile &uthority.8anufacturersF modifications ill e classified either as 6+n+to/- or non0

mandatory. If mandatory; the aircraft operator 6st incorporate themodification. If non0mandatory o/ /eo66ene; its emodiment ill e atthe discretion of the operator. If the modification affects the safety of theaircraft; it ill alays e declared mandatory.

• The Responsile &uthority may decide an impro)ement is necessary and illre7uest a manufacturer to produce a modification to ma$e the impro)ement.

1).1.1 DESIGN 'ODIFICATIONS

&s stated earlier; the regulatory authority must appro)e a modification. /e illno loo$ at the procedure y hich a modification is appro)ed. The C&&according to their effect on airorthiness ill classify any modification as 6*no/or 6+o/ . If any changes should e made to the flight manual or any otherairorthiness pulication; the modification ill e deemed ma<or. It is necessary;therefore; those particulars of the modification should e pro)ided to the C&& atan early stage of the in)estigation; to enale the classification to e carried out.

&n application for a '*no/ 'o*@*+t*on is made to the C&& on +orm &:2!1.The C&& ill appro)e the minor modification y returning a copy of thecompleted +orm &:2!1 >see folloing page? to the applicant. rganisationsappro)ed for the purpose may design and carry out a minor modification ithoutfull C&& modification appro)al. They must; hoe)er; otain initial confirmationthat the modification is 6*no/ .

'+o/ 'o*@*+t*ons. C&& +orm &:2'2 >see folloing page? otainale fromthe C&&; must e completed y the applicant. The C&& ill then carry out thenecessary in)estigation 0 the total fee to e paid ill depend on the amount ofin)estigation re7uired and ill e)entually signify its appro)al of a 6+o/modification y forarding to the applicant a copy of the A*/=o/t:*nessA77/o+, Note. The &&6 ill ha)e a reference numer; hich must e enteredon all documentation dealing ith the modification and especially in the logoo$s.

&ll #E Registered &ircraft o)er 2%3$g re7uire a separate record of allmodifications >including &irorthiness :irecti)es? to e $ept. +or light aircraft thisrecord is $ept in the aircraft 5ogoo$. +or larger aircraft a separate 8odificationRecord "oo$ >C&P 3*? must e $ept complete ith full details of allmodifications and inspections carried out. The C**, 'o*@*+t*on Reo/ shall

e made a)ailale to the C&& for e-amination.



The He6o*6ent of a modification must e carried out y an appro)edorganisation or an appropriately licensed aircraft maintenance engineer and therele)ant entries made in the appropriate log oo$>s?; 7uoting references and aCRS signed. If the or$ is signed for on a separate record; e.g. a or$sheet; anentry may e made in the logoo$ 7uoting the reference of the separate recordand here it is held. The entry should refer to the modification@ inspectionnumer.

:epending on the nature of the modification; it may e necessary to eigh and@or

test fly the aircraft. 8anuals may also re7uire amendment e.g. +light 8anual;8aintenance 8anuals and; sometimes; the C of & particulars may e amended.If the +light 8anual or Certificate of &irorthiness re7uires amendment; it shoulde forarded to the local area office of the C&& for chec$ing.



1).2STORES PROCEDURES

1).2.1 APPRO(ED PARTS

8ost of the aircraft parts that an engineer uses ill e Controlled Items; that is;they ha)e to e produced y &ppro)ed rganisations and certified as &ppro)edparts or components. Some parts; hich ould not ad)ersely affect theairorthiness and the safe operation of an aircraft >if they failed?; are not re7uired

to e appro)ed and are classified as #ncontrolled Items. &n e-ample ould ecain ser)ice e7uipment. 6e)ertheless; the organisation designing the aircrafthas to certify to the C&& that it is satisfied that no uncontrolled item installed inthe aircraft ill constitute a danger to the aircraft?.

&ircraft parts and components; folloing receipt from the supplier; ill ha)e to estored under acceptale conditions until they are installed in an aircraft. In thissection e ill loo$ at the ay that aircraft parts are stored prior to their use onaircraft.

1).2.2 GOODS INWARD PROCEDURE

5et us consider the procedures to e folloed from the receipt of the componentsat the operating company. In a A&R 14 appro)ed company there ill e aGoods Inard or Goods Receipt Section. This is here parts ill initially e senty the supply organisation. This must e separate from the main storage area. Itmay e as ell at this stage to state the to types of Store area; hich must e-istin an organisation. These need not e separate uildings; ut they must eseparate from each other.

%+/+nt*ne Sto/e 0 This is here all nely recei)ed parts must e placed until itis confirmed that the parts are appro)ed items and undamaged. The GoodsInards@Receipt Section ill e part of the Quarantine Store. #nser)icealeitems aaiting disposal or to e sent out for o)erhaul@repair; or scrap may also eheld in the Quarantine Store; the aim eing to 7uarantine them i.e. pre)ent any

possiility of them eing mi-ed up ith ser)iceale items ith the ris$ that theycould e put into use.

#one Sto/e 0 This should contain only those materials and parts intended foraeronautical purposes that conform to all re7uirements i.e. they are appro)edand ser)iceale.

It should e appreciated that in most cases; parts ill ha)e een ordered from an &ppro)ed supplier on a Purchase rder. This ill ha)e an indi)idual referencenumer. Parts @ components that ha)e een sent out for o)erhaul or repair illalso ha)e some form of document raised y the )erhaul@repair Company. Thecomponents ordered ill normally e deli)ered to the Goos In=+/ Sto/es y acompany such as +ederal ,-press or T.6.T. as a single component in a o-; or

as part of a ul$ deli)ery. There should e some form of Goods InardInspection carried out y the stores to ensure the parts are satisfactory. Thefolloing descries a typical Goods Inards ProcedureJ

n receipt of a pac$age in the Goods Receipt Section; it should e e-amined fordamage. Should the pac$age sho signs of damage e.g. a crushed corner; itshould e noted and efforts made to $eep the e)idence. If the pac$age is $nonto contain delicate parts such as an aircraft instrument; consideration should egi)en to returning the pac$age unopened. +e operating companies ill ha)ethe facilities to pro)e the ser)iceaility of such items.



&ssuming the pac$aging is sound; it should e opened and the items remo)edand inspected for damage. /ith the pac$age there should e a pac$ing ordeli)ery note and some type of &uthorised Release :ocument. The &uthorisedRelease :ocument is the proof of conformation of design for the item and may ea A&& &ppro)ed Certificate >A&& +orm 1? or +&& +orm '13 or some other formof certification. +or the enefit of this e-ercise e shall assume an &ppro)edCertificate is used. Chec$ the items to the pac$ing note and the certificateensuring that all is in order. &lso chec$ the items recei)ed conforms to theP/:+se O/e/ . The correct part numer has een suppliedK that if an o)erhaul

as ordered; an o)erhaul has een carried out and not <ust a repair. If a specifictest or caliration as re7uested; chec$ it has een done and the necessarycertification is as re7uired.

• Should the At:o/*se Re,e+se Do6ent e missing; the pac$age anditems 8#ST e held in 7uarantine until it arri)es 0 the components cannot eused ithout the correct certification.

• The cleared consignment should no e F"oo$ed intoF the Stores. & record is$ept of the se7uence in hich items are recei)ed; the &ppro)ed Certificatenumer; date of receipt; name of supplier; description; any shelf lifelimitations and the signature of the authorised person responsile for receiptof the goods. If this is done; the component history can e traced in thee)ent that the item fails in ser)ice.

• This F"oo$ing InF procedure may ta$e any form pro)ided it satisfies the C&&re7uirements. ne method used in the Goos Ree*e Note system>GR6? GR6Fs are printed in pads; generally in triplicate. &nother commonlyused method is a computerised dataase of stores items. The Stores datamay e directly lin$ed ith other parts of the maintenance organisation; suchas P/:+s*n0 and Te:n*+, Reo/s.

• GR6Fs may e gi)en consecuti)e numers hen printed. 8ore commonly; anumer is allocated se7uentially y the Goods Inards Inspector. TheGoods Recei)ed 6umer or "atch 6umer; can follo a pattern determined

y the date and the order in hich consignments are recei)ed. &n e-ampleof such a numering system ould e to start the numer ith the month andthe yearK folloed y the consignment numer for that month e.g. the 2'thpac$age recei)ed in Septemer 1**' ould e numered **'@2'. If thepac$age contains more than one item; and therefore a numer of items onthe &ppro)ed Certificate; each item ill e itemised on the certificate and thisis addressed to the GR or "atch 6o. e.g. the 3rd item on the &ppro)edCertificate of our pac$age in Septemer 1**' ould end up ith the numer**'@2'@3. The ad)antages of such a system ill e seen in a minute. +orthe moment let us assume this is the method e are going to use andtherefore the Goods Inards Inspector recording receipt of a pac$age illstart a ne Goods Recei)ed 6ote putting the numer **'@2' on the top. 9e

ill then list all the necessary details on to the sheet itemising each as rittenon the &ppro)ed Certificate; so 6o03 on the GR6 ill e 6o.3 on the &ppro)ed Certificate 0 the GR 6o. for this item ill therefore e **'@2'@3.

&mongst the details recorded on the GR6 ill e the &ppro)ed Certificate6umer; the supplier; date; description; Part 6o. Serial 6o. >if applicale?; statusof component 0 ne; o)erhauled; repaired; TS6; TS; and any other rele)antdetails shon on the &ppro)ed Certificate. &dditionally; the Purchase rdernumer ill e recorded on the GR6. The Goods Inards Inspector ill sign theGR6.



GRN )&&$2$

GRN D+te A77/oeCe/t. No.

S77,*e/ Des/*7t*on P+/tNo

Se/*+,No.

St+ts TSNTSO

P/:+seO/e/

S*0n.

1

2

3

4

5

"

!

$

&

1)



E+67,e o@ + t-7*+, Goos Ree*e Note



The ad)antages of this GR6 system should e considered.

• The top copy of the GR6 is filed in numer; i.e. date order and forms theGoods Recei)ed Record.

• ther copies of the GR6 are sent toJ

• Technical Records so that they are informed of the receipt of the partand can raise a component card; if applicale; or up0date thecomponent card of any item recei)ed ac$ from o)erhaul@repair and

place the card in the Stores file indicating its location.

• The &ccounts :epartment to inform them of receipt so that they canchec$ it against the in)oice demanding payment and clear the payment>the Purchase rder numer is the lin$ here?.

• The GR numer is ritten on top of the &ppro)ed Certificate and filed aay inGR numer order. &ppro)ed Certificates come in a )ariety of si=es and ithan e)en greater )ariety of reference numers depending on the suppliers; sothat trying to file them in a suitale order so that 7uic$ retrie)al is possile is)ery difficult indeed. If each &ppro)ed Certificate has a GR or "atch numer;it can e filed in that numer order. Pro)ided the item is identified ith the

GR or "atch numer from this point on; in the "onded Store; hen installedin an aircraft; it ill alays e easy to refer to the &ppro)ed Certificate shouldit e necessary.

• The GR numer ased on the month and year **' is a permanent record ofhen the item as recei)ed at the company.

The ne-t action of the Goods Inards Inspector is to raise a sto/es ,+e, that ille attached to the item or its pac$aging. The Stores lael ill e filled in ith:escription; Part and@or Serial 6umer as applicale. &lso the status 0 neo)erhauled@repaired; GR or "atch 6o. >&ppro)ed Cert. numer if GR or "atchnumer system not used?; Shelf 5ife if applicale and any other details thecompany may re7uire such as &ircraft Type.

The item can no e passed into the "onded Store; it ha)ing een confirmed asan appro)ed; ser)iceale part. The "onded Store$eeper enters the item into theStores Record System. &n inde-ed card system is a common method; each cardeing filed in Part 6umer order. ther details ill e recorded such asdescription; location stored or "in numer; 7uantity in stoc$; minimum stoc$le)els and re0order 7uantities. 5arger organisations ill use a computeriseddataase system ith the same type of information recorded. There may also ea Shelf 5ife "oo$. This may ha)e separate pages headed y month and year forthe foreseeale future. ,ach item is entered on to the page hen its shelf lifee-pires; or 3 months ahead of that point to enale its use to e planned eforee-piring.



/hen an item is dran from the Store for installation on an aircraft; the part ille identified using the Part 6umer. The inde-ed card or dataase system maye chec$ed to find out ho many are in stoc$ and here stored. 6ormally thefirst item recei)ed into the store ill e issued >+irst in; +irst ut or +I+?. Thisprocedure may e )aried if a component is held ith only part life remaining 0either a repaired item or a ser)iceale item hich has een remo)ed from anaircraft and returned into the stores system. The decision must e made if apart0life item is acceptale or if an item ith a full o)erhaul life remaining isre7uired.

The item ill e issued on a 8aterials Issue (oucher or similar sheet generallyheaded y the Ao 6umer and listing the description Part 6umer; serialnumer; if applicale; and GR or "atch numer. /hen the <o is completed; acopy of this )oucher is sent to Technical Records for inclusion in the /or$ pac$.The Store$eeper ill then up0date the record cards or dataase; shoing theitem has een issued to the Ao 6umer and deleting the item from his shelf0lifeoo$ if applicale.

If management has decided that replacement items must e ordered hen thestoc$ reaches a certain point; this ill e shon on the Stores Record Cards andthe Store$eeper ill initiate a re7uisition so that a Purchase rder ill e raisedon a supplier for the re7uired amount. /ith a dataase system; this may e

automatic.

The engineer installing the item on the aircraft ill ha)e all the informationneeded for the logoo$ entry on the Stores 5ael; including the GR or "atch6umer hich ill enale the history of the item to e chec$ed ac$ to the &ppro)ed Certificate if necessary.

1).2.3 STORAGE CONDITIONS

C.&.&.I.P 5eaflet 10' gi)es information on acceptale conditions for the storageof aeronautical supplies. This information may e used in the asence of anyspecific manufacturerFs recommendations.

In particular; the need for )entilation; and the aility to monitor and controltemperature and humidity to pre)ent condensation is mentioned.

:ifferent items ill re7uire different storage procedures. Some of the specificprocedures are shon eloJ

• 5ead &cid and 6i0Cad "atteries must not e mi-ed and care ta$en that fumesfrom atteries cannot damage other parts.

• Instruments must e $ept at constant temperature and silica gel crystals usedto ensure no moisture is present.

• Ruer hoses and hose assemlies should e lan$ed; stored uncoiled inell )entilated conditions.

• Tyres should e stored )ertically supported at to points.

,ngineers should e aare of the specific storage re7uirements for anye7uipment or materials that they are li$ely to e responsile for.



1).2.4 #ATCH NU'#ER

The term "atch 6umer is often used as an alternati)e for Goods Recei)ed6umer; ecause many companies use this terminology. The &8, should eaare; hoe)er; that the term may e used in another conte-t particularly henitems such as sheet metal; ar metal; ri)ets or similar supplies are recei)ed. This"atch 6umer is gi)en y the manufacturer of the materials and enales them toe traced ac$ to the "atch that as produced at a specific time; using materialssupplied from specific sources and through specific processes. This ould

enale a supplier to trace all materials produced in a particular "atch should anydefect e found in a sample; if e.g. the heat treatment of a sheet metal should esuspect; all metal in that "atch ould need to e chec$ed and possily7uarantined.

1).2.5 AUTHORISED RELEASE DOCU'ENTS

R,+ J &irorthiness 6otice 6o.1% 0 A&R 14

ne of the chec$s hich has to e made as part of the Goods Receipt procedureis to chec$ the &uthorised Release :ocument and to record itDs numer >or GR6o.@"atch 6o. ?; on the Stores 5ael. This is to ensure that from that timeonards; it is possile to lin$ the component@part ac$ to its &uthorised Release

:ocument 0 hen fitted to an aircraft the &uthorised Release :ocument 6o. >oralternati)e? must e recorded into the 5ogoo$ for record purposes.

The need for an &uthorised Release :ocument in the conte-t of aircraftmaintenance is ased on the principle of guaranteeing the reliaility of aircraft.To this end; aircraft and aeronautical parts; must e manufactured; o)erhauled;repaired and maintained to the highest possile standards i.e. in accordance ithstrict re7uirements >"C&RFs and A&RFS? y &ppro)ed rganisations.

The &uthorised Release :ocument is a certification document conforming there7uirements of "C&R su0section &'; A&R 21 and A&R 14. It is pro)ided y anorganisation that holds C&& &ppro)al to supply; o)erhaul; repair; process or testaeronautical parts.

& A&& +orm 1 or &ppro)ed Certificate it a type of &uthorised Release :ocumentand it shall e issued to the consignee for all &ppro)ed parts released underauthority of C&& &ppro)al. ,ach certificate shall e numered serially at the timeof ul$ printing; e-cept as otherise agreed y the C&&. The ording of thecertification shall e as follosJ

MCertified that; unless otherise stated ao)e; the hole of the ao)ementioned parts ha)e een manufactured@o)erhauled@ repaired@modified];tested and inspected in accordance ith the terms of the contract@orderapplicale thereto and conform fully to the standards@specifications 7uotedhereon and the re7uirements of the Ci)il &)iation &uthorityM

SIG6,:.....................................

for and on ehalf of.......................

:&T, ..........................

]:elete here applicale

& Aoint &irorthiness Re7uirements letter dated Septemer 1*'' stated that it isintended to proceed ith )oluntary implementation of the Single +ormat Release:ocument from 1 Aune 1*'*. Copies of this format are shon as o)erleaf. &lso

shon on the page folloing is a copy of an +&& appro)ed +orm '1303.



1).2." #OGUS PARTS

The responsiility for the ensuring that parts are ser)iceale and conform to the:esign rganisation standard; rests ith t:e se/ . The person or organisationincorporating the aeronautical part into the a@c meets their responsiilities yensuring all parts recei)ed come from an &ppro)ed source and are accompaniedith an &uthorised Release :ocument. &irorthiness 6otice 6o. 1% deals iththe &cceptance of &eronautical Parts in detail; highlighting the need to )erifysources of supply. There are pitfalls hich must e guarded against e.g. &/6

1*; headed FThe Prolem of "ogus PartsF gi)es e-amples of ho ogus partsmay come into the system. It also states in &irorthiness 6otice 6o. 1* that a8andatory ccurrence Report 6st e made if a part is suspected as eingogus. &/6 6o. 1!; 3* and *% also deal ith the procurement of aircraft parts?.

There are certain documents that the C&& ill accept as e)idence of originJ

• /hen recei)ed from a manufacturing source appro)ed to A&R021. The &uthorised Release :ocument ill e a A&& +orm 1.

• /hen recei)ed from a manufacturing source appro)ed y the C&& to "C&R &'01 or &'02 or appro)ed y the 6&& of one of the folloing countries. Thedocument ill e a A&& +orm 1.

&ustria 0 &ustro Control

"elgium 0 &dministration :e 5D&eronauti7ue >&&?

+inland 0 6ational "oard of &)iation >6"&?

+rance 0 :irection Generale de 5D&)iation Ci)ile >:G&C?

Germany 0 5uftfahrt "undesamt >5"&?

6etherlands 0 Ri<$slucht)aartdienst >R5:?

6oray 0 Ci)il &)iation &dministration >C&& d?

Seden 0 5uftfarts)er$et >5+(?

Sit=erland 0 +ederal ffice for Ci)il &)iation >+C&?^

• /hen recei)ed from a company appro)ed y the C&& to "C&R &'04 8aterial

8anufacturer; &'0 Process Company; &'0! Test 9ouse; &'0% 8aterial:istriutor or &'01! +astener :istriutor.

• /hen recei)ed y a manufacturing source located in the #S& and appro)edy the +ederal &)iation &dministration >+&&?. The appro)al document ill ean +&& +orm '1304 for ne engines@propellers and +&& +orm '1303 forother ne components.

• /hen recei)ed from a manufacturing source located in Canada andappropriately appro)ed y Transport Canada; the &uthorised Release:ocument ill e a TC& +orm 240%'.

NoteJ Certifications in respect of o)erhaul; repair or similar acti)ities; such asthose issued y organisations appro)ed y the C&& in Group "I; y +&& as

Repair Stations; or in +rance y :G&C as 5icensed /or$shops do not suffice ase)idence of manufacturing origin. /here the organisation has the SupplementaryRating F&irline Spares TransferF added to its Schedule of &ppro)al; &ppro)edCertificates appro)ed and issued in accordance ith the pro)isions of &'01 shalle pro)ided for each transaction and shall e endorsed as follosJ

MThis Certificate co)ers the transfer of airframe; engine or accessory sparesrele)ant to the types of aircraft operated under the &ir perators Certificatehich ha)e een otained from a source acceptale to the C&&M

The only spares eligile for transfer are those detailed in the main aircraft@engineconstructorFs Spare Parts Catalogue and they must ha)e een otained fromC&& appro)ed sources as descried in &irorthiness 6otice 6o.11 or fromsources accepted in riting y the C&&.



1).3 CERTIFICATIONRELEASE PROCEDURES

1).3.1 INTRODUCTION

MA o *s not @*n*s:e nt*, t:e 7+7e/=o/ *s o67,ete. In a oo$ I asrecently reading; one of the characters; a famous eye surgeon rote e)erythingdon in a noteoo$ as a memory aid. She then daily transferred her notes to hercomputer. /hen as$ed hy she rote it don; she said; HIf it isnDt in my

noteoo$; it didnDt happen. This is e7ually true for the &ircraft ,ngineer. If it isnDtsigned for; it hasnDt een done. If aircraft are to e maintained efficiently andsafely; this is an inescapale fact.

8any aircraft engineers consider that doing the or$ is the most important aspectof their <o. In reality the Captain of the aircraft you ha)e <ust or$ed may erelying on a signature on a document to pro)e that the or$ has een done.

1).3.2 CERTIFICATE OF RELEASE TO SER(ICE

Bou are all doing this course so that e)entually you ill e the person signing adocument to release the aircraft to fly. )iously e cannot allo anyone to ethe signatory. Bou ill only e authorised if the company you are or$ing forconsiders you to e competent. The signature releasing the aircraft forms acertificate called a CERTIFICATE OF RELEASE To SER(ICE >CRS?. Thecertificate may e for or$ on a Aumo Aet ith 4 plus passengers; or ano)erhaul of a ra$e unit. In each case; an appropriately authorised engineer illha)e to sign for the or$. If the or$ is on an a)ionic system or component; theauthorised engineer ill e "2 appro)ed. If more than one engineer has eenin)ol)ed in the or$K each one ill sign for the or$ done; so that a numer ofsignatures may e re7uired.

It is important at this point to emphasise that the CRS is the importantcertification for the or$. It releases the or$ to ser)ice. &ll aircraft engineers arealloed to sign for or$ they ha)e completed. They must do so in order that the

or$ is Hseen to e completed. nly appro)ed engineers are alloed to issueCertificates of Release to Ser)ice. The ill normally ha)e a personalauthorisation stamp issued y the organisation. This stamp is used e)ery time aCRS is issued.

1).3.3 CRS STATE'ENT ;WHAT DOES A SIGNATURE SIGNIFY<

The ording on the certificate ill )ary dependent on hat it is eing used for. If itis used for maintenance or$ in a A&R 14 appro)ed organisations the ordingill eJ

Ce/t*@*es t:+t t:e =o/ s7e*@*e ee7t +s ot:e/=*se s7e*@*e =+s +//*eot *n +o/+ne =*t: AR 145 +n *n /es7et to t:e =o/ t:e+*//+@t+*//+@t o67onent *s ons*e/e /e+- @o/ /e,e+se to se/*e.

The to forms of authorisation for components on the pre)ious pages eachcontain a form of CRS. In the case of the A&& +orm one the ording is in loc$s14 and 1. In the case of the +&& '13; the ording is in loc$s 14 and 1*. Ineach case the certificate is signed and authorised y an appropriate person.

In the #E; & Certificate of Release to Ser)ice >CRS? is re7uired folloing anyo)erhaul; repair; replacement; modification; mandatory inspection or scheduledmaintenance inspection to an aircraft or any part of the aircraft or such of itse7uipment as is necessary for the airorthiness of the aircraft. There are certaine-ceptions hich ill e dealt ith later; ut generally spea$ing; hat it means is

that an appropriately authorised person must certify that any or$ carried out onan aircraft or aircraft part has een done correctly.



There ha)e een many incidents in recent years of aircraft accidents or nearaccidents caused ecause or$ has not een carried out correctly. The prolemis that the CRS statement highlighted on the pre)ious page simply says that theor$ has een carried out in accordance ith A&R 14. & more positi)estatement is gi)en in &irorthiness 6otices 6umer 3. This states clearly that thesignatory i.e. the person ho signs a CRS must e satisfied that the or$ haseen carried out correctly ha)ing due regard to the use ofJ

• up to date instructions including manuals; draings; specifications; C&&

mandatory modifications@inspections and company procedures.• recommended tooling and test e7uipment hich is currently calirated here

applicale; and

• a or$ing en)ironment appropriates to the or$ eing carried out.

1).3.4 WHAT IF YOU ARE CERTIFYING ANOTHER PERSONQS WORK

8ost engineers >If they are competent? ill e happy to certify their on or$.8ost of the time; hoe)er; a certifying engineer ill e certifying the or$ ofother engineers. &irorthiness 6otice 3 is 7uite clear in this case. The certifyingengineer assumes responsiility. The certifying engineer must ha)e inspected a

sufficiently representati)e sample of the or$ and the associated documentation;and e satisfied ith the competence of the persons ho ha)e performed theor$. +or comple- tas$s this may re7uire progressi)e or Hstage inspections to ecarried out as the or$ proceeds.



1).4'AINTENANCE PLANNING

The main tas$ of the aircraft maintenance engineer is to produce ser)icealeaircraft to support a flying programme.

1).4.1 TECHNICAL RECORDS

8ost organisations ill ha)e a Technical Records Section or :epartment; hichcompiles and co0ordinates the paperor$ connected ith the maintenance ofaircraft. >If a company is too small to ha)e a separate section to carry out thisfunction; the responsiility for meeting the tas$ rests ith the Chief ,ngineer 0 ithas to e doneL? )iously all engineers in)ol)ed in the maintenance of aircraftmust e aare of the different re7uirements that come under the heading ofpaperor$ and must ensure that they fulfil their role in completing the <o.

The tas$ of Tech. Records can e di)ided into to main functionsJ

• Eeeping aircraft log0oo$s and records up to date and processing theinformation to ensure that all necessary maintenance acti)ities are monitoredand carried out hen due.

• Issuing the necessary instructions and documentation to the Yshop floorF hen

maintenance acti)ities are to e carried out and e)entually to collect in thedocumentation; chec$ it is correct and complete and then to up0date the log0oo$s and records again.

1).4.2 O# NU'#ER

&ircraft maintenance may consist of a single tas$ ta$ing a single person a feminutes. It could also e a comple- aircraft inspection in)ol)ing hundreds ofengineers and ta$ing more than a month. ,ach part of the inspection must eidentified and hen completed; signed for y the engineer completing the tas$. &n aircraft ill come into the hangar for maintenance or$ for a numer ofreasons. It may e due a Scheduled 8aintenance Inspection >S8I?K it may ha)e

a defect; hich re7uires rectification. & time or 5ife e-pired component may needreplacing; a mandatory modification@inspection >&irorthiness :irecti)e? or arecommended Ser)ice "ulletin may ha)e to e carried out; or it may come in toe put into storage; either short or long term.

It is common practice to allocate a Ao 6umer to all <os carried out on aircraft.The numers eing allocated y the hangar management successi)ely to each <o as it arises. The reason for doing this is that all or$ related to a specific <ocan e identified y the Ao 6umer and all the acti)ities can then e co0ordinated under that numer on completion of the <o. /hat sort of things illneed to e identified ith the Ao 6umer

• The first ill e the /RES9,,TS; more of hich in a minute.

• Then the Stores Issue (ouchers on hich ill e recorded all items issued tothat <o i.e. that aircraft >:ifferent organisations may use different methodsand paperor$ for issuing stores; ut the principle ill e the same?.

• The ,ngineersF time sheets ill sho the hours e-pended against each <onumer so that laour costs can e calculated.

• Components@parts sent into or$shops for o)erhaul@repair or out to othercompanies for the same purpose; ill carry the Ao 6umer so that the costsincurred ill e charged to the <o.



The use of a Ao 6umer is; amongst other things; to ensure that costs areapportioned correctly to each <o. 8any engineers feel that such concerns arenot for them. This is a short sighted )ie; ecause generally the costs ha)e to ereco)ered from a customer; or at least used to determine the cost effecti)enessof particular operations. If the costs are not estimated correctly; the engineer mayfind at the end of the month; that there is no cash left to pay agesL

1).4.3 WORKSHEETS

It is essential that records e $ept of all maintenance or$ carried out on aircraft.:efects and rectification can e entered and signed for directly into the logoo$s;ut the logoo$s ould rapidly e filled and difficult to chec$. It is commonpractice to use or$sheets for the folloing reasons.

Consider a S:e,e '+*nten+ne Ins7et*on >S8I?. In this case theor$sheets ill list all the inspections and chec$s to e carried out as part of theS8I. ften they are copies of the maintenance schedule pages ith e-tracolumns in hich the engineers ill sign hen they ha)e completed the <o.Ideally; the or$sheets should contain all rele)ant information to enale theengineer to do the Ao correctly ithout ha)ing to constantly refer to maintenancemanuals. >That is not to say that the engineer ill not need to refer to manualsand; in fact; steps must e ta$en to ensure that manuals are readily a)ailale tohim. Information such as pressures; types of greases to e used; ear limits;can usefully e gi)en on the or$sheets pro)ided they are alays up to date.?The enefits of the or$sheets ill e self0e)ident. The engineer has thedetailed re7uirements at his fingertips; so that he $nos hat he has to doeliminating the ris$ of missing anything. 9e is not constantly handling schedulesand ine)italy ma$ing a mess of them. 9e is ale to sign as he completes eachitem so that records are up to date.

&s defects are found during the inspection; or if the aircraft comes in ith adefect; the defect is entered onto a Continuation or Rectification /or$sheet; i.e. alan$ sheet ith columns for defects; rectification or$ and signatures.8andatory 8odifications; Inspections; Ser)ice "ulletins; or any other or$

re7uired ill e entered on continuation or$sheets also. /hen the or$ iscompleted; the engineer and super)isor or 5icensed ,ngineer if re7uired; illsign to this effect.

1).4.4 WORKPACKS

/hen completed; the or$sheets are then filed in the /RE P&CE. This illnormally e a file containing all of the paperor$ for that particular <o. &ll of the/or$ Pac$s ill e $ept together as part of an &ircraft +ile and held in TechnicalRecords. It is treated as part of the aircraft logoo$. & logoo$ ,ntry ill ha)e toe made on completion of the or$; hich ill refer; here necessary; to the/or$ Pac$ y a Ao 6umer. & reference note ill state here the /or$ Pac$ it

is held i.e. the name and address of the company.

Typical uses of a or$sheet are shon o)erleaf.

1).4.5 PLANNING

Prior to carrying out an inspection; the Planning :epartment ill pro)ide adocument pac$ containing all of the tas$ cards associated ith the inspection;plus any other documents re7uired. This ill e made into a or$ pac$ that illalso contain a list of the documents contained in the pac$. The 8aintenanceControl :epartment ill audit the documents to ensure the pac$ is complete.The pac$age ill then e sent to the technical or$ area concerned.



This or$sheet shos a typical page from a ramp chec$ or$sheet for a "ritish &irays "oeing %4%. The or$sheet page shon is page 1 of ' pages.

The folloing or$sheet is from (irgin &tlantic and shos a completed +light8anagement System tas$ and the associated CRS.



1).5 'AINTENANCE INSPECTION

1).5.1 INTRODUCTION

The aircraft need to e regularly maintained in order to $eep them airorthy. It isa mandatory re7uirement that all aircraft registered in the #nited Eingdom muste maintained in accordance ith an appro)ed maintenance schedule and anyassociated maintenance programme necessary to support the schedule.

"efore aircraft are issued ith a Type Certificate for a ne aircraft; the aircraftConstructor@8anufacturer is re7uired to pro)ide manuals necessary for themaintenance; o)erhaul and repair of aircraft. The manufacturer should alsospecify the recommended periodic inspections and li)es of components. Thisdocument is called a 8aintenance Schedule. The aircraft operator has also toproduce a maintenance scheduled ased on the manufacturers schedule. Theoperators schedule must e appro)ed y the C&&. The manufacturers scheduledoes not ta$e into consideration the ay the operator ill use the aircraft. Itshould e noted that 8anufacturersF recommendations must e ta$en intoaccount hen compiling a maintenance schedule for appro)al y the C&&.

The complete maintenance schedule is ro$en don into a series of le)els; thehighest eing the longest inter)al of time and the most e-tensi)e or$. It shoulde noted that there is ne)er a definiti)e series of inspections for any aircraft. Themanufacturer ill recommend the inter)als for an inspection. These ill notalays e suitale for the operator of the aircraft. The folloing ill gi)e anindication for a typical aircraftJ

• '+o/ C:e 0 This is carried out at appro-imately 1; flying hours or fi)eyears of a)erage use. The time ta$en for this inspection ill eappro-imately 2 to 3 days. It ill usually in)ol)e a thorough strip0don ithremo)al and o)erhaul of ma<or components. The aircraft painted surface ille stripped to allo for thorough surface inspection and the aircraft ill erepainted

• Inte/6e*+te C:e 0 This is carried out at inter)als of 40 hours and theaircraft ill e out of ser)ice for aout * days.

• Se/*e :e 0 :one at inter)als of ' 0 3 hours and ill ta$e from 1to 2 days or si- months of a)erage use

• R+67 C:e 0 This is done at inter)als from 12 to hours and illnormally e done o)ernight

1).5.2 PLANNING THE 'AINTENANCE SCHEDULE

,ach maintenance schedule should ta$e into accountJ the aircraft en)ironment;en route facilities pro)ided y the operator at each ase; fre7uency of landing;hether the aircraft is on short or long haul operations; also type of operation i.e.passenger; cargo or mi-ed. It is o)ious that an operator of a particular aircrafttype may not e in a position to use a 8aintenance Schedule used y anotheroperator. /hen a #E operator has completed his 8aintenance Schedule; it issumitted to the C&& it for appro)al. The C&& may re7uire some changes to emade and ill finally signify its appro)al y issuing an &ppro)al :ocument to the &pplicant. This appro)al document ill normally e in the front of the Schedule.The appro)al document ill specify hen all inspections must e carried out; homust certify it and hat Certification is re7uired. ,ndorsements to the &ppro)al:ocument ill spell out hat e-tensions to inspections may e granted and y

hom. &ny other )ariations to the standard form are also attached asendorsements.



1).5.3 A'END'ENTS TO APPRO(ED 'AINTENANCE SCHEDULES.

The data in an &ppro)ed 8aintenance Schedule shall e amended y theoperator to reflect the emodiment of mandatory and non0mandatorymodifications and inspections; the incorporation of constructorsF andmanufacturersF re7uirements >ulletins etc? and the effects of maintenancee-perience. &mendments shall not normally e incorporated ithout theritten agreement of the C&&. &mendments re7uired y the C&& shall eincorporated in the &ppro)ed 8aintenance Schedule.

There are to types of permissile amendments

CLASS A Those hich are raised y the C&& as a result ofinformation from constructors or operators of a similartype of aircraft.

CLASS # Those hich are raised y the operator as a result ofhis maintenance e-perience. The reasons andsupporting e)idence for Class " amendments must esumitted to the C&& for appro)al eforeincorporation in the 8aintenance Schedule.

The folloing +#R pages gi)e an e-ample of a 8aintenance Schedule &ppro)al :ocument for a typical Tin0,ngine aircraft.

6oteJ This document is for a small aircraft and as issued prior to A&R14 and A&R !!. Conse7uently there are some references hich are notrele)ant to large modern aircraft schedules.



C**, A*+t*on At:o/*t- A*/=o/t:*ness D**s*on

'AINTENANCE SCHEDULE APPRO(AL>AIRCRAFT E9CEEDING 2!3) KG 'TWANOT 'AINTAINED TO #RITISH CI(IL AIRWORTHINESS RE%UIRE'ENTS SECTIONA CHAPTER A$>13

C&& &ppro)al ReferenceJ 8S@ PIP,R P&31@%'

&ircraft &pplicailityJ PIP,R P&3103

perator>s?J +ST,R B,8,6 5I8IT,:

+or the purpose ofJ P#"5IC TR&6SPRT +5BI6G

peratorFs Schedule ReferenceJ S&@6&(&A@1 Issue 2 :ateJ CT",R 1*'4

1 CONDITIONS>GENERAL

1.1 The 8aintenance Schedule identified ao)e >herinafter referred to as YthisScheduleF? is appro)ed y the Ci)il &)iation &uthority >C&&? on the asis thatit prescries the minimum maintenance to e performed on the aircraft tohich this schedule relates. 6othing contained in; or omitted from; thisSchedule asol)es persons employed in implementing the re7uirements;from ensuring that the aircraft is; at all times; maintained in an airorthycondition.

1.2 It is the responsiility of the perator to ensure that recommendations issued

y the &ircraft or ,7uipment 8anufacturers in 8aintenance 8anuals;Recommended 8aintenance Schedules; Ser)ice "ulletins and othertechnical ser)ice information; and rele)ant information issued y the C&&are e)aluated. /here appropriate the perator must initiate 8aintenanceSchedule amendment action ith the C&&.

1.3 In addition to the performance of the maintenance actions prescried in theSchedule; compliance shall also e estalished ith all the appropriatemandatory re7uirements issued y the C&& and y the recognised &irorthiness &uthority of the country of origin of the aircraft. Retirement lifelimitations prescried y the manufacturer shall also e oser)ed; unlessotherise directed y the C&&; normally through the medium of C&&

&irorthiness 6otices or C&& &dditional :irecti)es.1.4 &mendments@alterations to this Schedule shall e appro)ed y the C&&. 6o

change to the Conditions or the ,ndorsements shall e made other than ythe C&&.

1. The re7uirements of this Schedule shall e completed ithin the periodsspecified in the Schedule and in any appropriate ,ndorsements to this8aintenance Schedule &ppro)al :ocument.

1.! The implementation of the re7uirements of this Schedule shall e controlledy such documents and records as ill enale personnel authorised to ma$ecertifications under the &ir 6a)igation rder to ascertain to their satisfactionthat the re7uirements ha)e een complied ith. The prior permission of theSur)eyor0in0Charge; C&& &rea ffice shall e otained efore anymaintenance chec$ is su0di)ided. In implementing the re7uirements of theSchedule; compliance shall; as appropriate; e shon ithJ "ritish Ci)il &irorthiness Re7uirements >"C&R?; Ci)il &ircraft Inspection Proceduresand ith C&& &irorthiness 6otices; ith particular reference to &irorthiness 6otice 6o. 3!.

1.% &ny references to this Schedule in statutory log oo$s and in technicalrecords shall include oth the peratorFs Schedule reference and Issue6umer and the C&& &ppro)al Reference. & copy of this Schedule togetherith a copy of the &ppro)al :ocument shall e made a)ailale to personnelat the locations here the re7uirements of the Schedule are eing

implemented.

2 CONDITIONS>CERTIFICATION



2.1 /or$ carried out on aircraft maintained to this 8aintenance Schedulere7uires the folloing certificationsK

2.1.1 & Certificate of 8aintenance Re)ie.

2.1.2 & Certificate of Release to Ser)ice.

2.2 & Certificate of 8aintenance Re)ie >C8R? must e issued for a period note-ceeding 4 calendar months. The Certificate may e reissued at any timeprior to the e-piry of the last Certificate. The Certificate need not e issuedcoincident ith a Scheduled 8aintenance Inspection.

2.2.1 The signatory of the C8R shall e an engineer Type 5icensed in at leastto categories >e-cluding YF Compasses? appropriate to the aircraft type.

2.3 & Certificate of Release to Ser)ice >CRS? must e issued hene)er ano)erhaul; repair; replacement; modification; mandatory inspection orScheduled 8aintenance Inspection has een carried out; e-cept that heresuch Scheduled 8aintenance Inspections recur at periods not e-ceeding 4flying hours or 2' days elapsed time; no CRS is re7uired.

2.3.1 The signatory for the CRS folloing o)erhaul; repair; replacement;modification; mandatory inspection shall e an engineerlicensed@appro)ed in the trade category appropriate to the tas$

accomplished.

2.3.2 The signatories for the CRS folloing Scheduled 8aintenance Inspectionsshall e engineers appropriately licensed in CategoriesJ

& >&irframe? C >,ngine? R >Radio?

pro)iding that here the Scheduled 8aintenance Inspection has notin)ol)ed tas$s in a particular Category; certification in that category is notre7uired. & signatory in Category YF Compasses is re7uired hene)er aScheduled 8aintenance Inspection specifies a Chec$ Compass Sing.

2.3.3 /here appropriate licensed engineers employed y organisationsappro)ed under "C&R Section &; Chapter &'03; issue the CRS re7uired

y paragraph 2.3.1; such engineers must sign using the &ppro)alReference of the &ppro)ed rganisation.

3 APPRO(AL

3.1 6on0compliance ith any of the Conditions of this &ppro)al :ocument or itFs,ndorsements shall in)alidate the &uthorityFs &ppro)al of this 8aintenanceSchedule.

3.2 This &ppro)al :ocument includes 3 ,ndorsements.

&T :&5T6

for the Ci)il &)iation &uthority

:ateJ 1 A#5B 1*'



ENDORSEMENTS CAA Approval Reference: MS/PIPER PA31/78

No. SetCAAA77/o+,

1 The perator or his contracted 8aintenance rganisation; may )arythe periods prescried y this Schedule pro)ided that such )ariationsare ithin the limits of su0paras >a? to >e? of this endorsement.

(ariations shall e permitted only hen the periods prescried y thisSchedule >or documents in support of this Schedule? cannot ecomplied ith; due to circumstances hich could not reasonaly ha)e

een foreseen y the perator; or y his contracted 8aintenancerganisation.

The decision to )ary any of the prescried periods shall e ta$en onlyy the Chief Inspector@Quality 8anager or person of e7ui)alent statuson ehalf of the perator or his Contracted 8aintenance rganisation.

Particulars of e)ery )ariation so made shall e entered in theappropriate log oo$>s?.

a Ite6s Cont/o,,e - F,-*n0 Ho/s

Period In)ol)ed 8a-imum (ariation of theprescried period

i flying hours or less 1\

ii 8ore than flying hours flying hours Ite6s Cont/o,,e - C+,en+/ T*6e

Period In)ol)ed 8a-imum (ariation of theprescried Period

i 1 Bear or less 1\ or 1 month;hiche)er is the lesser

ii 8ore than 1 year ut not e-ceeding 3 years 2 months

iii 8ore than 3 years 3 months

c Ite6s Cont/o,,e - L+n*n0sC-,es

Period In)ol)ed 8a-imum (ariation of theprescried period

i landings@cycles or less 1\ or 2 landings cycles;hiche)er is the lesser

ii 8ore than landings@cycles landings cycles

d Ite6s Cont/o,,e - 'o/e t:+n One L*6*t

+or items controlled y more than one limit eg items controlledy flying hours and calendar time or flying hours andlandings@cycles; the more restricted limit shall e applied.

e Ite6s A,/e+- Set to CAA T/*+, Etens*on P/o0/+66e

+or an item already su<ect to an agreed C&& trial e-tensionprogramme the trial period may e )aried y a ma-imum of flying hours only; pro)ided that such )ariation is not specificallye-cluded y the agreed trial e-tension programme.

Notes8

1 +or certain piston engine o)erhaul periods the conditions of C&& &irorthiness 6otice 6o. 3 may o)erride the stated conditions.

2 The )ariations permitted ao)e do not apply to J

a Those components for hich an ultimate >scrap? or retirement lifehas een prescried >eg primary structure of components ithlimited fatigue li)es and high energy rotating parts for hichcontainment is not pro)ided?. :etails concerning all items of thisnature are included in the constructors documents or manuals.

Those periods included in the maintenance schedule hich ha)eeen classified as mandatory y the C&& >see C&& &irorthiness

6otice 6o. 3!?.

1.%.'

&: 2%1& 311'4



ENDORSEMENTS (Continued) CAA Approval Reference: MS/PIPER PA31/78

No. SetCAAA77/o+,

2 Para 2.3. of this +orm &: 2%1@2 is herey cancelled and replacedy the folloing statement J

2.3. & Certificate of Release to Ser)ice >CRS? must e issuedhene)er an o)erhaul; repair; replacement; modification;mandatory inspection or Scheduled 8aintenance Inspection>S8I? has een carried out.

6T,J &n S8I is any inspection other than mandatory ;scheduled to recur at periods e-ceeding 2 calendar days andmade for the purpose of ascertaining hether the aircraft remainsairorthy.

1.%.'

3 6otithstanding Para 2.3.2. of this +orm &: 2%1@2 the signatoriesfor the CRS folloing S8I hich recur at periods not e-ceeding flying hours or 6@& days elapsed days may use as analternati)e to para 2.3.2 engineers licensed in categories & &irframes or C ,ngines as appropriate for the tas$ eing

certified. Such engineers shall possess an appropriate type ratedlicence.

1.%.'

&: 2%1& 2!''



1).5.4 CONDITION 'ONITORING 'AINTENANCE

,arly maintenance schedules in)ol)ed fi-ed component li)es and routinestrip0don policies. These ha)e gi)en ay to ne techni7ues ecause they areno longer cost effecti)e or appropriate to the ne design philosophy of modernaircraft. The older methods ere ased on H+/ T*6e or On Con*t*on.

There are no three internationally recognised PRI'ARY 'AINTENANCEPROCESSES

• H+/ T*6e *s + 7/eent+t*e 7/oess in hich deterioration of a componentis restricted y maintenance actions carried out at periods relating to time inser)ice. The periods may e ased on calendar time; landings or flying hours.The maintenance actions normally include ser)icing; full or partial o)erhaul; orreplacement; according to schedule instructions; so that the item may continuein ser)ice for a further time period.

• On Con*t*on *s +,so + 7/eent+t*e 7/oess in hich an item is inspectedor tested at specified periods. The inspection or test may re)eal that the itemmay need further ser)icing or replacement. The main purpose of on conditionmaintenance is that the item is remo)ed efore it fails in ser)ice.

• Con*t*on 'on*to/*n0 has e)ol)ed as M& Primary maintenance process inhich data on the hole population of the items in ser)ice is analysed toindicate hether some allocation of technical resources is re7uired. It is 6T apre)entati)e process; conditioning monitoring maintenance allos failures arealloed to occur; and relies upon analysis of operating0e-perience informationto indicate the need for appropriate action.M & further point to note is that failureof condition monitoring items does not ha)e a direct ad)erse effect on operatingsafety. Condition monitoring is not a separate acti)ity; ut a complete processhich cannot e separated from the complete maintenance programme.8a-imum use can e made of the condition monitoring process hich includesstatistical reliaility element action hen it is applied to aircraft meeting thefolloing criteriaJ

1. 8odern multi0engine; transport category aircraft hich include safeguardsagainst the complete loss of function of a system. These safeguards arepro)ided either y acti)e redundancy or stand0ye redundancy in the designof the aircraft or system. In acti)e redundancy; all the redundant items areoperating simultaneously and share the tas$. If one item fails; the tas$ isshared amongst the remaining items. In stand0ye redundancy; only onesystem is functioning at a timeK if failure occurs; it is necessary to select thestandye system.

2. &ircraft for hich the initial scheduled maintenance programme has eenspecified y a 8aintenance Re)ie "oard and to hich maintenancesteering group >8SG? logic analysis has een applied. ,-amples include the

"oeing %4%; 5oc$heed 5111; 8c:onnell :ouglas :C1.+or aircraft not co)ered y these criteria; the statistical reliaility element may eapplied for the purpose of monitoring system or component performance; utmay not e prescried as the primary maintenance process. To use a statistical0reliaility element of a programme effecti)ely; + @,eet 6*n*66 o@ @*e +*//+@t=o, no/6+,,- e neess+/-. This means that some operators of the ao)eide0ody aircraft ould not e ale to use such a programme.

&s a programme; Condition 8onitoring 8aintenance is the formalised applicationof the T9R,, maintenance processes i.e. 9ard Time; n Condition andCondition 8onitoring to specific items as specified in the schedule. The $ey factorin its use eing the introduction of aircraft emodying failure tolerant designs.



1).5.4.1 T-7es o@ '+*nten+ne At**t-

The three types of maintenance acti)ity used areJ

1. 8aintenance applied at specific times regardless of condition at the time. Themaintenance acti)ity may e periodic o)erhaul; change of parts; reor$;cleaning; caliration; lurication or some other recognised action. Theseresult from hard time re7uirements.

2. Periodic e-aminations; mostly at specific times; ut sometimes on an

opportunity asis; such as hen an item is remo)ed for access; to determinenot only the e-tent of deterioration ut also that the deterioration is ithinspecified limits. These result from on0condition re7uirements.

3. Condition monitoring uses data on failures as items of MconditionM informationhich are e)aluated to estalish if it is necessary to modify the hard time oron condition elements. +ailure rates are analysed to estalish the need forcorrecti)e actions.

8aintenance of a particular item could ell in)ol)e a comination of all threeprimary maintenance acti)ities. There is no hierarchy of the threeK they areapplied to the )arious items according to the need and feasiility.

1).5.4.2 St+t*st*+, Re,*+*,*t- E,e6ent

The assessment of defect@remo)al@failure rate trend at hich items fail or theproaility of sur)i)al to a gi)en life are; in most cases; used to measure thesuitaility of the primary maintenance process applied to items. The assessmentis made y e-amination of rates of occurrence of e)ents such as in0flight defects;incidents; delays; use of redundancy capaility; engine unscheduled shut0dons;air turnac$s; or other such measures; hich are reported. & practical statisticalreliaility element does not need to e complicated or costly to estalish oroperate. Some operators may e reluctant to adopt such a practice ecause theyelie)e that computer systems are necessary. Computer ased systems may ean ad)antage; ut they are not essential. Enoledge of proaility is usually

implied hen discussing statistical techni7ues. &gain; this is not essential; hereall that is re7uired is elementary data collection; summarising and display. &condition monitoring programme has to asic functions

1. To pro)ide; y means of a statistical reliaility element; a summary of aircraftfleet reliaility; reflecting the effecti)eness of the maintenance eing done.

2. To pro)ide significant and timely technical information y hich impro)ementmay e achie)ed through changes to the maintenance programme or to thepractices for implementing it.

1).5.4.3 D+t+ Co,,et*on

It is normal for the 7uality manager to head a reliaility committee to implementthe Statistical Reliaility programme. 8ethods of data collection should dependon its needs. Suggested data for monitoring aircraft systems are pilot reports;engine un0scheduled shutdons; flight delays and cancellations attriuted tomechanical failures. :ata for component performance could e unscheduledremo)al rates or or$shop reports. Sources of data ould e delay reports; in0flight defect reports; authorised operations ith $non defects; inoperati)ee7uipment le)els compatile ith the minimum e7uipment list >8,5?; flightincidents; air turnac$s; line; hangar and or$shop in)estigations. ther sourcesare reports from on0condition tas$s; airorne integrated data system recordings;ser)ice ulletins and other operators e-perience.



1).5.4.4 St+t*st*+, Re,*+*,*t- 'e+s/e6ent

&lert le)els should e estalished for items controlled y the programme. :atasuch as pilot reports per 1; flying hours; unscheduled remo)al rates per 1;component hours can e statistically analysed y standard process 7uality0control methods. ne e-ample uses an alert le)el of three standard de)iationsao)e the mean. It is not essential to use this type of calculationK a simple factorao)e the mean may e ade7uate; such as defining the alert le)el to e 1.3 timesthe mean le)el. The alert le)el is intended to e an indicator shoing a

deterioration of performance hich must e in)estigated and acted upon.

1).5.5 THE 'AINTENANCE STEERING GROUP ;'SG< APPROACH

The principle ehind the construction of modern aircraft maintenance schedulesis the document produced y the M&ir Transport &ssociationM >&T&? 8aintenanceSteering Group 0 3 Tas$ +orce >8SG03? in 1*'.

1).5.5.1 H*sto/- o@ 'SG

The history of this committee and itFs documents can e traced ac$ to 1*!hen the +ederal &)iation &dministration instigated a reliaility program. Thisprogram as aimed at e-ploiting the increase in propulsion system reliaility

hen ci)il aircraft started to change from piston engines to turine engines. &tthe time there as idespread use of M9ard TimeM component li)es; leading to anineffecti)e and e-pensi)e method of ensuring aircraft safety.

1).5.5.2 T:e 'SG A77/o+:

8SG01 as produced in 1*!' and used to de)elop the "oeing %4% maintenanceschedule. 8SG02 folloed in 1*% and as used for the 5oc$heed 5111 and8c:onnell :ouglas :C01 maintenance programmes. The association of,uropean &irlines de)eloped ,8SG in 1*%2; as an impro)ement to 8SG02. Itas used for the &irus &3 and Concorde maintenance schedules. +inally a <oint team collaorated to produce 8SG03 for the "oeing %% %!% maintenance

programs. This as introduced in 1*' and is the current )ersion.

1).5.5.3 'SG>3

The 8aintenance Steering Group >8SG? lays don a set of rules to e folloedin deciding a maintenance policy for an aircraft and its systems. These rules areased on these rules are ased onJ

a the importance of the component or system

the nature of the anticipated failures hich may occur

c the )isiility of the faults

d the possile correcti)e actions

It isnFt possile to ma$e a set of rules hich specify e)ery re7uirement in ad)anceecause some decisions in the process in)ol)e engineering <udgement ye-perienced staff. In the original 8SG01 8SG02 there as considerale scopefor interpretation of the rules; hich led to different results; depending on thee-perience fed in. ne of the o<ecti)es of 8SG03 as to tighten up thedefinitions used y airline staff and manufacturers so as to lea)e little room foramiguity.



A*//+@t '+*nten+ne P/o0/+6 Dee,o76ent

#oe*n0 !4!

• 1&")>"1 > FAA Inst/- /e,*+*,*t- 7/o0/+6

• 1&"$ > H+noo 6+*nten+ne e+,+t*on +n 7/o0/+6 ee,o76ent

'SG 1

Lo:ee L>1)11 Do0,+s DC>1)

• 1&!) > A*/,*ne '+n@+t/e/ 6+*nten+ne 7,+nn*n0 o6ent

'SG 2

A*/s A3)) #/*t*s: Ae/os7+eAe/os7+t*+,e Cono/e

• 1&!2 > E/o7e+n '+*nten+ne S-ste6 G*e

E'SG

#oe*n0 !5!!"! A*/s A31) Foe/ 1))

#oe*n0 !3!>3)) #oe*n0 !4! 4))

• 1&$) > A*/,*ne '+n@+t/e/ 6+*nten+ne 7/o0/+6 ee,o76ent o6ent

'SG > 3



'+*nten+ne P/o0/+6 Dee,o76ent

P/oe/e A77,*+t*on Wo/*n0 #o*es +n Do6ents

• 8aintenance :esign :ata

• &irline e-perience

• Certification and perational Re7uirement

'SC

'WG1 'WG2 'WG3

'WG4 'WG5 'WG"

'PP

'PD

8R"

8R"

:C

AIRLINE

A'P o/

A'S

KEY

'SC8 '+*nten+ne Stee/*n0 Co66*ttee

'WG8 '+*nten+ne Wo/*n0 G/o7

'PP8 '+*nten+ne P/o0/+6 P/o7os+,

'R#8 '+*nten+ne Re*e= #o+/

'PD8 '+*nten+ne P,+nn*n0 Do6ent

A'P8 A*/,*nes '+*nten+ne P/o0/+6

A'S8 A*/,*nes '+*nten+ne S:e,e



1).5.5.4 I67,e6ent+t*on

The initial or$ of implementing the 8SG process is di)ided into se)eral groupssuch as structures; systems; poerplants; electrical@a)ionics; flightcontrol@hydraulics and =onal inspections. Representati)es of the operators>launch customers?; manufacturers; and regulatory odies >C&&; +&&? comprisethe or$ing groups; ho are super)ised y a steering committee. This committeedefines MspecificsM to direct the groupsK These include a procedures guide hich

descries the fre7uency and nature of aircraft inspection to e used. The or$inggroups are also gi)en a specific time schedule; since this interacts ith thecertification and deli)ery of the ne aircraft.

1).5.5.5 'R# Re7o/t

The final report is termed the 8aintenance Re)ie "oard >8R"? Report. This isproduced y the manufacturer and forms the asic document ith hich theoperators then or$. The regulatory organisations must first appro)e the 8R"Report and this is normally done in stages. nce it is a)ailale the operatorsrite their on schedule from the 8R" Report. The end result should e the &ppro)ed 8aintenance Schedule >&8S? or &irline 8aintenance Program >&8P?.

This is a legal document enforced y the regulatory authority. The 8R" Reportalso co)ers operation of the aircraft and some economic considerations inmaintenance decisions. The le)els of importance for maintenance decisions are>1? technical factors >2? operational factors >3? economic factors. nce produced;the &8S or &8P pro)ides the operators staff ith planning information fornecessary materials; laour and facilities.

1).5." THE 'AINTENANCE SCHEDULE

The 8R" report is the starting point for the operator to prepare its onmaintenance schedule. To this may e added tas$s generated yJ

0 The manufacturers maintenance planning document >8P:?

0 The operators engineering department

0 &ny e-tra certification and maintenance re7uirements from theairorthiness authority >C&&; +&&?

The 8P: may contain tas$s additional to the 8R" report hich arerecommended ut not mandatory. These may include or$ on non0airorthinessitems such as passenger cain appearance.

nce the maintenance schedule is finalised; the plans to implement it egin.These include production of other supporting documents related to the schedule;such as maintenance and training manuals. :iscussions aout the ma$e up ofor$ pac$s ta$e place ith production engineering staff. 8odel or$ cards for

e)ery tas$ may e stored in a computer dataase. &rrangements for supply ofconsumales and spares ha)e to e made. Training and recruitmentprogrammes ha)e to e made ased on estimates of s$ills needed and or$loade-pected. If the aircraft is a significant addition to the e-isting fleet; then hangarspace ill ha)e to e allocated or uilt. It is also )ery li$ely that specialisedaccess and ground e7uipment ill e re7uired. 8any of these items may ha)elead times measured in years.



1).5.! INFOR'ATION IN A TYPICAL SCHEDULE

8any engineers only consider the maintenance schedule contains details of theactual or$ re7uired for each inspection. The folloing information is alsonecessary hen carrying out maintenance or$. The e-amples gi)en are from atypical large aircraft maintenance schedule >"& %4% 4?

3 Inspection 5e)els

The inspection le)els defined are specified to ensure that defects hich couldimpair airorthiness or cause an unacceptale economic penalty if not correctedprior to the ne-t scheduled inspection; are detected.

1.1. W+,>/on Ins7et*on & )isual inspection from the ground; al$ing asclose as necessary to detect o)ious damage; lea$s and otherdiscrepancies. The inspection is performed in the pre)ailing en)ironmentusing a hand torch as re7uired.

1.2. Gene/+, (*s+, Ins7et*on 0 & )isual inspection to detect o)iousdamage; lea$s and other discrepancies. & particular )ieing location maye specified; if not; normally accomplished from the ground. & certifyingengineer may re7uire the aircraft to e placed under co)er and additionallighting or access e pro)ided if thought necessary to perform an ade7uate

inspection of a suspect condition.1.3. S/e*,,+ne Ins7et*on & )isual inspection in good light of a specific

area to detect damage or discrepancies in structure; system andpoerplant installations and components. Panel; component and liningremo)al; surface position; cleaning and access re7uirements ill especified. & certifying engineer may re7uire additional lighting or accesse7uipment to e pro)ided and ill use inspection aids such as mirrors asre7uired to perform an ade7uate inspection.

1.4. Det+*,e Ins7et*on & thorough )isual inspection in good light of a highlydefined structural detail; system detail; component or location to detectdamage or discrepancies. & certifying engineer may re7uire the remo)al of

e7uipment or soundproofing; may use hand lenses and may re7uire 6:T)alidation as re7uired to perform an ade7uate inspection.

1.. S7e*+, Det+*,e Ins7et*on &n inspection of a specific location or detailusing a 6on :estructi)e Inspection techni7ue to detect a specific type ofdamage or discrepancy.

2. Ins7et*on St+n+/s

2.1. The ord HChec$ is used to descrie a tas$ to ensure that the itemconforms to a prescried standard.

2.2. The ord HInspect is used to descrie a tas$ hich re7uires a <udgement. &s part of each HInspection the certifying ,ngineer shallma$e a <udgement on hether the detail; component; system or area

inspectedJ

Is; at the time of inspection; free from any oser)ed defects li$ely to affectairorthiness.

/ill remain ser)iceale until the ne-t scheduled inspection of that detail;component; system or area.

Is in a condition hich re7uires a report or recording.

2.3. Types of Inspection

2.3.1. Scheduled Inspection This is any inspection specified in the &ppro)ed 8aintenance Schedule >&8S? for an aircraft.

2.3.2. Transit or Ramp Chec$ & routine inspection or Chec$ carried outduring a turnaround or o)er0night; normally in the airport terminalarea.



2.3.3. [onal Inspection & routine inspection of a specified &8S =one>internal@e-ternal? to detect damage; discrepancies and generalcondition as specified in the &8S item.

2.3.4. 9ighlight _Inspection & routine Inspection of an area; system;component or detail specified in the &8S to detect damage;discrepancies and general condition ut re7uiring amplification of thetas$.

3. Aess @o/ +n Etent o@ Ins7et*on

4.1. [onal Inspection3.1.1. The limits of the area to e inspected are defined y =one numer

and the access pro)ided y the specified remo)al of access panelsand components defined y the &8S.

4.2. &ll other Inspections@Chec$s

3.2.1. The area; component; system or detail to e inspected or chec$edis defined in the &8S; or on the associated or$ documents.

4.3. ,-tension of Inspection &rea

3.3.1. /hene)er a defect is found; the area of inspection shall ee-tended as re7uired to ensure that the full e-tent of the defect isidentified.

4.4. Component Remo)al

3.4.1. Remo)al of components is not re7uired for inspection unless sospecified. 9oe)er; nothing shall pre)ent a Certifying ,ngineer fromre7uiring additional access to carry out a detail inspection todetermine the full e-tent of a defect or to in)estigate an indication ofa potential defect.

3.4.2. &ccess and component remo)al re7uirements for a CorrosionProtection Program >CPP? Inspection and su<ect to rules detailed inthe rele)ant section of the &8S.

4. Con*t*ons to e ose/e +n +77/o7/*+te +t*on t+en

4.1. The folloing conditions ill e oser)ed and e)aluated; as appropriate;on all inspections@chec$s and corrected as necessary. &n &8S item maycontain supplementary information to further define a particularinspection re7uirement. The inspection re7uirements of non0scheduledinspections@chec$s ill alays e fully defined.

4.1.1. General

∗ ,-ternal e)idence of damage

∗ :irt or deris li$ely to contaminate or inhiit the proper functioningof a system; retain corrosi)e fluids; cause e-cessi)e ear etc.

∗ "ro$en seals and or foreign odies indicating failure; incorrectmaintenance or unauthorised access

∗ Spillages and accumulations of fluid or ice

∗ structions of drainage or )ent holes or o)erflo orifices

∗ ,)idence of fuel; air or system lea$s; discharges or o)erheating

∗ Correct seating and sealing of assemlies; fairings and panels

∗ Ser)iceaility and security of fasteners; anchor nuts andreceptacles; connections; loc$ing de)ices and electrical onding

∗ 5egiility of notices

∗ &erodynamic CleanlinessJ +it of doors; access panels and fairings.

4..1.2. 8etal Structure



General metal parts including pipes; ducting; tues; rods and le)ers anda)ionic and instrument rac$ing and panels. Seat framing; galley and toiletstructures.

∗ ,)idence of chafing and ear

∗ :istortion; dents; oil0canning; scoring and crac$ing

∗ Pulled or missing ri)ets; olts; scres and fasteners

∗ Condition of fasteners and fastener holes if parts are detached

∗ Separation of structural onding; failure of elds and spot elds∗ struction of drain paths

∗ Corrosion and deterioration of protecti)e treatment

∗ Condition of corrosion inhiiting compounds

4..1.3. Reinforced plastic structural parts; control surfaces; fairing;radomes and ducting

∗ Crac$ing; scoring; crushing; resin cra=ing; de0lamination; crac$ingand ear around fasteners and degradation due to electricaldischarge

∗ +luid contamination

4..1.4. Control System Components∗ Range of mo)ement; friction. &lignment; fouling; oing

∗ Security of attachments; connections and loc$ing de)ices

∗ Condition of fasteners and fastener holes if parts are detached

∗ Security; positioning and condition of electrical onding

∗ CalesJ ,)idence of fraying; $in$ing; ear and flattening; o)er fullrange of mo)ement

4.1.. GeneralJ Transparency; discoloration; cleanliness; crac$ing;cra=ing and de0lamination.

Coc$pitJ )erheating

4.1.!. Ruer; faric and plastic pipes; seals; cale insulation andco)erings

∗ &de7uate clearance in static@dynamic conditions to pre)entchafing contact. 6oteJ for a)ionic cales@ires see 88 &T& 2 foramplification of the re7uirement.

∗ Cuts; chafing; $in$ing; tisting; loss of fle-iility and ade7uate freelength

∗ Contamination y fluids and corrosion inhiiting compounds.



1)." INTERFACE WITH AIRCRAFT OPERATION

1).".1 AIRLINE SCHEDULING

The main tas$ of an airline engineer is to produce ser)iceale aircraft to supportthe flying program of the airline. The or$ schedule is determined largely ycommercial re7uirements; ith alloances made for factors such as cre dutylegislation; airport capacity; competition from other operators and other modes of

transport. Some of the factors; hich must e ta$en into consideration; areJ

1. De6+n P+tte/ns 0 :emand for air transport )aries ith time; as ith manyother goods. There may e daily; ee$ly and annual demands resulting inpea$s at popular times. The competiti)e mar$et in hich most operatorsor$; forces them into trying to meet these pea$s as reasonaly as possiley ma$ing ser)iceale aircraft a)ailale at the pea$ times. &ircraftmaintenance has to e fitted into the spare time not re7uired for commercialacti)ities.

2. Se+son+, E@@ets 0 &ir transport is largely a leisure0oriented industry today.Tra)el demand follos seasonal )ariations. In the 6orthern hemisphere thismeans that there are large differences in aircraft use in the summer and

inter months. perators ill therefore ant to arrange their maintenance sothat hea)y maintenance or$ is carried out in the inter months. There arealso shorter pea$s in demand at times such as "an$ holidays. n a shortertime0scale there are fluctuations in demand for aircraft at morning orafternoon pea$ times fa)oured y usinessmen. These short term cyclesha)e a strong effect on short haul operations and ma$e it difficult foroperators to achie)e a high aircraft use. Summer is normally the usiest timeof the year and operators ill try to minimise routine maintenance in thesummer. This itself may cause prolems due to the maintenance ase noteing fully utilised; resulting in loss of maintenance re)enue.

3. P,* Ho,*+-s 0 "an$ holidays generate high pea$s lasting a fe days.

&ircraft are o)iously needed during these pea$ periods and maintenanceor$ers may need to e compensated for or$ing during these periods.These periods also ma$e the operator )ulnerale to prolems such asindustrial disputes or ad eather during these periods. &ir traffic controllersoften decide to ha)e a pay dispute o)er a an$ holiday.

4. Rote E@@ets

i S:o/t H+, 0 8ost short haul flying is done in the day time and manycountries restrict night flying due to noise prolems. This means that most aircraftill e a)ailale for maintenance at night. 9u and spo$e netor$s ith mainmaintenance ases and out0stations are typical of short haul operations. Shorthaul operations also puts pressure on maintainers to reduce ground time hich

limits fault finding during the day.

ii Lon0 H+, 0 &ircraft may e aay for se)eral days; ut there is usuallyincreased time for maintenance eteen flights.

. D+-s o@ t:e Wee 0 There is usually a pea$ at the eginning of the ee$endas leisure tra)ellers are outnumering usiness tra)ellers. Some days areless usy than others. In the #E the loest demand is on Tuesdays. This isfre7uent enough to ecome part of a maintenance plan.

!. T*6*n0 0 Commercial timing i.e. or$ start times is an importantconsideration and airlines ill try to schedule for this. "usiness tra)el has amorning pea$ and tra)ellers li$e to return home in the e)ening. It is easier to

rememer the timings of regular flights if they occur at hourly inter)als. &irlines also need to fit in ith long haul flights so that the o)erall tra)el timeis reduced.



%. T/n/on 0 &ircraft only earn money hen they are flying so there is muchpressure for them to spend as little time on the ground as possile. +or thisreason; aircraft may operate different routes to ma-imise their utilisation.

'. Con@*0/+t*on o/ Ro,e 0 &irlines )ary seating plans and loading plans to suitthe mar$et. 8ost tour charter firms and other lo fare promotions utilise highdensity seating. +or usiness0class tra)el and lu-ury tra)el; lo densityseating ill e used. Some flights also use different passenger and cargoconfigurations; often oth on the same dec$. )iously if changes arefre7uent; they ill re7uire manpoer to facilitate alterations to seating;furnishings and galleys etc.

1).".2 'AINTENANCE OPPORTUNITIES

8aintenance opportunities ill )ary ith the nature of the operations and themar$et. The est occasions for maintenance areJ

1. S:o/t H+, O7e/+t*ons )ernight maintenance enales most short0termroutine scheduled or$ and some unscheduled or$ to e carried out. 8anyshort haul routes are used for usiness and commuter tra)el so there is lessdemand for ee$end use; so routine or$ hich ta$es longer than o)ernightcan e done then. The 7uieter midee$ period could e used for some

maintenance.2. L+/0e/ S:o/t H+, These operations are normally flon as usy inclusi)e

tour charters hich pea$ in the summer. There is usually time in the interfor ma<or chec$s and other long tas$s.

3. Eono6* S:o/t H+, A*//+@t "y this e mean aircraft hich yield themost profit. They are usually neer aircraft and hence ha)e high depreciation)alues. This means that they are est used at pea$ operation times such asthe summer and maintenance ould therefore e done in the inter.

4. Lon0 H+, O7e/+t*ons The summer period may last se)eral months. It isdesirale to schedule hea)y maintenance acti)ity outside these times.

/ee$end a)ailaility for must e the highest; so there is a long mid0ee$period for maintenance. There may e longer inter)als during long haulaircraft turnrounds. This or$ is not alays done at the home ase. /intermaintenance is again desirale for this type of aircraft. &ircraft ith unusualroutes or performance; such as Concorde or ultra0long range types >5ondonto &ustralia?; may not ha)e the same pea$ patterns as others. 5u-urymar$ets tend to ha)e a ea$ demand in the summer; so maintenance can edone then.

1).".3 'AINTENANCE > IDEAL PRODUCTION RE%UIRE'ENTS

& different set of o<ecti)es from the commercial one pre)iously discussedemerges if aircraft maintenance is e-amined from the engineers standpoint.

• S:e,e =o/ is predictale and regular and therefore or$ may eplanned in ad)ance; often years ahead. If there are alays aircraft undergoingmaintenance; or$ers can e continuously engaged and shift pattern may eset up to ma-imise maintenance. These shift patterns may e set up for a longperiod ith less need for re)ision and industrial agreements. Some facilitiessuch as painting need specialised e7uipment and ays. This represents aconsiderale in)estment hich must e fully utilised. (arious or$shops; suchas heel ays; hydraulic; structures and a)ionic or$shops are normally set upto support the aircraft or$. Sudden pea$ demands for parts should e a)oided.If demand for parts is ell $non in ad)ance then parts needed for routinemaintenance can e ordered and deli)ered in good time.



• Uns:e,e Wo/ This or$ arises due to the complicated nature ofaircraft ith many possiilities for eha)iour outside their design specification.The solution is to ma$e some pro)ision ased on e-perience and data fromother operations.

• A,,o=+,e De@**en- Use 8odern aircraft ha)e considerale redundancyuilt in; in the form of standy components and duplicate@triplicateunits@systems. "y agreement ith the airorthiness authorities >C&&? operatorsmay class some minor defects as alloale deficiencies and defer the defects

to a later date.



1).! %UALITY CONTROL %UALITY ASSURANCE

It is essential and mandatory that aircraft maintenance organisation carry outregular chec$s to ensure that e)erything is eing done correctly. rganisationsthat carry out any maintenance or$ on commercial transport aircraft; or e)enparts to e fitted to these aircraft must e A&R 14 appro)ed. This appro)al ille dealt ith in full in module 1 >5egislation?.

The most important factors concerning the 7uality control concerning

maintenance areJ

• The 7uality assurance must e independent from the or$. It must e carriedout y persons not in)ol)ed ith the tas$s eing chec$ed.

• It must e carried out regularly. ,ach element should e chec$ed at leastonce a year.

• There should normally e an e-ternal audit as ell as internal audits. ,-ternalmeaning someone from a different organisation.

1).!.1 HOW IS %UALITY CHECKED

In most large organisations there ill e a 7uality department. It is theirresponsiility to ensure e)erything ithin the organisation is done correctly. In thecase of aircraft maintenance; this means that the aircraft are maintained correctlyin accordance ith the maintenance schedule and any other mandatoryre7uirements. It also means that the organisation must remain in compliance iththeir A&R 14 appro)al and any other appro)als they hold. They may e atraining organisation or hold appro)als to do aircraft type courses.

The organisation ill ha)e produced )arious documents specifying ho theycomply ith the )arious re7uirements. These documents are called HCompany,-positions or HCompany Procedure 8anuals. In the Company Procedures8anual it ill specify for e-ample the procedure for oo$ing a component into

stores. It ill also detail the indi)idual responsiilities of the stores staff. It illspecify all of the documentation >forms etc.? used y the stores. There ill e aseparate section for each of the main departments of the organisation.

The 7uality department and more specifically the head of the 7uality departmentis responsile for oth the production of the procedure manuals and for chec$ingthat they are complied ith.

1).!.2 E9TERNAL (ERIFICATION

&n e-ternal )erifier ill chec$ at regular inter)als that the company is performingcorrectly. &s ell as these chec$s the A&& or their representati)es ill also carryout chec$s. If the organisation fails any of the inspections; they may lose their

appro)al. This could mean the company is closed don. In most cases thefailures may e minor and correctale. In this case they ould e alloed tocontinue; ut a close atch maintained to chec$ for further prolems.



11. AIRCRAFT CA#LES

The folloing information has een otained from C&&IP 110 &ircraft ,lectricalCales and as such is intended purely as a guide. The leaflet itself pro)idesguidance material on the appro)al and acceptance of aircraft cales and is asedupon C&& information 5eaflet &:@I5@14@102 &ircraft ,lectrical Cales.

The recent ad)ances made in performance of dielectric materials has led to thede)elopment of aircraft cales hich differ significantly from those in ser)ice inolder aircraft types. ,-perience gained to date on the operation of e-istingaircraft cales and on the recent de)elopments; has shon that there are anumer of areas here it is considered general guidance material ould eeneficial.

11.1 APPLICA#LE RE%UIRE'ENTS

11.1.1 AIRWORTHINESS CODES

The applicale airorthiness code ill depend on the type of aircraft in hich thecale is to e installed. This may e "C&R Section :; "C&R Section E; "C&R

Section G or A&R 2 >see 3.1>d??.The folloing list is pro)ided for guidance purposes onlyJ

• "C&R Section :!013 paragraph %.1 0 Cales and &ssociated +ittings and,7uipment

• "C&R Section E!013 paragraph %.1 0 Cales and &ssociated +ittings and,7uipment

• "C&R Section G!014 paragraph %.1 0 Cales and &ssociated +ittings and,7uipment

• A&R 2

2.13* ,7uipment; Systems and Installation

2.133 ,lectrical ,7uipment and Installation

2.13 :istriution System

2.13* ,lectrical System +ire and Smo$e Protection

NOTEJ See also A&R 6P& 2:+01*1 >8iscellaneous ,lectrical Re7uirements?.

11.1.2 DESIGN RESPONSI#ILITY

+or the purpose of the control of design; electrical cales are considered to e anitem of Ze7uipmentD and therefore the re7uirements of "C&R Section &; Chapter

&40' or Section "; Chapter "40! apply. In general; all cales used forinterconnection ithin the airframe and poer plant are classed as ZCont/o,,eIte6sD and chapter 11.1.3 considers this in specific terms.

NOTE8

• The same paragraph numers ill apply for "C&R 23 and "C&R 2* hereapplicale.

See also &irorthiness 6otice 6o. 12 &ppendi- 6o. 32. ,lectrical Cale +ailureand &ppendi- 6o. 42; 8aintenance and re0installation of piped and cales looms.



11.1.3 APPRO(AL OF CA#LES

#CAR Set*on A C:+7te/ A4>$ +n Set*on C:+7te/ #4>$ ;CAP 553CAP554< 7/oe/es

Cale manufacturers see$ing appro)al of their products need to hold appropriateTerms of &ppro)al under an organisational appro)al to "C&R Section &; Chapter &'01.

Controlled items such as aircraft cales may e certified under ZComponentD orZ&ccessoryD &ppro)al procedure. /here a product is idely used; the &ccessory &ppro)al Procedure ill generally e applicale. In this case; the C&& illassess the design in relation to the specification and to the re7uirements of theC&&; hich ill align here)er possile to ZStandardsD hich ha)e een agreed6ationally or Internationally.

& user ho has; or has access to; a design organisation holding appropriateTerms of &ppro)al may elect to employ cales hich they may certify under theDComponents ProcedureD. & :eclaration of :esign and Performance >::P? ille re7uired and this should e related to a design specification controlled eithery the cale manufacturer or the installing :esign &uthority. & 6ational orInternational ZStandardD may also e employed; ut this ill usually need to esupplemented y a :etailed Specification here the ZStandardD related toperformance rather than construction. "C&R Section &; Chapter &40' andSection "40' >see note? does not include a procedure for granting &pplianceRegistration to e7uipment hich is designed and produced under the control ofan o)erseas &irorthiness &uthority >Chapter "40' paragraph .4?. Suchregistrations ha)e een granted in respect of cales and are the e7ui)alent of &ccessory &ppro)al. The C&& does not normally grant &ppro)als againstStandard or Specifications o)er hich it has no control or influence; or heresuch an appro)al could e in conflict ith the interests of another &uthority. &ccessory &ppro)al does not automatically authorise the installation of a product;each application ha)ing to e appro)ed as noted in paragraph 3.4 eloJ

NOTE8 The C&& has re)ised the current Re7uirements of "C&R Section & >C&P4!? at Issue 2* y di)iding the Certification and &ppro)al Procedures into toSections; namelyJ

• Section & >C&P 3?J &irorthiness Procedures here the C&& has PrimaryResponsiility for Type &ppro)al of the product.

• Section " >C&P 4?J &irorthiness Procedures here the C&& :oes 6otha)e Primary Responsiility for Type &ppro)al of the product.

These three documents ill remain concurrent until 3 Aune 1** at hich time"C&R Section & >C&P 4!? at Issue 2* ill e ithdran.

11.1.4 'ODIFICATION REPAIR

Cales used as replacements; or used for medication of an aircraft; should e ofa type appro)ed y the constructor for that particular aircraft type unless analternati)e is selected y an appro)ed :esign &uthority. This selection shouldrecognise the )arious factors detailed in this 5eaflet. This is most readilyachie)ed y otaining a De,+/+t*on o@ Des*0n +n Pe/@o/6+ne ;DDP< fromthe manufacturer if that manufacturer is suitaly C&& appro)ed. The user shouldalso ta$e steps to ensure that the 7uality of cale is satisfactory and the preferredmethod of achie)ing this is y otaining a CAA A77/oe Ce/t*@*+te from themanufacturer.

This release should define a cale y reference to its specification. +or aircraftconstructed o)erseas; the manufacturing sources appro)ed y the aircraftconstructor as satisfactory for his re7uirements for 7uality should e used.



(erification of product 7uality from the &irorthiness &uthority of the country oforigin should e a)ailale and should e used here possile. >&irorthiness6otice 6oDs 11 and 3* should e oser)ed as appropriate?.

It is important to recognise that the certification re7uirements for electricalinstallations and the design standards achie)ed y aircraft constructors ha)ead)anced ith time; especially in relation to fire ha=ards. Conse7uently; it is notcorrect to assume that e)ery cale type in use has a current appro)al for use onall aircraft. +or e-ample; cales ith P(C insulation such as 6y)in; 8I50/0'!>all types?; or "8S 13013; should not e used on aircraft certified ith netechnology cales employing insulation hich is less li$ely to emit no-ious fumes.

#sers ho do not hold an appropriate design appro)al ut ho ne)erthelesssee$ appro)al for or$ under an &&6; ill normally e e-pected to employ caleselected y a :esign &uthority or employ a cale hich has C&& &ccessory &ppro)al; >or an &ppliance Registration from some o)erseas sources?. & list ofcale types hich currently hold &ccessory &ppro)al are included at the end ofthis section; this list is constantly eing updated and should not e used ithoutreference to the Systems and ,7uipment :esign :epartment; Safety RegulationGroup; Gatic$. &ll manufacturers of &ccessory &ppro)ed cale ha)e goodtechnical literature and pro)ide ser)ice support to their customers. It is stressedthat C&& &ppro)al for a cale does not asol)e the user from his responsiility to

ma$e a correct assessment of the product against the intended duty.

It is important to e aare that generalised claims y stoc$ists and others that acale type is Mappro)edM or M7ualifiedM is li$ely to e of little )alue unlesssustantiated y the procedures prescried in this Information 5eaflet. Thus theM&ppro)alM of a cale design y; say; an o)erseas military agency has nosignificance to a #E ci)il user.

11.2CA#LE CLASSIFICATION

5isted elo are the road classifications used for aircraft cales. Regrettaly;there is little International Standardisation of terminology and it should e noted

that the term ZireD is used in the #S& hereas most other countries tal$ ofZcaleD. ther significant differences in terminology are stated here appropriate.

11.2.1 AIRFRA'E CA#LES

Cales designated as M&irframeM; are intended to e sufficiently roust to satisfythe re7uirements of ZpenD airframe iring and the general iring of Poerplants. 9oe)er; in recent years there has een a strong trend toards )ery thininsulation hich is harder and stiffer than insulation such as P(C. Such ZstiffDcales are perfectly satisfactory if the installation is designed to accept them; utthey may )ery ell e 7uite unsuitale for an older airframe design re7uiring; say;fle-ing o)er hinges. It follos that e)en if all the ma<or declared characteristics

such as o)erall diameter and temperature rating are acceptale; the apparentlye7ui)alent cales may still not e interchangeale.

There are to asic methods of applying cale insulation; namely rapping ande-truding. These methods in themsel)es can produce different MhandlingMcharacteristics. In the #S& the term M8edium /eight0InterconnectM may e usedfor &irframe Cales.

11.2.2 INTERCONNECT CA#LES

MInterconnectM is a term adopted y the "SI to designate cales hich may eused in protected areas of iring such as the interconnection of e7uipment ithinrac$s. Such cale ould normally e installed ithin an assemly hich ould

then e positioned into an aircraft. It ould not; therefore; e su<ect to MpullingthroughM and other such stressful e-ercises.



Interconnect cales employ thinner insulation than airframe types; hich sa)eseight and space and increases fle-iility; the latter eing most important herelooms >undles? are re7uired to turn through small radii into electrical connectors.9oe)er; all the constraints gi)en in chapter 11.2.1 for airframe cale also applyhere.

The term M9oo$0upM is commonly used in the #S& to designate cales of thistype and the designation M5ight /eight0InterconnectM may also e applied.

11.2.3 E%UIP'ENT WIRE

This cale; in)arialy $non as MireM; is intended to e used ithin e7uipmentand; therefore; is )ery fle-ile and suitale for soldering. It is not designed foruse as interconnect iring; ut design organisations do; on occasion; select aparticular type for use in protected areas of an airframe. There is a consideralerange of such cales hich )ary in asic construction and performance and theyshould alays e closely defined. In general; the types in aircraft use areproduced y C&& &ppro)ed rganisations ho pro)ide ?CAA Re,e+se? to"ritish Standard G21 or an e7ui)alent specification. Some manufacturers ha)esought M&ccessory &ppro)alM for "S G21 cale and this has een granted; ut itis not a C&& re7uirement that any form of design appro)al e applied to thiscale hen it is used for its intended purpose; >hich is ithin e7uipmentenclosures here the e7uipment itself is su<ect to control?. If follos that it cane manufactured and released y a Supplier; appro)ed to "C&R Section &;chapter &'02. The term ?'o,e W*/e? is sometimes used for this class of calein the #S&.

11.2.4 FIRE RESISTANT CA#LES

This type of cale is re7uired to retain a defined le)el of electrical insulation in thepresence of fire for fi)e minutes; as defined in "C&R Section :; Chapter :102paragraph 1.1%.2 and A&R 1. M+ire ResistantM should not e confused ith ZhightemperatureD and fire resistant types should only e employed here thisproperty is re7uired ecause other characteristics; such as fluid resistance; illusually e poorer than could e e-pected from a non fire resistant hightemperature cale.

11.2.5 FIREPROOF CA#LES

These cales are re7uired to operate for fifteen minutes in a designated fire asdefined in "C&R Section :; Chapter :! paragraph !..1 and A&R 1 and are foruse in designated fire =ones. "C&R Section :; Chapter :!013 paragraph !.!.2and A&R 2.13* define a fire =one. &s for F*/e Res*st+nt types; they shouldonly e used here necessary.

11.2." 'ULTI>CORE SCREENED AND ACKETED CA#LES

&irframe and Interconnect Cales may e supplied in a multi0core form orgenerally up to four cores; the cores eing tisted together. The multi0core maye <ac$eted >sometimes $non as a sheath? or it may e screened and <ac$eted.The screening is usually a raid hich gi)es '\ surface co)erage; utscreening to a higher standard may e used and on replacement of such cales;the standard must not e degraded. The cores are coloured for identification asdefined in "S G23.

11.2.! DATA #US

:ata "us cales are designed to specific re7uirements hich ill not; as a

general principle; allo for replacement y any other type other than thatspecified y the :esign &uthority for the installation. >This re7uirement ill alsoapply to the terminations of such cales?.



11.2.$ IGNITION CA#LES

These cales are used for the transmission of high tension )oltages in othpiston engine and turine engine ignition systems; and are of the single corestranded type suitaly insulated and screened y metal raided sheathing topre)ent interference. These cales ill e e-amined in more detail under ignitionsystems.

11.2.& THER'OCOUPLE CA#LES

These cales are used in high temperature measuring systems employing thethermocouple principle >see chapter ,rrorJ Reference source not found?. Thematerials used are limited and depend on the temperatures eing measured; for <et engine e-haust gas temperature measurement; the internationally acceptedstandard materials are Chromel and &lumel. +or piston engine e-hausttemperature and cylinder head temperature measurement other cominationssuch as Iron @ Constantan and Copper @ Constantan are used.

11.2.1) CO>A9IAL CA#LES

Co0a-ial cales contain to or more separate conductors. The innermostconductor may e solid or stranded copper ire; and may e plain; tinned; sil)er

plated or e)en gold plated. The remaining conductors are in the form of tues;usually of fine raid. The insulation is usually teflon or polyethylene. uterco)erings or <ac$ets ser)e to eatherproof the cales and protect them fromfluids; and mechanical and electrical damage.

Co0a-ial cales ha)e se)eral ad)antages o)er standard cales. +irstly; they areshielded against electrostatic and magnetic fields. &n electrostatic field does note-tend eyond the outer conductor and the magnetic fields due to current flo inthe inner and outer conductors cancel each other out. Secondly; since co0a-ialcales do not radiate; then li$eise they ill not pic$ up any energy or einfluenced y magnetic fields. Thirdly; co0a-ial cales ha)e specific )alues ofKimpedance; capacitance per unit length and attenuation per unit length.

11.3 SPECIFICATION CA#LE TYPE IDENTIFICATION

"ecause of the large numer of specifications hich e-ist for aircraft cales; it isimpractical to list these in this 5eaflet. Significant differences can occur eteencales complying ith the same asic form of re7uirements and e)en ith the"SI ZGD series of standards; there are prolems in attempting to offer guidance oninterchangeaility eteen products. The folloing information has eencomplied to assist in the recognition of the original specifications.

11.3.1 #RITISH STANDARDS SPECIFICATIONS

&ircraft cale specifications are issued in the &erospace G series of "ritishStandards are referenced in the "SI Bear "oo$. The ma<ority of cales used on"ritish uilt aircraft no in ser)ice ill ha)e een produced to such ZGDspecifications; e.g. "S G221 for 8iny)in.

6eer standard are ased upon general re7uirements gi)en in "S G23. &series of Z:etailed StandardsD numered se7uentially from G232 has no eenpulished and these define cale design re7uirements and physicalcharacteristics. The C&& grants &ccessory &ppro)al to cales hich comply iththese standards; ut an additional 8anufacturerDs :etailed Specification; hichdefines the precise construction; ill also e re7uired y the C&&. This may eon a Zcommercial in confidenceD asis.



"S G23 includes a listing of 8anufacturerDs Identification 8ar$s and also a5etter Code for year of manufacture. This information is reproduced at the end ofthis section.

11.3.2 UK 'ILITARY SPECIFICATIONS

Cales produced for the 8: ill include aircraft types hich are identified as,5. or :.,.+.0 Pt . 8ilitary aircraft produced y a ,uropeanconsortium may ha)e their on cale specifications and a typical e-ample is the

Pana)ia pro<ect hich has produced P&6 specifications. These militaryspecifications are mentioned for information and it should e noted that the C&&does not normally )alidate such specifications.

11.3.3 US 'ILITARY SPECIFICATIONS

The designation of #S 8ilitary Specifications for cale is usually 8I50/0.,ach 8I5 specification has a numer of Zslash sheetsD and the re7uirements ofsuch indi)idual sheets can encompass a large range of cales. It is asolutelyessential to $non the full designation of any 8I5 Specification cale and toreplace li$e ith li$e. &s stated pre)iously; C&& &ccessory &ppro)al cannot egranted against 8I5 Specifications and users should e made aare that the use

of such cales may e difficult to <ustify for other than direct replacementpurposes and here the original selection has an appro)al.

11.3.4 CONSTRUCTORQS SPECIFICATION

&ircraft constructors may pulish specifications and some of the most fre7uentlyseen of these areJ0

a? "oeing 0 "8S

? :ouglas 0 "S

c? &irus Industrie 0 &R or &S6,

d? "&C >Concorde? 0 "&S

It has to e emphasised that these cales are appro)ed in relation to the aircrafton hich they are installed y the constructor; i.e. a cale hich is Zappro)edD foruse y on constructor may not necessarily e acceptale to another.

11.3.5 INTERNATIONAL ;INCLUDING EUROPEAN< STANDARDS

The official ody for the standardisation of aircraft e7uipment; including cale; isthe IS >International Standards rganisation?. The "SI contriutes to the or$of the IS ut it has to e said that fe; if any; IS cale standards areemployed y industry. /ithin ,urope; the Society of "ritish &erospaceCompanies >S"&C? or$s in association ith other manufacturers in the

organisation $non as &,C8& > &ssociation ,uropeanne :es Constructeurs :e8ateriel &erospatiale?. &,C8& see$s to promote their on standards and theypulish ,uropean Z6ormesD as ,6 specifications. These ha)e not yet eenidely adopted; at least ithin the #E; ut preliminary specifications may epulished and these are $non as pr,6 Standards. IS and ,6 Standards maye recognised for installation appro)al purposes e-cept that is not usually ithinthe oundaries of the C&& to grant product appro)al against a specification notcontrolled y "SI or a recognised >&ppro)ed? organisation.



11.3." CA#LE 'ANUFACTURERQS SPECIFICATIONS

The C&& ill accept specifications from &ppro)ed rganisations and ill grant;here appropriate; appro)al against such specifications. The organisationcontrolling the specification has to e a Primary Company >"C&R Section &;Chapter &'01? or a suitaly super)ised o)erseas organisation >see "C&R Section"; Chapter "40' paragraph .4?.

11.4CA#LE PERFOR'ANCE

The definition of cale performance has increased in comple-ity and precisionith the reduction of insulation thic$ness and eight. Some of the cales noused for airframe iring ha)e no more than .! inch >.1mm? of insulationthic$ness and thus there is little margin for error in manufacture or in an aircraftinstallation. The operating temperature dictates to a large e-tent the materialsand constructions used; ut installation re7uirements need to e satisfied ydefining properties such as resistance to insulation Zcut0throughD and arasion. Itfollos that cales need to e selected ith care and the factors detailed eloshould e considered in relation to any intended duty.

11.4.1 APPLICATION

)iously; a primary consideration in cale selection is to determine the class ofcale re7uired ithin the classification gi)en. It should e noted that under onegeneric name there may e a range of insulation thic$nesses hich ill eappropriate for &irframe or for Interconnect cale and thus correct identification;y part numer; is particularly important.

11.4.2 TE'PERATURE

The temperature rating of a cale must e defined to permit comparison ith theorst case re7uirements of the application. If follos that the location of a cale;relati)e to hot air ducts and local hot spots such as poer transformers and somefilament lighting; must e $non. Cales ha)e a specific ma-imum continuous

operating temperature; and for many types; this may e achie)ed y anycomination of amient temperature plus temperature rise due to I2R losses.9oe)er; it should e noted; that in general; it is undesirale to contriute more

than a 4°C rise y electrical heating and that operating temperature and installedlife are directly related. The temperature rating of an airframe cale isdetermined y its construction; and ill e classified at one of the folloingtemperaturesJ0

1°C >osolescent cale types?; 13°C; 1°C; 21°C and 2!°C.

Clearly this temperature rating has to e $non hen e)aluating any design

application.



11.4.3 CA#LE SIE

Cale is usually identified y a si=e numer hich appro-imates to the &/G>&merican /ire Gauge? si=e of the conductor. 9oe)er; some cales employ anumer hich refers to the s7uare millimetres of a conductor cross section;hich is a system used e-tensi)ely for commercial cales. The si=e of cale isthe primary determinate of the electrical protection le)el set y the circuit rea$eror fuse; and should ne)er e reduced elo the le)el estalished y proper co0ordination data. 8anufacturers pulish rating data for single cale in free air; and

for undles of three cales in free air. "y study of the short term and continuousratings for a gi)en cale type and si=e; the correct protection can e determined>C&& &irorthiness 6otice 6o.12 &ppendi- 6o.32 should e oser)ed?. Current

rating data usually relates to a temperature rise of 4°C ao)e amient as statedao)e and due alloance must e made for such electrical heating.8anufacturers data ill normally include conductor resistance in ohms per $8 at

2°C and a temperature correction may e necessary if accurate )oltage dropcalculations are necessary.

It should e noted that cale Zsi=eD relates only to the conductor and thus theo)erall diameter and surface finish for a gi)en si=e may )ary significantlyeteen cale types. Such differences in o)erall diameter may ha)e an effect on

cale sealing in connectors and pressure ungs; and also the selection of pre0insulated terminal ends here a dielectric crimp is pro)ided.

11.4.4 (OLTAGE RATING

&ll cales ha)e a rated )oltage and some; such as e7uipment ires; may especified y )oltage. Particular reference should e made to the specified)oltage of any cale here higher than normal potentials may e used; e-ampleseing discharge lamp circuits and indscreen heating.

11.4.5 CURRENT RATING

&merican /ire gauge si=es simply indicate the physical si=e of the cale and

ha)e only limited earing on the current carrying characteristics of the cale. Thecurrent limits or ratings depend on a numer of factors such asJ

• 6umers of cales in a loom.

• &mient temperature.

• :uration current is floing

Such current ratings need to e otained from tales either produced y themanufacturer or included in the maintenance manuals. The current limits in

tales are ased on a conductor temperature increase of 4°C under theconditions specified in the tale. &s such it is not possile to use the limits in

such tales if the amient temperature to hich the cale ill e su<ected is lessthan 4°C elo the ma-imum permitted conductor temperature.

+or e-ampleJ

The ma-imum ser)ice temperature for +epsil is 1*°C.

The ma-imum permitted continuous current in a single strand of ag 2

+epsil is 1* &mps >this ill raise the temperature of the cale y 4°C; in an

an amient temperature ao)e 1°C?.

So the cale cannot e operated ith a 1* amp continuous current in an

amient temperature ao)e 1°C.

If the ma-imum design amient temperature >1°C for +epsil? is continuouslye-ceeded then the current ratings in the tale ill ha)e to e multiplied y EhereJ



E O

/here T is the ma-imum ser)ice temperature of the cale and t is the higheramient temperature.

+or e-ampleJ If it as intended to use +epsil in an amient temperature of 1%°C;the current )alues in the tale ould ha)e to e multiplied yJ

E O O O ⋅ %%

11.4." FLA''A#ILITY TO9ICITY &ll cales are re7uired to ha)e a defined le)el of resistance to urning hene-posed to standard flame tests. In addition to the re7uirements for flammaility;there e-ists ithin "C&RDs A&RDs and +&RDs; general re7uirements relating to theha=ards of smo$e and to-icity. In recent years; greater emphasis has eenplaced upon these characteristics and hilst they are not yet defined in many ci)ilcale specifications; it is generally true that ne cale types ha)e een morethoroughly in)estigated; aleit on an empirical or su<ecti)e asis.

11.4.! WET ARC TRACKING

& re7uirement has no een formulated to assess the Zresistance to failureD of

cales hen su<ected to a comination of insulation damage and fluidcontamination. The propensity of some insulating materials to Ztrac$D has longeen studied in high )oltage systems ut it has no een found necessary;folloing a failure as detailed later in this section.

"S G23 no includes a test to determine resistance to /et &rc Trac$ing >Test6o.42?; and &irorthiness 6otice 6o.12; &ppendi- 6o.32 ill e used to $eepindustry ad)ised for the C&& position on this su<ect.

Trac$ing can also occur under dry conditions and this is eing studied. Thisfailure mode reinforces the need for good cale installation and maintenancepractise.

11.4.$ 'ECHANICAL PROPERTIES

The assessment of cales insulationDs includes the aility to ithstand thepressure of a sharp edge >cut0through?; and for the aility to ithstand scrapingith a defined lade. It is these tests hich figure significantly in assessingairframe cale and hich are the controlled methods of replacing assessment yscraping ith the thum nail. &s noted earlier; differing constructions result inmar$ changed in handling properties especially ith regard to stiffness andZspringinessD. Installation of looms of thin all hard dielectric cale has to ha)eregard to the reluctance of such looms to e ZsetD in position; especially if thesupporting structure is flimsy. It must not; hoe)er; e assumed that thisapparent strength is translated into the aility to ithstand physical ause.

11.4.& FLUID CONTA'INATION

Cales are re7uired to display a defined le)el of resistance to the effects ofcommonly used aircraft fluids ut this is not to say that cales can ithstandcontinuous contamination; hich should e a)oided. & related ha=ard is thatpresented y sealing compounds ecause these may contain agents hich areaggressi)e to cale insulation. If follos that here a ne cale type isintroduced; the compatiility ith such compounds should e chec$ed. ,7ually;the use of a ne fluid on an aircraft; e.g. ne types of hydraulic fluid; should econsidered in relation to the aility of cales to ithstand contamination.Contamination of cales y toilet or galley aste has to e rigorously pre)ented

or corrected as detailed in &irorthiness 6otice 6o.12 &ppendi- 6o.32



11.5CA#LE CONSTRUCTION

11.5.1 CONDUCTORS

+or e7uipment interconnection and airframe cales; the conductors are normallyof the stranded type and are usually made from plated copper. 9oe)er; si=e 24and smaller si=es of conductor ill e of copper alloy ha)ing a higher tensilestrength. +ire resistant cales may also e of copper alloy or copper conductorsthroughout all applicale si=es.

The total conductor consists of plated strands hich are circular in section andhich are laid up into one of a numer of strands forms. &luminium conductorsare also a)ailale for cales of si=e ' and large ut such cales ha)e not eenithout prolems. &ny modification hich in)ol)es con)ersion from copper toaluminium should e classed as Zma<orD and thoroughly in)estigated; especially inregard to termination techni7ues. )iously; Zaluminium calesD ill need to esignificantly larger in cross section than copper for a gi)en electrical load;ecause of the higher electrical resistance of aluminium.

11.5.2 CONDUCTOR PLATING

Plating is employed on copper; copper alloy and aluminium conductors toimpro)e resistance to correction and to assist termination techni7ues. (ery oftenit is the plating hich ill determine the temperature rating of a gi)en cale andthe figures gi)en elo are those idely recognised ithin the #E.

a? Tin plated copper ma-imum continuous temperature 13°C

? Sil)er plated copper ma-imum continuous temperature 2°C

c? 6ic$el plated copper ma-imum continuous temperature 2!°C

d? 6ic$el Clad plated copper ma-imum continuous temperature 2!°C

6ic$el clad copper is used instead of nic$el plate on fire resistant cale to pro)idea thic$er nic$el element.

The temperature figures 7uoted ao)e may ha)e to e )aried donardsecause of limitations imposed y the cale insulation. 9igher figures; notaly

1°C for tin plating; are sometimes 7uoted in the #S& ut performance at suchtemperature; especially in regard to stale crimp resistance and solderaility isthe su<ect of deate; if not dispute. It should e noted that the plating used oncrimped terminal ends must e compatile ith the conductor plating of thecale; and information should e sought from termination manufacturers.

11.5.3 DIELECTRIC 'ATERIALS CA#LE TYPES

It is not practicale to re)ie in these notes; the performance of all of the many

types of cale construction a)ailale e-cept in general terms ,-tensi)e studiesha)e een made; especially in the #S&; in an attempt to determine an optimumcale type. The conclusion dran is that there is not an o)erall est cale andthat all the materials studied ha)e ad)antages and disad)antages. This is littlehelp to a user ho is see$ing to resol)e the conflicting guidance and ad)iceoffered y organisations hich ha)e a $een commercial interest in the decisionsof an intending purchaser. This information 5eaflet is intended to alert people tothe difficulty of ma$ing a sound <udgement in hat has traditionally eenconsidered to e a simple su<ect.



Insulation material is applied to conductors y one of to asic methods;e-trusion and rapping. In general terms; e-trudale materials are ZheatmeltaleD and are not employed for higher temperature applications. It follosthat toards the upper limit of their operating temperature; their mechanicalstrength hen measured y arasion or cut through; can e significantly lessthan that measured at room temperature. &irframe categories of cale usuallyha)e a doule e-trusion hich are not alays of the same material. & doulee-trusion is also claimed to impart Zcrac$ stoppingD 7ualities. Radiation crosslin$ing of processed material is employed on high performance cales and this

eliminates melting; increases strength and allos for thinner all thic$ness.Cales employing such construction perform ell on the "ritish Standard test foret arc trac$ing.

The most commonly used rapped insulation material is Eapton >see 6ote?;hich is the registered trade name to an aromatic polyimide produced y :upont.8any cale manufacturers orld0ide use Eapton; either singly or in cominationith other materials to gi)e a so0called hyrid construction. Single or douletapes are spirally ound o)er the conductor to a defined o)erlap to gi)e there7uired tape thic$nessF at any one point. Eapton is naturally copper colouredand it is usual to apply a top coat to pro)ide a coloured surface hich ill acceptprint and also gi)e added protection to the cale. It follos that it is totally

incorrect to tal$ of Eapton cales ithout further definition. Some constructions;notaly cales made in the #S& to 8I5/'13'1@11; ha)e een the su<ect ofad)erse comment and it is possile that the use of this particular type ill ediscontinued in some en)ironments. This ould not reflect general re<ection ofcales containing Eapton ecause most constructions pro)ide good o)erallperformance including e-cellent mechanical strength; especially the neer higherhyrid types.

6oteJ Eapton is a :upont trademar$.

The process of rapping insulation pro)ides good control of insulation allthic$ness and there are no cale types hich employ only 4 layers of ZEaptonD;gi)ing a total all thic$ness of appro-imately W! inches >W1 mm? and these

are eing employed throughout the aircraft of some recently certified aircrafttypes. The C&& has not granted an &ccessory &ppro)al as Z&irframeD types tosuch cales; these ha)ing een accepted on a ZComponentD asis.

The special case of P(C insulated cales such as 8iny)in >"S G221? asre)ieed earlier in the notes and all P(C cales are no classed asZsolescent 0 unsuitale for ne designsD.



11."CA#LE FAILURE

The folloing types of failure and 7uality faults are amongst those seen in recentyears.

This is not the total list of cale prolems ut it does; perhaps; indicate theimportance of specifying electrical cale of an appropriate type and 7uality. It isthe design intent that the present generation of C&& &ppro)ed cales should lastan aircraft life; ut this ill only e achie)ed if installations are designed and

maintained ith care and cale selection is made such that operating conditions;especially ma-imum temperature; seldom if e)er; approach the specified limitingparameters.

11.".1 WET ARC TRACKING

&irorthiness 6otice 6o.12 &ppendi- 6o.32 has dran the attention of Industryto the prolem of et arc trac$ing of damaged cales su<ected to fluidcontamination. ser)ation of this &ppendi- and the actions of calemanufacturers should resol)e the prolem; ut the greatest need is to ensurethat hot stamp printing is properly controlled. ZInterconnectD and Z,7uipment/iresD should not e hot stamp printed.

11.".2 'INY(IN

Some atches of 8iny)in ha)e in the past shon a tendency to shed the outernylon sheath ecause of splitting along a flo line inad)ertently introduced duringmanufacture. In dry areas of aircraft; replacement of such cale is not a matterof urgency ut if moisture; especially hydraulic fluid; is present then cale muste replaced. In areas hich are e-posed and prone to fluid contamination; suchas undercarriage ays; modifications to introduce a more suitale cale ha)eeen raised on some aircraft types.

11.".3 #'S 13>2$

5arger si=es of this mineral0filled PT+, cale; especially those used on "oeing%%; %2% and %3% aircraft; tend to e-perience complete insulation failure due tolongitudinal splitting of the total dielectric. Replacement y "8S1303 or,+G5&S to "S G222 under modification action is desirale.

11.".4 A#RASION

Some types of cale ha)e shon a tendency to Zear throughD the insulation at apoint here cale rus on the structure. &reas of high )iration induce thisfailure mechanism and it may e supposed that the stiffer construction of somecales tends to produce a greater contact force and transmit )iration here

pre)iously it as damped. Careful cale loom tying and clipping is necessary toalle)iate this prolem >see &irorthiness 6otice 6o.12 &ppendi- 6o.42?.

11.".5 CONDUCTOR KNUCKLING THROUGH

Some earlier cale constructions tended to e-hiit $nuc$ling of conductors hichcould e se)ere enough to penetrate the insulation. This as induced yapplying e-cessi)e pull through forces and care should e ta$en not to put calesunder tension. +,PSI5 to "S G22; hich is no ZosolescentD; re7uiresparticular care in manufacture and installation to a)oid this defect.



11."." RED PLAGUE

Cales ith sil)er plated conductors can e-hiit the aptly named ZRed PlagueD ifthe plating has een damaged and then e-posed to moisture. Conse7uently;sil)er plated conductors are generally unsuitale for use in unpressurised areas.

11.".! GLYCOL FIRES

It is $non that should de0icing fluid contaminate sil)er plated conductors; anelectrical fire can result. &ccordingly; sil)er plated conductors should not eemployed in areas here de0icing fluid can e present.

11.".$ POOR SOLDERA#ILITY

It should e recognised that the 7uality of free tin on plated conductors rapidlyreduce ith time. The replacement of soldered connections during aircraftmaintenance ill proaly re7uire that conductors are ZtinnedD as part of theprocess. The loss of free tin starts as soon as the cale is manufactured andthus prolonged storage should e a)oided.

11.!CAA APPRO(ED CA#LES

n the folloing pages is a list of &ccessory &ppro)ed cales at the date of issueof this information oo$. Information is supplied on the cale types herea)ailale. In all cases; the cales are appro)ed for use in aircraft su<ect tolimitations as specified in the appropriate :eclaration of :esign and Performance>::P?. +or further information contact should e sought ith the manufacturers.



11.!.1 #.I.C.C.

• C+,e to S7e*@*+t*on #S2G233

:escriptionJ &ppro)al Reference ,1412

The cales are single and multi0core airframe and interconnect; multi0coresheathed airframe and interconnect and single and multi0core screened andsheathed types. Conductors and raids are tin plated; the insulation and sheath

eing ,T+, e-truded and irradiated.Temperature rangeJ !° to X 3°C

Si=eJ Single core airframe 2! to 1 &/G

Single core interconnect 2! to 1' &/G

Sheathed and screened and sheathed airframe 104 cores; 2! to 1! &/G

Sheathed and screened and sheathed interconnect 104 cores; 2! to 1! &/G

• C+,e to S7e*@*+t*on E'C "3

:escription J &ppro)al Reference ,134'

The cales are single core or multi0core metsheath; ha)ing conductors of tinnedannealed copper or sil)er plated copper alloy insulated ith e-truded ,T+,.

Temperature rangeJ !°C to X12°C >tinned conductors?

!°C to X1°C >sil)er plated conductors?

Si=eJ Sil)er plated high strength copper alloy conductor si=e 2!and 24 &/G only.

Tinned copper conductor si=e 22 to 12 &/G >8ediumall?.

NOTE8 Thin all cale also a)ailale; intended for internal iring of e7uipment.

Sil)er plated high strength copper alloy conductor 0 si=e 24 &/G only and tinnedcopper conductor si=es 22 to 12 &/G >Thic$ all?.

• C+,e S7e*@*+t*on EC' "5 ;ACT 2")<

:escription &ppro)al Reference ,132'

The cales are single and multi0core airframe and interconnect; multi0coresheathed airframe and interconnect and single and multi0core screened andsheathed types. Conductors and raids are nic$el plated; the insulation andsheath eing a composite of polyamide and PT+,.

Temperature rangeJ !°C to X2!°C

Si=eJ Single core airframe 24 to 12 &/G

Single core interconnect 24 to 1' &/G

Sheathed and screened and sheathed airframe 104 cores; 24 to 1! &/G

Sheathed and screened and sheathed airframe 104 cores; 24 to 1' &/G



• C+,e to S7e*@*+t*on EC'"" ;ACT 15)<

:escription &ppro)al Reference ,13!!3

The cales are single and multi0core airframe and interconnect; multi0coresheathed airframe and interconnect and single and multi0core screened andsheathed types. Conductors and raids are sil)er plated; the insulation andsheath eing a composite of polyamide and PT+,.

Temperature rangeJ !°C to X1°C

Si=eJ Single core airframe 24 to 12 &/G

Single core interconnect 24 to 1' &/G

Sheathed and screened and sheathed airframe 104 cores; 24 to 1! &/G

Sheathed and screened and sheathed interconnect 104 cores; 24 to 1' &/G

• C+,e to S7e*@*+t*on EC' 45

:escriptionJ &ppro)al Reference ,12!

To core compensating cale comprising nic$el chromium nic$el aluminiumconductors; insulated ith layers of +,P coated Eapton tape and PT+, tape;sheathed ith layers of Eapton tape and PT+, tape.

Temperature rangeJ °C to X2!°C

C+,e to S7e*@*+t*on EC' 4!

• :escription J &ppro)al Reference ,122

Thermocouple e-tension cale0tin sheathed flat design ha)ing conductor nic$elchromium and nic$el aluminium insulated ith Eapton@glass fire raid@colouredPT+, tape all sintered. The sheath o)er the flat tin is of Eapton tape andcoloured PT+, tape >sintered?.

Temperature rangeJ °C to X1°C

• C+,e to S7e*@*+t*on EC' "):escriptionJ &ppro)al Reference ,12'*

The cales are single core; ha)ing conductors of nic$el coated copper. Theinsulation is a composite of silicone ruer; 7uart= and PT+,.

Temperature rangeJ 4°C to X2!°C

• C+,e to S7e*@*+t*on EC' 52

:escriptionJ &ppro)al Reference ,123%

The cales are single core; ha)ing conductors of nic$el coated copper. Theinsulation is a composite of silicone ruer; 7uart= and PT+,.

Temperature rangeJ 4°C to X2!°C

• C+,e to S7e*@*+t*on EC' 44 ;KP2")<

:escription J &ppro)al Reference ,12%*

The cales are single core; screened and sheathed and multi0core screened andsheathed ha)ing nic$el plated copper alloy >si=e 24 only? or nic$el plated copperalloy >si=e 24 only? or nic$el plated copper conductors and raids insulated andsheathed here appropriate ith a comination of PT+, and Eapton@+,P tapsare sintered.


Si=esJ Single core 24 to 12 &/G



11.!.2 RISTS WIRE AND CA#LE LTD.

• Po,-*6*e 3)))SS ;oe 1143 +n 1144<

:escriptionJ &ppro)al Reference ,121'

Single core screened and sheathed Eapton insulated cales ith sil)er platedcopper alloy and sil)er plated copper conductors.


• Po,-*6*e 15)) ;oe 114!<:escription &ppro)al Reference ,12%!

Single core Eapton insulated cale ith a top coat of +,P lac7uer ha)ing electrotinned copper conductors.

Temperature rangeJ !°C to X 13°C

Si=eJ 22012 &/G

• Po,-*6*e 2))) ;oe 114$<

:escriptionJ &ppro)al Reference ,12%%

Sil)er plated copper alloy and sil)er plated copper conductors ith EaptonInsulation.

• T-7e "))) +n ")))T

Single core cales si=es 2201 inclusi)e ith sil)er plated copper conductors.

Single core cale si=es 24 and 2! ith sil)er plated copper alloy conductors.

&ll cales insulated ith +,P@Eapton@+,P tape and PT+, tape o)erall.

Tisted single cales >to; three and four? also a)ailale si=es 2!01!.


• T-7e !))) +n !)))T

:escriptionJ &ppro)al Reference ,13'44

Single core cales; si=es 2201 inclusi)e ith nic$el plated copper conductors.

Single core cales; si=e 2! and 24 ith nic$el plated copper alloy conductors.

&ll cales are insulated ith +,P@Eapton@+,P tape and PT+, tape o)erall.

Tisted single cales >to; three and four? also a)ailale; si=es 2!01!.




11.!.3 RAYCHE' LI'ITED

• R+-:e6 T-7e 44

:escriptionJ &ppro)al Reference ,11!23

Sil)er plated high strength copper alloy conductors or tin plated copperconductors. The insulation is made up of radiation cross lin$ed polyolefinpolymer ith a protecti)e sheath of poly)inylidene fluoride.

The folloing part numers are identified ith respecti)e limitationsJ0

44&'1100Colour

44&'1200Colour &irframe Constructions

44&'1400Colour

44&21100Colour

44&21200Colour 5ight &irframe@Interconnect construction

44&21200Colour

44&11100Colour

44&11200Colour Thin all e7uipment ire constructions

44&11400Colour

44&121100Colour

44&121200Colour Screened and sheathed &irframe cale

44&121400Colour

44&111100Colour 44&111200Colour Screened and sheathed e7uipment ire

44&111400Colour

Note8 denote &/G si=e

Temperature rangeJ %°C to X14°C

• R+-:e6 T-7e 55

Sil)er plated high strength copper alloy or tin plated copper or sil)er plated

copper conductors. The insulation is made up of an e-truded radiation crosslin$ed fluoropolymer.

The constructions are types 1 and 2 in single; to; three and four conductors andMmetsheathM )ersions. & cross reference sheet eteen this specification andRaychemDs type ire part numering system is gi)en on the ne-t pageJ



T-7e

Type 1 single0 >si=e?0colour

Type 1 tisted pair00Colours

Type 1 tisted triple00Colours

Type 1 tisted 7uad00Colours

Type 2 single0 >si=e?0colour

Type 2 tisted pair00colours

Type 2 tisted triple00colours

Type 2 tisted 7uad00colours

Type 2 single X screened Xsheathed00colours

Type 2 tisted pair X screen Xsheath00colours

Type 2 tisted triple X screen Xsheath00colours

P+/t N6e/

&'22024]to 10>colour?

&'!22024]to 1@ >colours?

&'!23024]to 10@@

&''13024]to 10@@@

&'%%!024]to 1!0>colour?

&'%%%024]to 2@

&'%%'024]to 20@@

&''14024]to 1!0@@@

&'%44024]to 1!00>sheath colour?

&'%4024]to 1!0@0

&'%4!024]to 1!0@@0

] Si=e 24 has sil)er plated high strength copper alloy conductors. &ll otherconductors under the part numers shon ha)e tin coated copper conductors.




11.!.4 So*ete F*,ote

• Co+*+, +,es8 RG5$CU RG214U RG31"U +n RG142U

:escriptionJ &ppro)al Reference &R44

• L*0:t=e*0:t +,e t-7e KTTP


Sealed lapped tape; tin plated construction.• PTFE *ns,+te 2)) C +,e t-7e


E[4; ,+221* and E[!% >,7uipment ire?

• KPF 2") t-7e 2") C "))( to s7e F9)5)2


• A,6*n*6 +,,o- onto/ +,e to s7e SP545 @o/ A*/@/+6e se

:escriptionJ &ppro)al Reference &R2'3

• E@0,+s t-7e ;"))( 2") C< > #SG222

6ic$el plated copper X PT+, tapes; glass fire tape and glass fire raid coatedith PT+, insulation.

Si=eJ 0 1 &/GJ &ppro)al Reference &R!4'

12 022 &/GJ &ppro)al Reference &R!4*



11.!.5 K+e,=e/e Re*ns:+0en G6:

• T-7es R2)) R2)1 +n R2)2


PT+, insulated ires

• T-7es R1&! R1&$ +n R1&&

:escriptionJ &ppro)al Reference ,1322PT+, insulated ires

• T-7es R1&5 +n R1&"


PT+, insulated ires

• T-7e No. R151YU

:escriptionJ &ppro)al Reference ,12'!

&luminium conductor; insulated +,P0coated polyimide film and raid

11.!." He/ +n S:ne/ AG

• He/ +n S:ne/ AG ;$)144 se/*es<


The cales are a)ailale in types 1 >interconnect? and 2 >airframe? andconsists of sil)er plated high strength copper alloy stranded conductors. Theconductors are insulated ith e-truded radiation cross lin$ed polyolefin andsheathed ith e-truded radiation cross lin$ed modified poly)inylidene 0 fluoride ofthic$ness indi)idually defined for each type.




11.$ CAA O#SOLESCENT CA#LES

The folloing is a list of osolescent cales; i.e. cales only acceptale formaintenance purposes on aircraft originally ired ith such cale types andunsuitale for ne designs.

11.$.1 #.I.C.C

• 8iny)in >::P 9@T,C9@P1*%? ,%**'

• 6y)in >::P 9@T,C9@P1'? ,%**!

• 8iny)in; :uminy)in; Triminy)in and 8iny)inmetsheath ,*1%'

>::P 9@T,C9@P114?

• 8iny)in and 8iny)inmetsheath >::P 9@T,C9@P11? ,'!*1

• :uminy)inmetsheath and Triminy)inmetsheath ,'23'

>::P 9@T,C9@P1*?

• 8etric 8iny)in cales >::P 9@T,C9@P11* and P12? ,11!!

• 6y)in >::P 9@T,C9@P13? ,!3%*

• Tersilsheath >::P /GC@5@/@!!!? ,!411

• #niny)inlarge >::P 9@T,C9@P14? ,!41'

• 8iny)in >::P 9@T,C9@P1? ,42%3

• +le-y)in >::P 9@T,C9@P11? ,42'*

• Cales to spec ,C8 >&E"? ,1234

• Cales to spec ,C81% ,132'4

• Cales to spec ,C84* EPS6 >EP13? ,122%*

11.$.2 Fot:e/0*,, +n H+/e- L*6*te

• Cale to spec F+9E 24D ,123%4

11.$.3 R*sts W*/e +n C+,es Lt

• +le-)in >::P 6o.13? ,!!41

• iny)in >::P 6o.1? ,'3'

11.$.4 So*ete F*,ote

• P&6 !423 and !42 >ETC5? &R1*4

11.$.5 F*,e+

• Types &82; &84 and &8! &R23

• Types +&892; +&894 and +&89! &R412



11.& CA#LE IDENTIFICATION

These mar$s are purely for identification purposes. 6e applications for mar$sshould e made to the "ritish Standards Institution; 2 Par$ Street; 5ondon; /1&2"S. #se of the committee reference &C, ! ill assist "SI in dealing ith thecorrespondence connected ith this list.

11.&.1 'ANUFACTURERSQ IDENTIFICATION 'ARKS

&,I Cales 5td &&

/5 Gore and &ssociates >#E? 5td. &"

"ritish Insulated Callenders Cales 5td. ""

Pirelli General Cale /or$s 5td. CC

Reliance Cords and Cales 5td. ::

RistDs 5td. ,,

:elta ,nfield Cales 5td ++

9uer and Suhner &G GG

The Concordia ,lectric /ire and Cale Co 5td. 99

:a)u /ires and Cales 5td. EE

:uratue and /ire 5td. 55

Ripaults 5td. 66

5ondon ,lectric /ire Co. and SmithDs 5td. PP

Permanoid 5td. QQ

Standard Telephones and Cales 5td. RR

Raychem 5td. SS

Stirlin Cale Co. 5td. TT

+othergill and 9ar)ey 5td; Tygadure :i)ision. ##

(actite /ire Co. 5td. ((

Connollys >"lac$ley? 5td. //

"rand Re- 5td.

Crompton Par$inson BB

Telephone Cales 5td. [[

11.&.2 COUNTRY OF ORIGIN IDENTIFICATION 'ARKS#nited Eingdon G"

Sit=erland C9

+rance +



11.1) IDENTIFICATION OF INSTALLED CA#LES

&ircraft cales are normally mar$ed ith a comination of letters and numers topro)ide the necessary information to identify the cale; the circuit to hich itelongs; the cale si=e; and any additional information necessary to relate it to acircuit diagram or routing chart. Such a code is usually either of the aircraftmanufacturerDs on specification or one de)ised y the &ir Transport &ssociationof &merica under Specification 1 >&T& 1? hich has een accepted as a

standard.The &T& 1 Specification asic coding of a si- position comination of lettersand numers; hich are printed on the outer co)ering of the cale. Theidentification code is normally printed at specified inter)als along the length of thecale. /here printing is not practical the code is printed on non0metallic slee)esand positioned along the cale length.

11.1).1 #ASIC CA#LE CODING SYSTE'

>1? >2? >3? >4? >? >!?

1 , + ! " 22 68S (

Suffi- :ata

Cale Si=e

Cale Segment 5etter

Cale 6umer

Cct. :esignation 5etter

Cct. +unction 5etter

#nit 6umer

Position 1 0 #nit numer; used here components ha)e identical circuits.

Position 2 0 Circuit function letter and circuit designation letter hichindicates circuit function and the associated system.



& 6ot #sed 6 6ot #sed

" 6ot #sed 6ot #sed

C Control Surfaces P :C Poer Supplies Control

:Instruments other than+light; ,ngine Control

Q +uel

, ,ngine Instruments R Radio

+ +light Instruments S Radar

G 5anding Gear T Special ,lectronics

9 &C Systems Pressurisation &nti0icing

# 6ot #sed

I 6ot #sed (:C Poer :C Control of &C generator systems

A,ngine Starting CS:Control

/ /arning

E ,ngine &P# Controls &C Poer Supplies

5 5ighting B 6ot #sed

8 8iscellaneous [ 6ot #sed

Position 3 0 Cale numer; allocated to differentiate eteen cales hichdo not ha)e a common terminal in the same circuit. Generally;contacts of sitches; relays; etc..; are not classified as commonterminals. "eginning ith the numer one; a different numeris gi)en to each cale.

Position 4 0 Cale segment letter; hich identifies the segment of caleeteen to terminals or connections; and differentiateseteen segments of the circuit hen the same cale numer

is used throughout. Segments are lettered in alphaeticalse7uence; e-cluding the letter I and . & different letter is usedfor each of the cale segments ha)ing a common terminal orconnection.

Position 0 Cale si=e.

Position ! 0 Suffi- data; used to indicate the type of cale and to identify itsconnection function. +or e-ample; in the e-ample code 68S (indicates ny)inmetsheath ungrounded cale in a single0phasesystem.

6 ,arth &5 &lumel C6 Constantan

( Single Phase ac C9 Chromel ,C 6ic$el@Copper

&@"@C Three Phase ac C# Copper

NOTE8 +ull details of the cale coding system ill e found in the 8aintenance8anual or /iring :iagram 8anual for the rele)ant aircraft.

Shon elo is an e-ample of &T& 1 Specification coding.



11.1).2 'ANUFACTURERS CODING

&ircraft electrical cales are normally mar$ed ith an identification code asshon in the folloing e-amplesJ

• Period 1*!3 to 8id 1*%DsJ

6y)in 22 " "

Bear of 8anufacture Code 5etter

8anufacturerDs Code 5etter

Cale Si=e

Cale Type 6ame

• Period 8id 1*%Ds to 31st :ecemer 1*%'J

8iny)in G 22

Cale Si=e

Bear of 8anufacture Code 5etter

8anufacturerDs Code 5etter

Country of rigin

Cale Type 6ame

• /ith effect from 1st Aanuary 1*%* the country of origin code for Great "ritain

as changed from G to G-; although the rest of the code remainedunchanged.



"lan$ Page



12. CA#LE INSTALLATIONS

Cale installations in aircraft must e protected from the effects of arasion;mechanical strain; e-cessi)e heat and all aircraft fluids. The looms should; herepossile; e routed aay from such sources of damage. In areas herea)oidance is not possile other steps need to e ta$en.

12.1SUPPORT OF CA#LING

The caling must e ade7uately supported throughout its length; and a sufficientnumer of cale clamps must e pro)ided for each run of cale to ensure that theunsupported lengths ill not )irate unduly; leading to fracture of the conductorsor failure of the insulation or co)ering.

"ends in cale groups or undles should not e less than ' times the outsidediameter of the cale group or undle ; hoe)er; at terminal loc$s; here thecale is suitaly supported at each end of the end; a minimum radius of 3 timesthe outside diameter of the cale ; or cale undle; is normally accepted.

Cales must e fitted and clamped so that no tension ill e applied in anycircumstances of flight; ad<ustment or maintenance; and so that loops or

slac$ness ill not occur in any position here the cales might e caught andstrained y normal mo)ement of person or controls in the aircraft; or duringnormal flying; maintenance or ad<ustment.

/here it is necessary for cale to fle- in normal use; the amount and dispositionof slac$ must e strictly controlled so that the cale is not stressed in thee-tended position; and that the slac$ ill not e fouled chafed; $in$ed or caughton any pro<ection during mo)ement in either direction.

Cales should normally e supported independently of; and ith ma-imumpracticale separation from all fluid and gas carrying pipelines. To pre)entcontamination or saturation of the cales in the e)ent of lea$age; cales shoulde routed ao)e rather than elo li7uid carrying pipelines.

Cales should not e attached to; or alloed to ru against; pipelines containingflammale fluids or gases.

12.2 LACING

5acing is no longer commonly used on aircraft looms; hoe)er it is still idelyused ithin e7uipmentDs. The lacing cord used on aircraft looms as generally1mm diameter p)c co)ered nylon cord. Inside electrical e7uipment; the cord usedis generally thin a-ed linen or fla- tape; as these are less prone to slipping.

St+/t*n0. The to methods commonly used to start lacing are a hipped startand a $notted start.

/hipped start. 9old one end of the cord on the cale and rap aout 4 turnstightly around the cale and o)er the cord. See diagram. /hen the end is ellsecured; hip a further eight turns and ma$e a loc$ stitch. The hipping can econtinued for any distance re7uired to pro)ide protection against chafing.

Enotted start. 8a$e a clo)e hitch around the cale and secure the ends ith areef $not. 8a$e a loc$ stitch and finish normally.

L+*n0 is achie)ed using a running stitch pressed tightly against the cale loomy means of loc$ing $nots or loc$ing stitches formed at regular inter)als along theloom. The running stitches should e $ept in line; parallel to the ires in the caleloom.



F*n*s:*n0. To terminate the lacing; rap the cord four times around the loom;tight against the last loc$ stitch. #sing a separate piece of cord; form a loop andlay it along the loom. /rap eight turns o)er the loop and pass the end of therunning cord through the loop. Pull the loop out y its free ends; thus loc$ing thecord under the last eight turns. Cut off any e-cess cord.

#/+n:*n0. If only one ire ranches from a loom; it should e ranched out ata loc$ stitch ithout any )ariation in the lacing. If a group of ires lea)e the loomat the same point; they should e laced together. &t the re7uired ranchingpoint; ma$e a loc$ stitch; rap si- turns closely together and ma$e another loc$stitch. This hipping ta$es any sideays forces ithout straining the main lacingor separating the ires of the loom. +orm the ires into the re7uired ranchloom; using a $notted start here it lea)es the main loom.

12.3PROTECTING CA#LES

/hen looms pass o)er; or through parts of the airframe; around pieces ofe7uipment; or through fluid contaminated areas; the iring must e protected.The type of protection used depends on circumstances and hat is permitted inthe maintenance manual.

12.3.1 SYNTHETIC RU##ER SLEE(ES

& ide range of synthetic ruer insulating slee)es is a)ailale. They are used ascale mar$ers and to support and insulate a cale at its point of entry into a plugor termination. They are fitted using special three pronged pliers commonlyreferred to as F9ellermanF pliers. There are three si=es of pliers to co)er the rangeof slee)es a)ailale. & luricant called F9ellerineF oil is also a)ailale to assist ingetting the slee)e o)er the cale or termination to e protected.

12.3.1.1 F*tt*n0 P/oess

• 5uricate the prongs of the 9ellerman pliers ith a small 7uantity of9ellerine oil.

• Slip the slee)e o)er the prongs of the pliers.

• Compress the handles of the pliers to e-pand the slee)e. :o no e-pand theslee)e in e-cess of 3\ or it ill split.

• Place the e-panded slee)e in position o)er the cale.

• Release the handles and ithdra the pliers.

• ,nsure the slee)e is in the correct position.

• Remo)e any luricant from the cale; slee)e and pliers.

12.3.2 HEAT SHRINK SLEE(ING

This type of slee)ing is referred to as Thermofit tuing. It is made from e-trudedinsulating material hich has een su<ected to nuclear radiation duringmanufacture. The application of hot air causes the tue to shrin$ to a pre0determined si=e ithout any appreciale loss of length. In its e-panded form; inhich it is supplied; the tues are easily slipped o)er the terminal; cales orirregularly shaped o<ects. n shrin$ing the material forms a tight mechanicalond o)er the item it as placed.

To otain the correct fit; the material selected should ha)e a reco)ered si=e>shrun$? slightly less than the smallest item to e insulated. & range of mouldedparts such as FBF and FTF <unctions and FootsF for connectors is also a)ailale.

The slee)ing is shrun$ using a Thermo Gun or Thermo Pistol.



12.3.2.1 T:e/6o Gn

The Thermo Gun is one de)ice used for heat shrin$ing. It is mains operated andis specially designed for the shrin$age of Thermofit products. It produces hot airfeed through a range of deflector shields. It is ideal for or$shop loommanufacture; hoe)er; due to the e-posed heating elements and motor; theThermo Gun is not suitale for aircraft use. +or aircraft applications Thermofitproducts should e shrun$ ith a Thermo Pistol.

12.3.2.2 T:e/6o P*sto,

This de)ice uses an air supply otained from a special air regulator control o-. & pressure sitch in this regulator cuts out the heating element if air pressurefalls. The heating elements is of the totally enclosed type and is mains operated. & range of heat deflector shields is again a)ailale.

12.3.3 WRAPPING

,frap and Spyrap are forms of e-tensile rapping that can e ound aroundlooms ithout ha)ing to disconnect the cales. It comes in a )ariety of si=es; topro)ide protection for single cales or looms. /hen applied; the rapping needsto e held in place at either end y cale ties.

12.3.4 RU##ER #EADING GRO''ETS

Ruer eading and grommets are used on parts of the airframe to pre)entchafing of cales or looms that may come into contact ith the airframe.

12.3.5 CONDUITS

Conduits are generally used for con)eying cales here there is the possiility ofe-posure to oil; hydraulic fluid or other fluid. Cales may ta$e the form of plastic;fle-ile metal or rigid metal sheaths. /here shielding against signal interferenceis necessary the cales are con)eyed y metal conduits in contact ith metalparts of the aircraft structure to ensure good onding.

12.3." CA#LE SEALS

In pressurised aircraft it is essential for many cales to pass through pressureul$heads ithout a rea$ in them an ithout causing lea$age of cain pressure.This is accomplished y sealing the necessary apertures ith either pressureungs or pressure proof plugs and soc$ets. & pressure ung comprises ahousing; perforated synthetic ruer ung; anti0frictional asher and $nurledclamping nutsK the housing is flanged and threaded; ha)ing a tapered ore toaccept the ung. The holes in the ung )ary in si=e to accommodate cales of)arious diameters; each hole eing sealed y a thin co)ering of synthetic ruerat the smaller diameter end of the ung. The co)ering is pierced y a special toolhen loading the ung ith cales.



The cales are a tight fit in the holes of the ung hich; hen fully loaded andforced into the housing y the clamping nut; is compressed tightly into thehousing around the cales. The anti0friction asher pre)ents damage to the faceof the ung hen the clamping nut is turned. n assemly; holes not occupiedy cales are plunged ith plastic plugs.

In instances here cales Frea$sF are re7uired at a pressure ul$head; thecales at each side of the ul$head are terminated y specially0sealed plug orsoc$et assemlies of a type similar to those shon in the diagram elo.



13. TER'INATING CA#LES

&ll aircraft cales must e terminated at oth ends. The terminations re7uiredill depend on the installation specification. #p to the late 1*Fs aircraft calesere largely soldered. Since that time the main method of terminating caleshas een y FcrimpingF; ith soldering eing retained for use inside e7uipmentFs.

13.1CRI'PED TER'INATIONS

& crimped connection is one in hich a cale conductor is secured ycompression to a termination so that the metals of oth are held together in closecontact. & typical crimp termination has to principal sections; crimping arreland tongue; together ith; in some types; a pre0insulated copper slee)e hichmates ith the crimping arrel at one end and is formed; during the crimpingprocess; so as to grip the cale insulation at the other in order to gi)e a measureof support.

The arrel is designed to fit closely around the cale conductor so that afterpressure has een applied a large numer of points of contact are made. Thepressure is applied ith a hand or hydraulically operated tool fitted ith a die ordies; shaped to gi)e a particular cross0sectional form to the completed <oint.

The precise form of the crimp is determined y such as the si=e and constructionof the conductor; the materials; and the dimensions of the termination. It is;therefore; most important that only the correct type of die and crimping toolshould e used; and that all necessary caliration chec$s ha)e een carried outon the tool.

There are se)eral ad)antages of crimping. They can e listed as follosJ

• :oes not degrade the cale as other <oining methods e.g. soldering.

• Reduces the prolems of corrosion and o-idisation.

• Gi)es a standard le)el of 7uality each time.

• Reduces the time of connection i.e. has a greater ease of production.

• Pro)ides a simpler approach to repetition.

• Simpler to inspect.

Crimped terminations today are supplied y )arious manufactures. The range ofcrimps they supply is e-tensi)e. Reference should alays e made to theinstallation re7uirements. The ma<ority of terminations are usually either Ring;Tag; Spade; +errules or Pins and soc$ets. The pins and soc$ets are for use ithconnecting plugs and soc$ets hilst the other terminations are used ithterminal loc$s.

13.1.1 CRI'PING RING TAG AND SPADE TYPE TER'INATIONS

The principle terminations for cales rated at 3 amp and elo is a pre0insulated connector $non as the P/e>*ns,+te D*+6on G/*7 ;P.I.D.G.<;manufactured y A*//+@t '+/*ne P/ots ;A'P<.

&n earlier uninsulated form of this crimp type as $non as the F:iamond GripF;ut this is rarely seen noadays.

The use of the &8P P.I.:.G. type termination far outeighs all other &8Pterminations. It is also one of the most common forms of ring or tag typeterminations in use on aircraft.

P/e>Ins,+te R*n0 T+0 +n S7+e Conneto/s



Pre0insulated ring tags and spade terminations comprise a cale recei)ing arreland tongue; these oth eing made of tin plated copper. & copper slee)e ispressed o)er the arrel hich in turn is co)ered y a plastic slee)e. ne end ofthe insulated slee)e o)erlaps the arrel. :uring the crimping operation thisportion is compressed o)er the cale insulation in order to pro)ide support to thecale.

The insulation on each PI:G connector is coloured Red; Bello; "lac$ or "lue.The colour of each connector is related to and is an indication of the si=e of theappropriate crimping tool. These in turn may e recognised y similar colouredhandles. The tool si=e is stamped on the tongues of each connector. Thismar$ing also indicates the cale si=es for hich it is suitale.

The si=e of the connector tongues are )aried and as such may e attached to

terminal studs and scres in the ".S.+.; ".&.; #nified and 8etric ranges.P/e>Ins,+te In>L*ne Conneto/s

In0line connectors comprise a to ay recei)ing arrel made of tin plated copper. & copper slee)e is pressed o)er and o)erlaps each end of the arrel. :uring thecrimping operation this portion is compressed o)er the cale insulated in order topro)ide support. The hole of the connector is co)ered y a hard plastic slee)e.This has an indentation miday along its length so as to pro)ide a means oflocating the connector in the crimping tool. The slee)e is again coloured for thepurpose of identifying the appropriate crimping tool.

13.1.1.1 A'P /*67*n0 too,s

There are three different sets of &8P PI:G type crimping tools; hoe)er; theasic design and operation of each set of tools is the same; so the earliest)ersion ill e used for the tool description.



The tools ha)e to sets of crimping <as. & set of +//e, /*67*n0 +=s hichare preset and not ad<ustale; these crimp the conductor inside the conductorrecei)ing arrel of the connector. The second set are the *ns,+t*on 0/*77*n0 +=s hich are ad<ustale y means of ad<usting pins >2 pins in the older styletools; 1 pin in the neer style tools?; these <as crimp the connector to the ireinsulation; forming a cale support. The ad<usting pins can e put in one of threepositions. Position 1 sets the <as to the smallest opening for thin insulation;position 3 sets the <as to their largest opening for thic$ insulation.

The handles are colour coded to match the colour of the insulation on the

appropriate si=e connectors >crimps?. n the neer tools the to handles ha)eto different colours; one to match the colour of the insulation on the hightemperature connectors; the other to match the colour of the insulation on the lotemperature connectors. The handles also incorporate a certi0crimp ratchet. Thisis to ensure completion of the crimping operation.

It should e noted that; once the handles start to close; they must e fully closedefore the tool can e opened again and any or$ remo)ed.

13.1.1.2 Te/6*n+t*n0 + +,e =*t: +n A'P te/6*n+t*on

The doule action hand tools ha)e three insulation ad<ustments. F*/st,- *t *s

neess+/- to ete/6*ne =:*: *ns,+t*on /*67*n0 +st6ent *s neee @o/t:e +,e e*n0 se. The crimping operation must crimp the insulation as ellas the cale.

Proceed as follos.

2. Place oth Insulation Crimping &d<ustment pins in the 6o.3 position.

3. Place terminal or connector in crimping <as of correct tool >ire si=e range isstamped on the tool? so that the terminal arrel tests against the locator.S7uee=e handle until the terminal or connector is held lightly in place.

4. Insert nst/*77e ire into only the insulationgrip portion of terminal or connector slee)e.

. Crimp the terminal or connector.

!. &fter crimp is made; chec$ the insulation supportas follosK 9old on to the terminal or connectorand end the ire ac$ and forth one. Theterminal or connector slee)e should retain itsgrip on the insulation of the cale.

%. If the ire pulls out; set oth Insulationad<ustment pins to the 6o. 2 position and repeattest.

'. If the ire pulls out; set oth Insulation ad<ustment pins to the 6o. 1 positionand repeat test.

*. If the ire still pulls out; something is rong i.e. incorrect or orn tool.



Re6o*n0 t:e +,e *ns,+t*on

9a)ing determined the correct setting for the insulation gripping <as; the irecan no e stripped for the crimping operation. /hen stripping the ire theinsulation should e stripped ac$ until theJ

St/*77e Len0t: #+//e, ,en0t: o@ te/6*n+, o/ onneto/ 132 *n:

o/ #+//e, ,en0t: o@ te/6*n+, o/ onneto/ ) "66

/ire stripping should e completed using stripmaster >or e7ui)alent? semi0automatic ire strippers fitted ith the appropriate set of <as. Aas designed forthe ne thinall cales can e used on cales ith con)entional insulation;hoe)er the con)erse is not true; +=s es*0ne @o/ onent*on+, *ns,+t*on6st not e se on t:*n =+,, +,es; they ill damage the conductors.

9a)ing stripped the insulation from a cale; it should e inspected to ensure thattheJ

,. correct numer of strands remain

+. strands are not damaged

G. insulation is cleanly cut

#nder no circumstances should cales e stripped using manuallyad<usted stripping pliers.

C/*67*n0 t:e te/6*n+t*on onto t:e +,e

The procedure for crimping the terminals or connectors is as follosJ

1. pen crimping <as y s7uee=ing handles of crimping tool until the ratchetreleases. 9andles ill no open automatically.

11. Place terminal in crimping <as so that the terminal tongue goes under thelocator and terminal arrel rests against locator.

12. S7uee=e handles until terminal is held lightly in place. :o not deformterminal. 6ote that once the ratchet is engaged; the handles cannot eopened.

13. Insert stripped ire into terminal arrel.

14. 9old ire in position and complete crimp y s7uee=ing handles until theratchet releases.

1. If the terminal referred to ao)e ere an in0line connector then to crimp theother half of the connector; it should e remo)ed; repositioned and theprocess repeated. If the connector cannot e turned; turn the crimping toolo)er and repeat the process.

1!. Remo)e the or$ from the crimping tool and inspect the termination; loo$ingforJ

&. :eformity of the termination

". Sharp edges on the terminal insulationC. Correct formation of the dot code

:. Correct positioning of the crimp

,. Conductors protruding correct length from arrel

+. Correct numer of strands )isile in conductor

DO NOT end the ire or attempt to pull it from the termination



13.1.1.3 Dot Co*n0

The handles of the crimping tools are colour coded to indicate the correct PI:Gterminals to e used. /hen crimped; the process lea)es a F:otF code on theinsulation arrel to indicate hether the correct crimping tool has een used forthat connector. The F:otF code enales an inspector to confirm that the correcttool has een used; it is not intended as a means of chec$ing for the personcompleting the crimping operation.

The tale elo sets out the relationship of &/G; the &8P PI:G terminals and

the :ot coding for the earliest set of toolsJ

AWG W*/e S*Je Co,o/ Ient*t- [email protected]. Te/6*n+,s

Dot Co*n0

2! 0 22 Small Bello ne dot

22 0 1! Red ne dot 2 lines

1! 0 14 "lue To dots 2 lines

12 0 1 5arge Bello ne dot 2 lines

2! 0 22 >8iny)in? "lac$ To dots

+or crimping thinall or lighteight cales e.g. Eapton EP or Raychem a later;similar set of tools are used. These ha)e smaller insulation crimping dimensions.These tools are also identified y a colour code and the tale elo sets out thesame relationships of &/G ire PI:G terminals and :ot codingJ

W*/e S*Je+.=.0.

Dot Coe H+n,e Co,o/Coe

Te/6*n+, Co,o/

H*0: Te67. Lo= Te67.

24 22 2 dots 1 "lac$ 1 "ron "ron "lac$

2 1 dot 1 Grey 1 Purple Grey or Purple] Purple ith"lac$ stripe

1' 2 dots 1 range 1 "lac$ range range ith"lac$ stripe

1! 1 dot "oth range range range ith"lac$ stripe

14 2 dots 1 /hite 1 "lac$ /hite /hite ith"lac$ stripe

12 1 dot "oth /hite /hite /hite ith"lac$ stripe

1 1 dot "oth "lac$ "lac$ 000000000000000

] :epends on model of tool used.



13.1.1.4 Ins,+t*on Res*st*n0

&8P introduced the latest series of Insulation Resisting P.I.:.G. >T8? Terminalsin aout 1*'%. These are designed to e used ith the neer thinall calesthat are no e-tensi)ely used e.g. Raychem ; "8S 1301 hich is a "oeingcale. The terminals are characterised y the inclusion of coloured stripes on aclear pin$ or lue insulation. The coloured stripe pro)ides an indication of thesi=e of the crimp in relation to the &/G si=e of the cale. There are normallythree stripes on each termination insulation. The tale elo gi)es the &/G

si=e; colour and dot code for this ne range of terminals. ,ngineers must ensurethat the correct range of crimps are used for the appropriate cales designatedfor use.

AWGW*/e S*Je

W*/e S*JeCo,o/St/*7es

Too, H+n,e Ins,. S,eee

o,o/

C/*67*n0Dot Coe

2! "lac$ Bello 1 :ot

24 "lue Bello 1 :ot

22 Green Red 1 :ot

2 Red Red 1 :ot

1' /hite Red 1 :ot

1! "lue "lue 2 :ots

14 Green "lue 2 :ots

12 Bello Bello 1 :ot

1 "ron Bello 1 :ot

13.1.1.5 '+*nten+ne o@ A'P /*67*n0 too,s

In order to ensure that the crimping tool is functioning correctly; one percent ofeach atch of crimped terminations ith a minimum of 2 specimens aresu<ected to Tensile and 8illi)olt drop tests in accordance ith the manufacturersinstructions. & specimen tale shon elo.

Conto/St/+n*n0

EB* ANC+,e s*Je

A'PDe*e

s*Je

Co,o/ o@Ins,+t*on

A'P Too, TestC//entA67s

'(D/o7'+

Tens*,eSt/en0t:Ls. '*n

1*@⋅ ! 22 8ini 22 "5&CE %*1 11 ' 14

1*@⋅ %! 2 2201! R,:4%3'!

%214 % 1*

33@⋅ %! 1' 2201! R,:4%3'!

%21' % 32

4@⋅ %! 1! 2201! R,:4%3'!

%221 % 3'

4@⋅ %! 1! 1!014 "5#,4%3'%

%2421 % 3'

%@⋅ %! 14 1!014 "5#,4%3'%

%2431 ! %

If any of the test specimens fail to pass the performance re7uirements; all theterminations made ith the crimping tool must e 7uarantined and indi)iduallyinspected. The crimping tool must then e remo)ed from ser)ice and the diedimensions chec$ed using a FG@60GF gauge to ensure they fall ithin thelimits specified y the manufacturer. & specimen tale is shon elo.



Too, No. A>'P De*e S*Je A D*6ens*on G D*6ens*on

Go No Go Go No Go

4%3'! 22 0 1! PI:G 1* 11 3

4%3'% 1! 0 14 PI:G 12 12! 4 !

/hen measuring the FGF dimension; the insulation crimping ad<ustment pinsshould e in position 6o. The tool must e closed efore inserting the gauge.

The tool must e ithdran from use if it fails to meet any of the ao)econditions.

Crimping tools in regular ser)ice should e inspected e)ery three months or 1crimping operations; hiche)er comes sooner; to ensure they are in goodor$ing order and that the dies are undamaged and are free of foreign matter.

13.1.1." In,*ne /*67*n0

The procedure for crimping Minline crimpsM or Mutt splicesM is asically the sameas that used for tags or connectors. If the connector cannot e turned o)er tocomplete the second crimping operation; then the tool must e turned o)er; thismay ta$e some practice.

/hen using inline crimps certain points should e notedJ

• ,ach arrel must carry only one cale unless specifically permitted y theairorthiness authority.

• The crimp must e fitted hori=ontally or positioned so that ingress of moistureis not possile.

• &dditional slee)ing is not permitted to achie)e the ao)e.

• ,nsure operating temperatures not e-ceeded.

• Specific appro)al must e otained from the appropriate airorthinessauthority efore using inJ

• Screened cales

• Co0a-ial cales

• 8ulti cored cales

• Cales greater than si=e 1

• Thermocouple cales

• 9( cales >ao)e 2( rms?

• +ire resistance cales in protecti)e =ones

• Totally enclosed cales; that cannot e inspected

• #se of inline is currently restricted to si=e 1 >3&? or smaller.

• 5o temperature connectors must not e crimped on si=e 12 or larger,+G5&S.



• Repair schemes are restricted toJ

• 8inimum distance eteen <oints in one cale is 2ft.

• 6o more than 2 <oints permitted in 1ft.

• 8a-imum <ointsK runs of 2ft 0 3; runs of 2ft 0 ; runs o)er 2ft 0 '.

• n installation here)er possile oser)e the folloingJ

• &ll <oints must e accessile for )isual inspection.

• Aoints should e positioned so as not to touchJ

• ne another

• :ucting

• Straps

• ther features

• Aoints must if possile e positioned on outside of loom.

• &ll fi-ing attachments must e appro)ed.

• Aoints must e staggered. If this is not possile then positi)eseparation must e carried out using insulation or cale clips.

13.1.2 ER'A CRI'PING 'ACHINE

/hilst hand tools such as the &8P PI:G are suitale for most smaller si=ecales; they are of no use for terminating larger cales. +or terminating largercales; un0insulated ring tags are used in con<unction ith a special hydrauliccrimping tool. The tool incorporates a hydraulic ram and hand pump and comesith range of interchangeale crimping dies; a leed hose and to &llen Eeys.

The die set comprises matching upper and loer die sets coded hg to hn forcale si=es a..g. ! to a..g. . These are fitted into the crimping tool using

the &llen $eys pro)ide. Care must e ta$en to ensure matched dies are fitted intothe tool.

The tool is used in much the same manner as any other crimping tool; ith thee-ception that the pump has to e operated se)eral times efore the crimpingoperation is complete. /hen the correct pressure is attained a ratchet operatespre)enting any further increase in pressure.

nce the crimping operation has een completed; the pressure is released yoperating a pressure relief )al)e on the side of the tool. /hen the pressure isreleased the <as open and the crimped cale can e remo)ed for inspection.



13.1.3 CRI'PING OF CONNECTOR PINS SOCKETS

8odern plug and soc$et connections ha)e remo)ale insert pins or soc$etsmade to &merican /ire Gauge specifications. &gain; )arious systems are inuse; and it is not possile to co)er them all on the course. ne typical system incommon use employs the &+ ' crimping tool; and it is this system that ill ee-amined in these notes. &gain; stents +/e e7ete to 6+e t:e6se,esone/s+nt =*t: ot:e/ s-ste6s +n t:e*/ +sso*+te too,*n0.

13.1.3.1 AF$ C/*67*n0 too,

This tool ill normally e supplied ith a changeale turret and is used ith aselection of pin and soc$et type inserts.

"asic tool 8222@101

Turret head T901 or 1&.8222@102

Crimping tool test gauges G12 or 8222@301

"oth tool handles and turret head ody are coloured lue.

8222@101 refers to the asic tool; ithout the turret and is designed for si=e12 up to 22 contacts using 12 0 2! &/G cale.

&s ith the &8P tools; the &+' tool has a doule acting ratchet and cannot eopened ithout completing the crimping operation.

,ight indentor closures are pro)ided; choice is y selector $no.

13.1.3.2 AF$ C/*67*n0 P/oe/e

Sett*n0 7 too, @o/ o7e/+t*on

Tool must e in open position.

Inst+,,+t*on o@ t//et :e+t +sse6,-8

1%. Press trigger to release turret to inde-ing

position.1'. Position turret head onto retainer ring in

tool.

1*. /ith turret head properly seated againstretainer ring; tighten soc$et head scres;using *@!4 in. &llen $ey. The turret shouldinde- ithout inding.



Ine*n0 t:e t//et8

2. Press trigger so that inde-ing turret pops out to inde-ing position.

3. Selector positioner; refer to colour code date plate on side of turret head forcolour of correct positioner.

31. Rotate turret until colour position is in line ith inde- mar$ on top of turrethead.

32. Press in turret until it snaps into loc$ed position.

Sett*n0 t:e Inente/ C,os/e Se,eto/821. Refer to the data plate on the turret head assemly. "elo the ire si=e and

opposite the contact si=e is listed the correct indenter closure numer.

22. Remo)e the spring clip loc$ from the selector $no.

23. Tool must e in the open position hen using the selector.

24. Raise selector $no and rotate to desired selector numer.

2. Replace the spring clip; and the tool is ready for use.

Re7e+t +oe 7/oe/es =:en :+n0*n0 ont+t +n o/ =*/e s*Je

C/*67*n0 7/oe/e

&ssuming the tool has een set correctly and that the correct termination has

een selected.

2!. Strip the cale insulation so that hen the conductors are inserted into thetermination; the insulation is 1@!4M 0 1@32M from the uc$et of the termination.,nsure conductor is )isile in inspection hole of termination.

2%. Insert contact and prepared cale through the indenter opening into the turretpositioner.

2'. S7uee=e handles together until ratchet releases. &llo handle to return tothe open position then remo)e crimped contact and cale.

2*. Inspect crimp for correct formation; and again ensure cale is )isile ininspection hole.

13.1.4 TER'INATING SCREENED CA#LES

Cales hich ha)e a raided outer conductor or screen; such as metsheath areoften used in audio applications. In order to connect this outer conductor; thescreen; to a terminal loc$; connector or another screen a FtailF or Ffly0leadF isused. There are three principal ays of connecting the tail to the screen; theseareJ

• /hipping ith tinned copper ire

• #sing mechanical crimping procedures

• #sing a heat shrin$ solder slee)e

13.1.4.1 W:*77*n0

This method is rarely used today. It calls for a high degree of engineering s$ill.The tail is hipped onto the screen or raid of the cale using thin tinned copperire. &fter hipping the ire is soldered. #nless utmost care is e-ercised;damage to the insulation of the cale is ine)itale.

13.1.4.2 He+t S:/*n+,e So,e/ S,eee

This method employs the use of special slee)es that contain to ands ofsealant and a central and of solder. The slee)e is placed o)er the screen and

stripped end of the fly0lead. 9eat is applied using a Thermo Gun or ThermoPistol hich shrin$s the slee)e and melts the adhesi)e and solder. &gain; utmostcare must e e-ercised if the conductor insulation is not to e damaged.



13.1.4.3 'e:+n*+, C/*67*n0 P/oe/es

& )ariety of mechanical crimping systems are a)ailale for the application of tails.The T:o6+s +n #etts system has een used as an e-ample in these notes.

Inst+,,*n0 t:e *es *n t:e WT!4) too,J

• Insert the stem of upper die into the tool frame.

• Insert the separation spring of the loer die into the upper die opening. Pushup firmly and insert the loer die stem into the hole in the ram.

Inst+,,*n0 t:e onneto/ on s:*e,e +,eJ

• Insert the connector; ith the ground trap facing up; into the nest area of thedie. "e sure to centre the connect.

• Place the ground ire into the ground trap and the shielded cale into theottom of the connector. "e sure to utt the cale <ac$et and ground ireinsulation against the metal connector edge. The ground ire can e-it fromeither direction.

• S7uee=e the tool handles to form the connector around the shield.

• C+t*onJ "e sure that neither the cale outer <ac$et nor the ground ireinsulation is under the metal portion of the connector. This ill o)erload thedies.

'+t:*n0 t:e onneto/ +n *e to t:e +,eJ

• 8easure the diameter of the cale shield using a calirated measuring tool.Rotate the cale in order to locate the ma-imum shield diameter. ,-ert onlylight pressure on the cale to get an accurate measurement.

• +or tisted pair and other non0symmetrical shielded cales; measure the

dimension of the ma<or a-is or the largest idth of the cale.



• #se the M:iameter of ShieldMcolumn in the tale elo tomatch the measurement to thecorrect connector andinstalling die.

D*+6ete/ o@

S:*e,

Conneto/C+t. No.

Coe

D*e C+t. No

G/on W*/eR+n0e

D*e G+0e C+t.No.

>1.2% 0 1.%' mm.? 0 % in.

RSE11R,:

11RSE

11&1 R 2

]24 &/G STRR 1

]22 &/G STR

11&G

>1.' 0 2.2! mm.?%1 0 '* in. 11" 11"G

>2.2* 0 2.4 mm.?* 0 1 in.

RSE21"5#,

21RSE

21C

1 R 2]22 &/G STR

R 1]2 &/G STR

21CG

>2.! 0 3 mm.?11 0 11' in. 21: 21:G

>3.22 0 3.33 mm.?11* 0 131 in. 21, 21,G

>3.3 0 3.!3 mm.?132 0 143 in. 21+ 21+G

>3.!! 0 4.11 mm.?144 0 1!2 in.

RSE31B,55/31RSE

31G 1 R 2]22 &/G STR

R 1 R 2]2 &/G STR

31GG

>4.14 0 4.% mm.?1!3 0 1' in. 319 319G

>4.%2 0 .1 mm.?1'! 0 21 in. 31A 31AG

>.13 0 .'4 mm.?22 0 23 in.

RSE41GR,,641RSE

41E

1 R 2]2 &/G STR

R 1]1' &/G STR

41EG

>.'% 0 !.3 mm.?231 0 2 in. 415 415G

>!.3% 0 !.*' mm.?21 0 2% in. 418 418G

>%.1 0 %.!2 mm.?2%! 0 3 in. 416 416G

C+,e 7/e7+/+t*onJ

NoteJ These connectors should not e usedith multi0conductor shielded cales hoseconductors are solid or stranded onded ire.

• Remo)e the cale <ac$et as re7uired andprepare the shield as shon in the standardmethod illustration.

• C+t*onJ :uring all stripping operations; use

e-treme care to pre)ent nic$ing or cutting ofthe shield or inner conductor insulation. Thiscould result in short circuits.

• /hen the cale inner conductor insulation is)inyl of .1 in. or less thic$ness or Teflon or.1 in. or less thic$ness; use foldac$method 1 or 2 as illustrated.



• /hen the shield is foil or is spiral rapped;use foldac$ method 2.

• /hen using either foldac$ method; e sureto measure the diameter of the shield after itis folded ac$. Refer to the tale for properdie selection.

• G/on =*/e 7/e7+/+t*onJ

• +or a single ground ire; strip the ire %@1! in.>11 mm? and tist the strands together.

• +or to ground ires; strip each ire 1@2 in.>12 mm? and tist the to ires together.

• If hairpinning >hoo$ing? the ground ire isdesired; strip the ire 1@2 in. >12 mm? andend it as shon. #se one die si=e larger.

• C+t*onJ :o not solder dip the ground ire ends.

• C+t*onJ :o not use solid ground ire.

G+0*n0 t:e *esJ

• Install the die set into the /T%4 tool.

• Close the handles of the tool so that the face of the red insert in the loer die <ust touches the face of the upper die. :o not s7uee=e the tool eyond thispoint.

• Select the gage hose catalogue numer corresponds to the die cataloguenumer and insert it from either side of the die into the slots in the upper andloer dies as shon.

• If the gage freely enters until the gage shoulder touches the side of the loerdie; the die is orn eyond limits. If the gage ill not enter ith gentlepressure up to its shoulder; the dies are ithin limits and ill produce goodinstallations.

Intene UseJ/rap around connectors ha)e een designed to ground the shield of single ormultiple conductor shielded cales. It is suggested that the customer e)aluatethe suitaility of these connectors and )erify their performance for the particularapplication.



13.2SOLDERING

Connections inside electronic e7uipment are normally made y soldered <oints.:ue to the increasing reliaility of modern components; failure of solderedconnections is causing an increasing proportion of the total e7uipment failures.

The reliaility of a soldered <oint depends on the condition of the material to e <oined and on the care and s$ill of the operator ma$ing the <oint. Poor <ointscaused y surface o-idisation can e )irtually eliminated y sealed storage

methods and y careful preparation of the materials immediately prior tosoldering.

& high le)el of operator s$ill can only e maintained y regular repetiti)e practiceand y meticulous attention to detail hen ma$ing a <oint.

13.2.1 SOLDERING IRONS

To enale the solder to run freely and to comine ith the surfaces to e <oined;the solder and the surfaces must e at the correct temperature. The normalmethod of applying heat is ith an electrically heated soldering iron. The or$ingend; or it; is made from copper ecause it is a good conductor of heat hich

allos the solder to create a tinned or$ing face. & large numer of different types of soldering irons are in ser)ice use; and it isessential that the correct iron is chosen for a specific tas$.

'+*ns o7e/+te */ons. The &nte- type G24 is one of a large range of generalpurpose mains operated miniature irons. This iron has an 1' att element hichreaches or$ing temperature in aout * secs. The its are interchangealeith four different si=es eing a)ailaleK 3@32 inch; 1@' inch; 3@1! inch and 1@4inch.

Lo= o,t+0e I/ons. Se)eral types e-ist ith operating )oltages of ! )olts; 12)olts and 24 )olts. These irons are used mainly for or$ on printed circuitsoards and transistorised e7uipment and operate from the mains through

electrostatically screened isolating transformers.

He+- t- */ons. Solon *'3@*'4 are to commonly used hea)y duty irons.These irons ha)e either ! att or 24 att elements and ha)e an o)al shape it.They are designed for hea)y duty soldering tas$s and must not e used forprinted circuit or other transistorised or$.

Te67e/+t/e ont/o,,e */ons. Soldering irons used in micro0miniature or$should e temperature controlled here the it temperature is monitored andmaintained stale ithin specified tolerances. Ser)o controlled or Curie effectirons meet this re7uirement.

So,e/ 7ots. +or certain soldering operations; e.g. tinning the ends of <umperleads; the use of a ench mounted solder pots is recommended. & typical potconsists of an electrically heated crucile and a tue hich is tapered so that the

end of a lead inserted into it is guided don and dipped into the molten solder. Insome case a thermostat control and thermometer are incorporated.



#*ts. These are generally detachale and designed in a )ariety of shapes andsi=es to enale selection of the est suited for the <o. "its are manufacturedfrom high grade copper and may e unplated; or plated ith an iron coatingcalled ferroclad. The shan$s are normally chromium plated to protect againstcorrosion; to pre)ent feed0ac$ of solder; and to facilitate remo)al andreplacement. #nplated its re7uire fre7uent dressing ith a file on account ofear; this results )ariations in heat retention capailities. +erroclad >Iron clad?its ear less rapidly and are therefore recommended. Fe//o,+ *ts 6st note ,e+ne =*t: + @*,e; use a damp sponge.

13.2.1.1 C+/e 6+*nten+ne o@ */ons

/hen properly used a soldering iron has a long life. The folloing hints ill helpto achie)e this.

• The it must e $ept clean and tinned at all times.

• &ny o-ides that form on the it should e remo)ed immediately and shoulde retinned immediately.

• :o not o)erheat; it causes the it to pit and o-idise. To pre)ent this the ironshould e sitched off hen not in use; alternati)ely; place on a heat sin$

eteen <os.• ,nsure the leads are not frayed or damaged. If so they can $ill; also ensure

that a hot iron does not come into contact ith the mains lead as a fire ororse can result.

13.2.2 SOLDER

Soft solder is an alloy of tin and lead. It is melted and alloed to flo eteenthe surfaces to e <oined. & fused <oint is formed y an alloying action eteenthe solder and the metal surfaces. The <oint produced is not )ery strongmechanically ut is a good conductor of electricity. The lac$ of strength in asolder <oint means that + 0oo 6e:+n*+, o*nt 6st e @o/6e 7/*o/ to

so,e/*n0.

The most suitale solder for electrical or$ contains !\ tin and 4\ lead;melting at 1*NC. Some solders contain small amounts of antimony or copperand melt eteen 1*NC and 24NC. The soft solder normally used for electricalor$ as supplied at 22 S/G; flu-0cored ire.

Soldered <oints can only e used at temperatures elo 1NC.

13.2.3 FLU9

Soft solder cannot alloy ith a metal if there is any arrier such as oil; grease oro-ide present at the <oint surfaces. These surfaces must e thoroughly cleaned

and a flu- must e used to pre)ent o-ide formation hen ma$ing the <oint. Theflu- used for electronic or$ is a high0grade chemically de)eloped resin. Theresidue is not0corrosi)e; moisture proof and hard. Residue should alays eremo)ed from <oints used at high fre7uencies to pre)ent its dielectric propertiesfrom affecting the circuit.



13.2.4 HEAT SINKS

Some components e.g. transistors are easily damaged y heat and must eprotected during the soldering operation. 9eat sin$s are designed to shunt theheat aay from the soldered <oint; therey protecting components. In use theheat sin$ is clipped to the ire eteen the component as near the <oint aspossile so that heat is asored y the heat sin$ and does not reach thecomponent. 9eat sin$s can also e used here application of heat to; and <oint

is li$ely to melt the solder of ad<acent <oints.

/hen soldering leads to miniature connectors; the connectors should e matedand heat applied for the shortest possile time. The mated connector ill act asa heat sin$ for the one eing soldered and help to pre)ent damage to theinsulation.

& thermal shunt can e made y seating copper ars into the <as of acrocodile clip.

13.2.5 ANTI>WICKING TOOL

/ic$ing is a term used in connection ith the soldering of leads; and it refers tothe seepage of solder along the conductor. /ic$ing should not e alloed toe-tend eneath the insulation co)ering of a lead and it is therefore recommendedthat an anti0ic$ing tool e used. See diagram elo.

The <as of the tool are of the re)erse0spring type; and the shape of the tipspermits gripping of the lead insulation and the e-posed part of the lead; so thatduring soldering the tips ser)e as a heat sin$.



13.2." SOLDERING PROCEDURE

Good soldering is a s$ill hich can e de)eloped only y repetiti)e practice. Theasic methods is as follosJ

3. Clean and tin the or$ing face of the soldering iron it. &llo iron; time toreach the correct or$ing transistorised circuits.

31. The surfaces to e soldered must e clean; right and free from o-ides.Some cales ha)e a protecti)e a- coating hich must e remo)ed ith asuitale sol)ent.

32. 8a$e a firm mechanical connection and apply heat sin$s to protect sensiti)ecomponents.

33. &pply the tinned iron to the surfaces to e <oined. &pply the flu-0cored solderto the or$; not to the iron. If the or$ is sufficiently hot the solder ill readilymelt and run into the <oint.

34. /hen enough solder has een applied the iron should e remo)ed and the <oint alloed to cool naturally. It is important that the solder solidifies eforethe surfaces are alloed to mo)e.

3. Remo)e any surplus flu- from the <oint and remo)e the heat sin$s.

13.2.! INSPECTION OF SOLDERED OINTS

n completion of a soldering operation; <oints should e )isually inspected;paying particular attention to the points elo. /here necessary a magnifyingde)ice e usedJ

• &ll <oints should present a neat; right and shiny appearance ith ell formedsolder films or fillets feathering out to a thin edge.

• The 7uantity of solder should not e e-cessi)e. If the contour of theconductor and <oint configuration cannot e seen then there is e-cessi)esolder.

• The ends of leads protruding through holes should not e-tend e-cessi)elyfrom their mounting lands.



• There should e no e)idence of flu- residue at points of contact; or of pittingand holes in solder. Aoints ith such defects should e carefully inspected toensure that no mo)ement of the conductor occurs hen the <oint is proed;and to determine hether the defects are only surface imperfections.

• There should e no e)idence of cold <oints as indicated y a dull; chal$y orcrystallised fla$y surface of the solder.

• There should e no solder spi$es.

• Insulated leads should e chec$ed to ensure their insulation is at thespecified distance from the termination and that the insulation is notdamaged.

13.2.$ CO''ON SOLDERING FAULTS

&ll the faults descried are the result of careless or$ing methods or lac$ of s$ill.

• D/- o*nts. This is the name gi)en to a <oint hen the solder fails to alloyith the or$ surfaces. & dry <oint usually has a dull rough surface and caneasily e ro$en y slight pressure ith the lade of a scredri)er. It illcause a high resistance connections possily intermittent; hich may e )erydifficult to trace after the e7uipment has een returned to ser)ice. The most

common causes of dry <oints are grease; dirt and mo)ing the <oint efore thesolder has solidified.

• Ins,+t*on D+6+0e. The insulation on a ire or component can e damagedy the application of heat for too long a period. & short circuit can then ecaused y )iration or mo)ement of the e-posed conductor hich couldresult in an e7uipment fire. The damaged insulation must e replaced or asuitale insulating slee)e fitted.

• Eess*e So,e/ . The fle-iility of a stranded cale can e destroyed yalloing e-cess solder to run along the strands from a <oint. The rigid endcould fracture under )iration conditions causing an open circuit and total

loss of the circuit function. ,-cessi)e solder on the uc$ets of miniatureconnections or the conducting strips of a printed circuit oard ill reduce thespacing eteen ad<acent connections and may allo arcing to occur at highaltitudes.

• S7*es. & spi$e or tail of solder pro<ecting from a <oint can e caused yusing an iron hich is not at its full or$ing temperature or hich has a dirtyit. These spi$es may cause corona discharge to ta$e place at high )oltagesand affect the operation of the circuit. In e-treme cases the tail may touch anad<acent connection under )iration conditions and cause a short circuit

• Eess F,. +lu- residue left on or near a <oint ill act as a dielectric at highfre7uencies and may affect the circuit. It can e remo)ed y gentle pressure

ith a small scredri)er lade.



13.2.& DESOLDERING 'ETHODS

13.2.&.1 W**n0 'et:o

This method utilises a length of flu- impregnated raid formed to resemle alamp ic$; hich is applied to a solder <oint eteen the solder and the heatedit of the soldering iron. The comination of heat; molten solder and spaces inthe ic$ creates a capillary action; hich causes the solder to e dran into the

ic$. In the asence of commercially a)ailale ic$s; lengths of stranded iresuch as onding straps made e used.

This method should only e used to remo)e solder from surface <oints

13.2.&.2 So,e/ Se/s

In this method de0soldering is carried out y draing molten solder from a <ointthrough a hollo it. The hollo it may form part of a separate suction de0soldering tool hich is used in con<unction ith a con)entional soldering iron; or itmay form part of a specially designed iron.

In a separate de0soldering tool the suction is generated y depressing a springloaded piston inside the tool ody; and then releasing it hen the solder at the <oint has melted. The solder is dran into a chamer from hich it can eimmediately e<ected y pressing the piston again. In simpler types the suction isgenerated y a s7uee=e ul of stiff ruer connected to the hollo it )ia asmall collecting chamer.

13.2.*.2.1peration

3!. Press the reset $no to engage the release latch.

3%. &pply heat to the <oint. 9old the tip firmly against the <oint at an angle of 4degrees. :o no press into the <oint. :amage may result.

3'. &s soon as the solder has melted; press the operating trigger. Remo)e theiron as soon as the )acuum stro$e has ended.

3*. Reset the tool immediately to e<ect the solder from the tip.

13.2.*.2.2Cleaning

&fter se)eral cycles of operation the tool should e cleaned out. This in)ol)esunscreing the teflon tip and remo)ing the solder deposits from inside the tue

and tip if necessary.



13.2.&.3 Hot A*/ et 6et:o

This method uses a controlled flo ofhot air and permits melting of a solder <oint ithout physical contact. Theheated air may e supplied throughthe hollo it of a specially designedtool; or; in some commerciallya)ailale solder e-tractor irons; it may

also e selected as a mode ofoperation.

These de)ices allo the rapid remo)al of solder from tags or printed circuit oardcomponent mounting points. This can greatly simplify the ser)icing tas$s andreduce the possiility of damage caused y the application of e-cessi)e heatduring component replacement.

13.2.&.4 He+te/ #,o 6et:o

The heater loc$ method is intended for the simultaneous de0soldering of anumer of connections; e.g. the connection of dual0in0line circuit pac$ages. Thede0soldering it ta$e the form of a small copper loc$ hich is normally arranged

in the manner shon in the diagram elo.

The pins are of tuular steel and are precision ra=ed in the loc$ at a spacinghich corresponds oth to the rele)ant hole spacing of the oard and to the pin

configuration of the pac$age. The loc$ should e applied to connections on thecircuit side of a oard and ith the aid of tee=ers the pac$age should e gentlypulled from the oard. Residual solder should e remo)ed from the holes y asolder e-tractor iron efore remounting the original pac$age or a replacement.

,-treme care should e e-ercised hen using heater loc$s of all types. Theyact as heat reser)oirs and hen applied to a oard considerale heat can etransmitted into the ase material.



13.3 WIRE>WRAPPING OF ELECTRICAL CONNECTIONS

The ire0rapping procedure is ased on the elasticity of metals and is aimed atproducing a corrosion0resistant <oint; ith lo electrical resistance.

& ire is stretched around a terminal post y means of a it and slee)e; undersuch tension that the ire is deformed around the edges of the post. &fterrela-ation; a constant tension ill remain in the ire; and this ill e-ert sufficientpressure to maintain good electrical contact eteen the ire and the post.

13.3.1 TYPES OF WIRE>WRAP

Con)entional ire0rapping >class "?; only the stripped part of the ire israpped around the post; and the procedure is primarily used for hea)ier0gaugeire; i.e. ith a cross0sectional area of 2 mm2 or ao)e >see :etail & in thediagram elo?.

8odified ire0rapping >class &?; the stripped end must e rapped ' turnsaround the post; folloed y aout one turn of the insulated part of the ire. Thispro)ides significantly impro)ed resistance to )iration >see :etail " in thediagram ao)e?.

The ire must e a single0strand conductor ith good electrical properties. Thepost should e relati)ely hard. It is usually made of ron=e and has at least tosharp corners. The ire is usually tin0plated or sil)er0plated.

The ires are run unched together into looms along special paths on a circuitoard; or directly eteen the ire0rap points; criss0crossing the oard. Thelatter is $non as point0to0point iring. The ad)antages of point0to0point iringinclude simplified ser)ice; less ris$ of interference and loer eight.

13.3.2 TOOLS

The rapping tool consists of a metal rod; $non as the it; ith a central guide

hole; hich fits into the terminal post; and ith a narro groo)e in the periphery;hich fits the ire. The it is caused to rotate; and the ire is then stretchedaround the terminal post >see diagram elo?.



The tensile force during rapping around the post is decisi)e to the 7uality of theconnection and is determined y the dimensions of the tool. In other ords; it isimportant to employ the correct tools; hich are suitale for the intendedcomination of ire area and type of post.

Tools for stripping and ire0rap must ha)e gained type appro)al and must esu<ected to periodic inspection.

13.3.3 WIRE>WRAPPING PROCEDURE

Stripping is an e-tremely important operation in ire0rapping. The correctlength of ire must e stripped; so that the correct numer of turns ill eotained; and the ire must e entirely free from scratches and other stress0raisers.

The correct length of stripped end for modified mini0rapping is 2 mm for posts

⋅ 2 - ⋅ 2 and 3 mm for posts ⋅ 4 - ⋅ 4.

4. +it the stripped end of the ire as far as it ill go into the ire groo)e of theit >see :etail & in the diagram elo?.

41. +it the ire into the recess in the slee)e and end the ire toards theslee)e; along its length >see :etail " in the diagram elo?.

42. 9old the ire ith the fingers and push the tool into the terminal post; to theposition at hich rapping is to start >see :etail C in the diagram elo?.

43. :uring rapping; hold the tool straight and e-ert slight pressure in thedirection of the post >see :etail : in the diagram elo?.

If a connection must e re0rapped; cut the ire and unrap it ith anunrapping tool. >The unrapped end of the conductor must e not e usedagain?.

/rapping may e repeated on a post from hich earlier ire had eenunrapped; pro)ided that the post is undamaged.



13.3.4 INCORRECT WIRE>WRAPPING

/ire0rapping ith one of the defects specified elo shall e re<ected. >Refer toao)e diagram?.

• Insufficient numer of turns >see :etail &?

• ne turn not closed >see :etail "?.

• Spiral rapping >in the case of open turns and in spiral rapping; the distanceeteen the turns must not e-ceed one0half of the ire diameter? >see :etailC?.

• )erlapping turns >see :etail :?

• )erlapping ire0raps >see :etail ,?.

• /rap too far up on the post >the rap must not e-ceed eyond the chamferedpart of the post? >see :etail +?.

• Pro<ecting end of the ire >the rapping operation has een interrupted tooearly? >see :etail G?.

• Physical damage >the ire must e free from scratches? >see :etail 9?.

• The relie)ing turn; i.e. the ottom turn of insulated ire must e rappedaround at least three corners >see :etail I?.

• The ire must e run so that the ottom turn ill not e unound >see :etailA?.

• The ire must not e stretched eteen rap points.

13.3.5 'ODIFICATION AND REPAIRS

If a connection must e made again; cut off the ire and lea)e the ire0rap inposition or remo)e it y means of an unrapping tool. 6e)er pull the ire off.The corners of the post ill then e deformed and it ill e impossile to use thepost again.

The unrapped end of the ire must e straightened and rapped again. Theentire ire must e replaced or; if the length is sufficient; the end should e cutoff; stripped and rapped again.

If one conductor must e soldered >e.g. in a multi0strand conductor? to a post oris one unsatisfactory ire0rap must e soldered; all ire0raps on that

particular post shall e soldered.



13.3." 'ETHODS OF INSPECTION

The folloing methods of inspection are intended for chec$ing the tools andterminal posts; and shall e carried out as random sample tests in production.

Separate test post and conductors of the same type as those employed in the

rele)ant or$ shall e used.NoteJ The methods of inspection are of the destructi)e type.

The pull test in)ol)es applying a force to the ire0rap and measuring the forceat hich the ire0rap slides off the terminal post >see :etail & in the diagramao)e?.

W*/e S*Je > AWG D*+6ete/ '*n. P,,>o@@ Fo/e

;N<

2 .' 4

22 .! 3

24 . 3

2! .4 228

.32 2

3 .2 1

The unrapping test in)ol)es rapping the ire off the post >see :etail " in thediagram ao)e?. The test can e carried out in different aysJ

• "y means of special tools.

• "y means of the unrapping tool.

• "y hand.

:uring the unrapping test; the conductor must not e su<ected to tensionand@or torsion. The unrapping test is considered to e satisfactory ifunrapping is carried out ithout the ire fracturing.



14. INTERCONNECTING CA#LES

There are three types of ire connectionK permanent; semi0permanent and thosehich can e rapidly ro$en and remade for installation or maintenance purposesand hich usually in)ol)es a numer of circuits or ires hich must automaticallye connected correctly. The first to types are used in the manufacture andtesting of aircraft and generally employ terminal loc$s or strips. The last type; yno means the least important; employs plugs and soc$ets otherise referred to

as multi ay connectors.

14.1TER'INAL STRIPS

The earliest form of terminal loc$s consisted of phenolic mouldings hichhoused to or more terminals and ere a)ailale in )arious si=es. Connectionas made y gripping the ire under a screed don terminal head. &connection such as this is totally unpredictale; if too much pressure is applied itill crush the conductor; mechanically ea$ening it; remo)ing the tinning andsometimes e)en fracturing one or more of the strands. 8ethods li$e this aretotally unacceptale for aircraft use.

14.1.1 S#AC TER'INAL #LOCKS

Immediately after /orld /ar II the ,lectrical Committee of the Society of "ritish &ircraft Constructors de)eloped a ne terminal loc$ $non as the S.".&.C.system. This terminal loc$ ore some resemlance to a system used onGerman military aircraft during the ar; ut as more fully de)eloped. Itcomprised a loc$ of phenolic insulation arranged ith a numer of arriers toaccommodate from to 1 cale ays. The actual connectors ere in eithersingle or doule tier and incorporated oth a spring loc$ a loc$ing scre. Theconnection as made on circular ferrules crimped onto the ends of the cales.The simple insertion of the crimped end into the terminal loc$ metalor$ensured a satisfactory spring loaded electrical connection hich could e

rendered permanent y tightening don the scre.

The loc$ as ultimately found to e too large for the confined conditionsresulting from the use of e-tended electrical systems and panels in laterinstallations. & miniature loc$ of a similar nature as de)eloped ut ne)erproduced.



14.1.2 PLESSEY TER'INAL #LOCKS

/hilst the "ritish ere preoccupied ith elaorate designs; in &mericaterminations ere; as they still are; on plastic strip ases ith fi-ed terminalpillars; the cales eing fitted ith ring type tags hich ere placed o)er thepillars and clamped don ith an ordinary nut. This method has een e-tremelysuccessful in pro)iding solid reliale connections in thousands of aircraft o)ermillions of hours.

The decision not to proceed ith the S.".&.C. miniature loc$ led the PlesseyCompany to de)elop a smaller terminal loc$ hich as used e-tensi)ely on"ritish aircraft. The unit could accommodate up to 2 terminations and employeda spade type crimped terminal; loc$ing into a metal clamp ith spring retainer;hich could e further secured y a scre to from a rigid connection; as shonao)e.

14.1.3 WARD #ROOK TER'INAL #LOCKS

5ater uilt "ritish aircraft use a terminal loc$ hich has scre studs formounting ring terminals. These loc$s are called ard "roo$ terminal loc$s. Thering tags are secured using special tor7ue spanners.

These terminal loc$s are made from Polyethersulphate 43P and are eitherlac$ or red in colour. The scre studs are made of stainless steel and securedy steel cadmium plated stiff nuts called FEayloc$ fastenersF. They are supplied inoth single and doule ro of either 1;2;3; or 1 ay configuration.



14.1.4 TER'INAL UNCTION 'ODULE

Today neer types of terminal loc$ are a)ailale; ha)ing loer to-icity togetherith easier construction and manoeu)raility of pins. & typical e-ample of this isthe Terminal Aunction 8odule shon elo.

These terminal loc$s ha)e a temperature range from 0°C to 1%°C. They aremade from :iallyl Phthalate and are red or lac$ in colour. They are sealed ithflourosilicone ruer coloured red or hite. The contacts and the us plateassemlies are made from gold plated copper alloy. &lthough the us platescannot e seen; the layout is indicated y trace lines on the top of each moduleas shon elo.

The contact si=es are determined y their current rating and each contact si=ecan accommodate more than one conductor si=e as shon eloJ

• Si=e 21 0 3 amps conductor si=es 22 and 24

• Si=e 2 0 %. ampsconductor si=es 2;22 and 24• Si=e 1! 0 13 amps conductor si=es 1!;1' and 2

• Si=e 12 0 23 amps conductor si=es 12 and 14

The dielectric use can ithstand 1 )olts rms at sea le)el.



14.2CONNECTORS

,lectrical connects are designed in many shapes and si=es to facilitate theinstallation and maintenance of electrical circuits and e7uipment in all types ofaircraft. +or e-ample; if may e necessary to replace a damaged section ofelectrical harness in an aircraft. If the section of harness is connect othersections y connectors; it is a comparati)ely simple matter to unplug the sectionat oth ends and remo)e the damaged section. & completely ne section maythen e 7uic$ly installed. If the damaged section ere connected y terminal

strips; the operation ould ta$e a considerale amount of time. It can e seenthat if larger electrical or electronic e7uipment ere connect y terminal strips asimilar prolem ould result.

& conductor assemly comprises to principal parts. These parts are generallycalled the 7,0 and soet or /ee7t+,e. The plug section generally containsFpin soc$etsF and the soc$et or receptacle; contains pins. Some confusion mayarise concerning plugs and receptacles ecause some authorities call the sectioncontaining the pin soc$ets; Zthe receptacleD and the section containing the pinsZthe plugD. In many cases it is simpler to refer to the to sections as Zthe soc$etsectionD and Zthe pin sectionD. /hiche)er ay the connectors are descried; theli)e side of the circuit should alays e connected to the soc$et section. This

arrangement reduced the ris$s of shorting the circuit and of electrical shoc$.Connectors may e fi-ed or free items; i.e. fi-ed in a <unction o-; panel ore7uipment; or free as part of a loom assemly to couple onto a fi-ed item.

There are numerous )ariations in the design of connectors go)erned principallyy the re7uirements of the circuit; the numer of conductors to e terminated andthe en)ironmental conditions in hich the connector is to e used. The odies orshells are mostly of light alloy or stainless steel finished o)erall ith cadmiumplating. They may e pro)ided ith either a male or female thread; or may e ofthe ayonet type for 7uic$ connection and disconnection. Connectors used onrac$ mounted e7uipment may e s7uare and simply push together; retentioneing achie)ed y loc$ing the e7uipment into the rac$.

Polarising $eys and $eyays are pro)ided to ensure that plugs and soc$ets matecorrectly; they also pre)ent mo)ement eteen the contacts; therey reducingstrain hen the coupling rings are tightened.

The shells of free connectors are e-tended as necessary y the attachment ofoutlets. These pro)ide a means of supporting the cales at the point of entry tothe connector; therey pre)enting straining of the conductor and pin or soc$et <oints; they also pre)ent displacement of the contacts in the softer materialinsulators. In many cases special clamps are pro)ided; these compress the softinsulation material so that it grips the conductors; thus pro)iding support andpre)enting the ingress of dirt or moisture.

To pre)ent distortion of the insulated moulding and to assist in correct mating ofthe connectors; all positions in the connector should e fitted ith a pin or soc$etas appropriate; in some instances this may re7uire the use of special pininsertion tools. In addition; a special ZfillerD insert must e fitted to ensure correctcale support and to pre)ent the ingress of dirt or moisture.

Plug contacts are usually solid round pins; and soc$ets contacts ha)e a resilientsection hich is designed to grip the mating pin. The contacts are retained inposition y insulators or inserts as they are often called; hich are a sliding fit inthe shells and secured y retaining rings and @or nuts. Insulators are made froma )ariety of materials depending on the connection application.

Cales ere originally attached to connector pins and soc$ets y soldering and

although retained ithin some e7uipment; this has no een superceded ycrimping techni7ues hich ha)e already een studied.



Identification of pins and soc$ets is achie)ed y numering or lettering. In manyconnectors; ut not all; a spiralling guideline emossed on the faces of the insertsis used to signify the se7uence. /hen letters are used I; and Q are not usedand to allo for larger numers of contacts capitals are used first; then lo caseletters and then doule capital; i.e. &&.

To pro)ide information in respect of all manufacturers and all specifications iseyond the scope of these notes; students must therefore consult othmanufacturers literature and maintenance manuals hene)er possile.

The diagrams and procedures that follo are only intended to gi)e an insight intohat can e considered as a su<ect in its on right. :etailed information muste otained from the rele)ant aircraft maintenance manuals.

A +/*et- o@ o, onneto/s

O, #en* 'S t-7e onneto/s



Asse6,- o@ '*,>C>2"4$2 T-7e Conneto/s

Connector Part 6umering

G. Typical ITT Cannon Part 6umer

KPSE )) E > 1$ > 32 S 9 ; <

8odification

&lternate Insert Position

P O Pins S O Soc$ets

Insert &rrangement

Shell Si=e

Class

/all 8ounted Receptacle

1 Cale Connecting Plug

2 "o- 8ounted Receptacle

! Straight Plug

% Aam 6ut Receptacle

' *N &ngle Plug

9. Typical "urndy Part 6umer

L 22 T F 55 P ) N A

Eeyay Position

Shell Style

Contact StyleFPF for Pin; FSF for Soc$et

Insert &rrangement

Class F,F Grommet SealF+F Grommet Seal ith StrainRelief

Shell Style

Shell Si=e

Smooth "antam

Inse/t Con@*0/+t*ons @o/ 'IL>C>2"4$2 Se/*es Conneto/s

(ie shon is +ront +ace of Pin Insert.

A*t*on+, Inse/t Con@*0/+t*ons @o/ 'IL>C>2"4$2 Se/*es Conneto/s



(ie shon is +ront +ace of Pin Insert.

Re6o+, too,s @o/ n=*/e onneto/s > ;/e+/ /e,e+se onneto/s<

Inst+,,*n0 +n /e6o+, too,s @o/ @/ont /e,e+se onneto/sO7e/+t*n0 Inst/t*ons > *nst+,,*n0 too,s

44. Select correct insertion tool and place contact@ire assemly in tool.

I. `2 contacts ith insulation cups are inserted y sliding cup into frontend of insertion tip until end of cup utts against shoulder in insertiontip. >see diagram 1 elo?.

A. Contacts ithout insulation cups are inserted y sliding ire arrel intofront end of insertion tip until contact shoulder utts against insertiontip. >see diagram1 elo?.

33. &lign tool and contact a-ially ith grommet hole and carefully guide contactthrough grommet into loc$ position. >see diagram 2 elo?.

O7e/+t*n0 Inst/t*ons > /e6o+, too,s



4. Select correct contact remo)al tool.

4!. Tool must e held in straight lineK parallel to contact and s7uare to connectorface.

4%. Insert remo)al tool tip into connector. Push plunger slide forard to e<ectcontact.

NoteJ Plunger slide must remain in retracted position as remo)al tool tip isinserted into connect.

T=eeJe/ t-7e *nst+,,*n0 +n /e6o+, too,s @o/ /e+/ /e,e+se onneto/s.

Ient*@*+t*on

Inst+,,*n0 Too,8

Co,o/ Cont+t S*Je P+/t No.

Bello 12 8S2%4*&12

"lue 1! 8S2%4*&1!

Red 2 8S2%4*&2

"ron 22 8S2%4*&22

"lac$ 22:; 228 8S2%4*&228

Re6o+, Too,8

Co,o/ Cont+t S*Je P+/t No.

Bello 12 8S2%4*R12

"lue 1! 8S2%4*R1!

Red 2 8S2%4*R2

"ron 22 8S2%4*R22

"lac$ 22:; 228 8S2%4*R228



Inst/t*ons

To *nst+,, ont+ts8

4'. pen the tool tips y s7uee=ing the handles and the tips around the ireinsulation. Slide tool along the ire until tip ends utt against the shoulder onthe contact.

4*. Carefully push the contact forard and directly in line ith the grommet holeuntil contact is felt to snap into position.

. Slide the tool ac$ along the ire insulation until it clears the grommet andremo)e tool from ire.

To /e6oe ont+ts8

1. pen the tool tips sufficiently to e places around the ire insulation. Slidethe tool don the ire until tool tips enter the grommet and come to apositi)e stop >see diagram elo?. & slight increase in resistance ill enoticed <ust efore contact.

2. 9olding the tool tips firmly against the positi)e stop on the contact; grip theire and simultaneously remo)e the tool; contact and ire.

C+t*on The tips on installing and remo)al tools used on small contacts ha)e)ery thin all sections. This causes them to ha)e sharp edges hichcan cut the ire insulation or connector sealing grommet.

:o not s7uee=e; spread; tip or rotate the tee=ers hile entering theconnector grommet.



Inst/t*ons Fo/ P,+st* Too,s.

Inst+,,*n0 ;o,o/e en<8

3. 9old the insertion half of tool>coloured? eteen the thum andforefinger and lay the ire to einserted along the slot; lea)ing aoutVM protruding from the end of the tool

to the crimp arrel of the contact.

4. S7uee=e the ire hard into the tool atthe tip; eteen the thum andforefinger; and at the same time 7uic$lypull the protruding ire ith the otherhand aay from the tool.

. The ire ill no ha)e snapped intoplace. Pull it ac$ through tool until thetip seats on the ac$ end of the crimparrel.

!. 9olding the connector ith the rear sealfacing you sloly push the contactstraight into the connector seal.

%. & firm stop ill e e)ident hen thecontact positi)ely seats in theconnector.



Re6o+, ;=:*te en<8

'. /ith the rear of connector facing you;lay the ire of contact to e remo)edalong the slot of remo)al half >hite? ofthe tool; lea)ing aout VM from the end

of the tool to the rear of the connector.

*. S7uee=e the ire hard into the tooleteen the thum and forefinger aoutM from the tip and at the same time7uic$ly pull the connector aay from thetool ith the other hand.

!. The ire ill no ha)e snapped intoplace. Slide the tool don o)er the ireand into the rear seal and push it slolyinto the connector until a positi)eresistance is felt. &t this time thecontact retaining clip is in the unloc$position.

!1. Press the ire of the contact to eremo)ed against the serrations of theplastic tool and pull oth the tool andthe contact0ire assemly out of theconnector.

C+t*on8 :o not tip; spread or rotate toolhile it is in the connector.



"lan$ Page



15. 'EASURING INSTRU'ENTS

The )ariety of electrical and electronic circuits is fore)er on the increase. The)oltage; current and fre7uency ranges o)er hich the circuits operate is immenseand has undergone many changes o)er the years. To enale efficientmaintenance and testing of these circuits; a range of instruments are re7uiredthat enale these )ariales to e effecti)ely and accurately measured. Theintroduction of digital measuring instruments has simplified the tas$ of ma$ing

measurements and greatly impro)ed accuracy; hoe)er; there remains certainsituations that re7uire the use of an analogue instrument.

15.1#ASIC 'O(ING COIL TYPE

15.1.1 CONSTRUCTION

& asic mo)ing coil instrument comprises a horse0shoe shaped permanentmagnet that is aged to reduce the rate at hich the flu- density decreases. Thepoles of the magnet are shaped and ha)e a soft iron cylinder; supported y rasssupports; positioned eteen them. This arrangement reduces the reluctance ofthe magnetic circuit and produces a radial field in the airgap eteen the cylinderand the pole pieces. It is in this airgap that the coil rotates.

The coil consists of fine copper ire ound on an aluminium former that is fittedith a spindle at either end. The coil is terminated on the spindles; hich areinsulated from the aluminium former. The spindles run in <eelled earings thatare mounted in non magnetic frames positioned either side of the magnet. Thecoil is free to rotate in the airgap eteen the cylinder and the permanent

magnet; although its angle of rotation is limited due to the cylinder supports. Thepointer is attached to one of the spindles and rotates ith the coil and aluminiumformer; mo)ing across the scale or scales on the face of the instrument.

/ith no opposition to the motor tor7ue; the pointer ould simply mo)e across thescale to the end stop. pposition is pro)ided y to contra0ound springs thatare attached at one end to the spindle and at the other to the spindle supportframes. The springs are contra0ound to pro)ide temperature compensation andalso pro)ide for electrical connection to the mo)ing coil.



15.1.2 PRINCIPLE OF OPERATION

/ith no current floing in the coil; there is a uniform field in the air gap eteenthe permanent magnet and the soft iron cylinder as shon in the diagram.

/hen the meter is connected to an electrical circuit; current flos through the coilcreating a field around its conductors. The direction of field rotation can e foundusing the Right 9and Grasp rule. The field around the conductors of the coil

react ith the main field; the field ao)e the conductor on the right isstrengthened hilst the field elo the conductor is ea$ened; causing theconductor to mo)e don. The field ao)e the conductor on the left is ea$ened;hilst the field elo is strengthened; causing the conductor to mo)e up. "othconductors form part of the coil; so the coil ill rotate on its pi)ots. &s the coilrotates it ill continue to distort the main field; ithout a controlling force tooppose the mo)ement; e)en a small current ould cause the coil to rotate to itsend stop and indicate full scale deflection. Control for the mo)ement is pro)idedy the contra ound springs. &s the coil rotates; one spring is compressed theother e-tended.

9oo$es la states that the e-tension of an elastic ody is directly proportional to

the applied force; pro)ided the force remains ithin the elastic limits of thematerial. This means that the relationship eteen the e-tension and the appliedforce is linear; the applied force is the motor tor7ue; hich also has a linearrelationship ith the current creating it. Therefore the meter mo)ement is linearand the scale can e linear.

The coil and pointer ill come to rest hen the tor7ue created y the springscancels the tor7ue created y the mo)ing coil. The larger the current floing inthe coil; the greater the tor7ue produced and the further the coil ill rotate.Rotation of the coil mo)es the pointer across a scale calirated to indicate the)alue of circuit current or )oltage.

The current re7uired to mo)e the pointer to the furthest point on the scale is

called @,, s+,e e@,et*on //ent; i.e. the current re7uired to mo)ed thepointer to full scale deflection. If the current in the coil is less than I f.s.d. thepointer ill ta$e up a position eteen =ero and full scale deflection.



15.1.3 DA'PING

The mo)ing coil meter is designed to mo)e 7uic$ly from =ero to the re7uired)alue. /ith no damping; momentum ill cause the mo)ement to o)ershoot./hen the mo)ement o)ershoots; the force created y the springs is greater thanthe tor7ue created y the coil; so the meter sings in the opposite direction ac$toards its intended position. &gain; ith no damping; the meter ill o)ershoot.The tor7ue produced y the fields is no greater than the force produced y the

springs and so the meter sings ac$ in the original direction toards itsintended position. /ith no damping the mo)ement oscillates; each o)er0singeing smaller than the pre)ious; until the mo)ement comes to rest. To pre)entthe meter oscillating; a damping system is incorporated.

:amping is pro)ided y the aluminium former on hich the coil is ound. &luminium is a conductor. /hen mo)ed in the field of the permanent magnetthe former has emfDs induced in it that result in eddy currents and the productionof a field. The field around the former opposes the main field and tries to pre)entmo)ement; thus pro)iding damping. The faster the meter mo)es; the greater theinduced emf; eddy currents and field; and the greater the damping pro)ided.

The amount of damping used is important; too little and the mo)ement illoscillate; too much and the mo)ement ill e sluggish and may not stop at thecorrect position; the motor tor7ue eing unale to o)ercome the damping force.

/hen the damping is insufficient; the mo)ement is said to e under0damped;hen too much damping is pro)ided the meter is o)er0damped.

The amount of damping necessary to get the meter to mo)e to the correctposition ith no o)er0sings; in the shortest possile time is called /*t*+,+67*n0. Critical damping is one specific )alue of damping; this is difficult tootain and is easily changed y changes in operating conditions; any changesaffect the response of the mo)ement.

8eters are normally set up ith *e+, +67*n0. Ideal damping allos the meterto mo)e to its intended position ith one o)er0sing. The initial speed ofresponse is 7uic$er than a critically damped mo)ement; hoe)er; the meterta$es slightly longer to come to rest at the re7uired position. &n ad)antage of

ideal damping is that; as the meter ages and friction increases; the dampingtends toards critical damping; thus impro)ing its response time.

15.1.4 PARALLA9 ERROR

/hen the )alue displayed on an instrument is read; the )alue returned isdependent on the position of the reader. If the reader mo)es; the )alue appearsto change; this is $non as 7+/+,,+ e//o/ . To pre)ent paralla- error; somemeters ha)e a mirror fitted ehind the pointer; ad<acent to the scale. /henreading the meter; the oser)er positions themsel)es so that the reflection of thepointer is hidden y the pointer itself. #nder these conditions the meter is eingread correctly.



15.1.5 'ETER POSITION

,rrors in meter readings can also e caused y incorrectly positioning the meter.If a meter is stood upright during caliration; it should e stood upright hilstma$ing measurements; if the meter as laid don for caliration it should e laiddon hilst ma$ing measurements.

15.1." E9TENDING THE 'ETER RANGE

Typical )alues of full scale current and )oltage for a asic mo)ing coil are 1µ &and . )olts. This ma$es it far too sensiti)e for use in practical circuits here)oltages and currents far in e-cess of these )alues are encountered. The rangeof use can e e-tended y using shunts for higher currents; and multipliers forhigher )oltages.

15.1.".1 Dete/6*n*n0 t:e s:nt /es*st+ne

/hen using the meter to measure current itmust e connected in series ith the circuitunder test. The ma-imum current hichcan pass through the mo)ement is that)alue gi)ing full scale deflection; theremainder must e made to ypass it. Thisis achie)ed y connecting a resistor inparallel ith the mo)ement; the resistoreing $non as a shunt

To determine the )alue of shunt resistor re7uired ;(fsd must e calculated. (fsd cane calculated from the meter resistance and Ifsd; oth of hich are normally

ritten on the mo)ement; (fsd O Ifsd × Rmeter . In a parallel circuit the )oltage iscommon to oth arms.

The amount of current that the shunt must ypass is the difference eteen thetotal current and the mo)ement currentK Is O IT 0 Imeter

The )alue of shunt resistance can no e calculated from (fsd and IS.

RS

/hen using a shunt it should e connected directly to the main conductors of thecircuit under test; the meter mo)ement should then e connected to the shunt.This ill pre)ent an accidental open circuit damaging the meter mo)ement.

15.1.".2 Dete/6*n*n0 t:e 6,t*7,*e/ /es*st+ne

/hen using the meter to measure )oltages it is connected in parallel ith thecircuit under test. The ma-imum current that can pass through the mo)ement isagain that hich gi)es full scale deflection; this is determined y the circuit)oltage and the meter resistance; and may ell e-ceed Ifsd.

To limit the current through the mo)ement; a resistor must e connected in seriesith it. This resistor is $non as a multiplier.

To determine the multiplier )alue; Ifsd and the meter resistance must e otainedfrom the mo)ement. The series comination of meter resistance and multiplier

resistance must limit the ma-imum current to Ifsd. ThereforeJ



Ifsd O as RTotoal O Rmeter X Rmult

Ifsd O

Rmeter X Rmult O

therefore R6,t > R6ete/

Shunts and multipliers should oth e made from metals that ha)e lotemperature co0efficient of resistance; metals such as 8anganin and ,ure$a.

15.1.! 'ETER LOADING

/hene)er a meter is connected into an electrical circuit it changes the totalcircuit resistance; and therefore changes the )alues of )oltage and current in thecircuit. This means that the )alues of )oltage and current indicated on the meterill differ from those in the circuit hen the meter is disconnected. The degree oferror caused depends on the resistance )alue of the meter used.

&n ammeter and its shunt are connected in series ith the circuit under test;therefore in order not to change the circuit current their resistance must e assmall as possile. If the meter resistance is too large; the circuit current ill ereduced and the meter ill under read.

& )oltmeter and its multiplier are connected in parallel ith the circuit under test;therefore the comined resistance must e as high as possile in order not toshort circuit the circuit under test. If the resistance is too lo; the ma<ority ofcurrent ill flo through the meter instead of the circuit under test; changing the)oltage drop across the circuit component.

#sing a meter ith an incorrect resistance )alue can cause )ery large errors inthe measurements ta$en.

15.1.$ OH'QS PER (OLT

/hen a meter is used as a )oltmeter; the degree of circuit loading is indicated y

the Hhms per )olt )alue. This is calculated from the comination of meter andmultiplier resistance and the full scale deflection )oltage of the meter.

8eter X 8ultiplier resistance O 1$Ω

fsd )oltage O 1 )olts

hms@)olt O 1 @1 O 1

8eter X 8ultiplier resistance O 28Ω

fsd )oltage O 1 )olts

hms @)olt O 2 @ 1 O 2

The second meter in the e-amples ao)e has the higher hms per )olt )alueand ill therefore cause a smaller loading effect on the circuit hen used for)oltage measurement.

&n alternati)e method used for calculating the hm per )olt )alue s to ta$e thereciprocal of the fsd current.

If Ifsd O 1m& the hms per )olt )alue ould e 1@⋅ 1 O 1

If Ifsd O µ & the hms per )olt )alue ould e 1@⋅ O 2

The hms per )olt )alue also gi)es an indication as to the sensiti)ity of themeter; and is sometimes called the H+igure of 8erit.



There are numerous types digital meters on the mar$et; ut e)en the most asic

ha)e input impedances of 28Ω or greater for d.c. measurement and 18Ω fora.c. The fre7uency range )aries from to 2 $9= upards. The )alues for eachmeter should e confirmed efore use.

15.1.& 'EASURING RESISTANCE

In order to use a asic mo)ing coil instrument for measurement of resistance; aattery must e connected in series ith the mo)ement. and the circuit under

test. To limit the circuit current to Ifsd; a current limiting resistor is connected inseries ith the mo)ement and circuit under test.

+or the meter to indicate correctly; the current must flo from the red to the lac$terminal of the meter. The positi)e terminal of the cell must therefore econnected to the meter mo)ement and the negati)e terminal to the red terminalof the meter. #nder these conditions; the lac$ terminal of the meter is positi)eith respect to the red terminal; and current flos through the circuit under testfrom lac$ to red.

/hen the proes or meter terminals are open circuit =ero current flos and themeter should indicate ma-imum resistance; that is no pointer mo)ement. /henthe test leads are shorted together ma-imum current flos and the meter should

mo)e to fsd; indicating =ero resistance. /hen a resistor is connected eteenthe terminals; the current ill e determined y the )alue of the resistance andthe meter ill mo)e to some intermediate position to indicate the )alue of theresistor.

/hen using a multimeter to measure resistance; the meter mo)ement isdetermined y the amount of current floing in the circuit under test. Inaccordance ith hms la; the )alue of current is determined y oth the circuitresistance and the circuit )oltage; therefore any change in )oltage ill affect the)alue of current. /hen a multimeter is used for resistance measurement; thecircuit )oltage is deri)ed from the cell; therefore if the cell )oltage decreases; thecircuit current ill decrease and the meter ill under0read. Cell )oltage reducesith age; therefore another )ariale resistor must e connected in series ith themeter mo)ement and the circuit under test to enale correction. &s the cell ages;the )alue of resistance is reduced increasing the circuit current to its correct)alue.



15.2 RATIO'ETER TYPE INSTRU'ENTS

& ratiometer is asically a mo)ing coil instrument that uses to coils as opposedto a single coil. ne coil is used to measure current; the other )oltage. "othcoils are mounted on the same spindle ut are ound in such a manner that thetor7ueFs produced are in opposition; i.e. one coil tries to mo)e the pointercloc$ise the other anti0cloc$ise. The air gap eteen the soft iron spindle onhich the coils are ound and the permanent magnet eteen hich it rotates is

no0linear. This creates a reduction in tor7ue as the coil mo)es into the larger airgap and )ice )ersa.

#nder most conditions current flos in oth coils of a ratiometer. The coil iththe larger current creates a tor7ue that causes that coil to rotate toards thelarger airgap; decreasing the tor7ue it is producing. &t the same time the othercoil is pushed into the smaller airgap; creating an increasing tor7ue. /hen theto tor7ueFs are alanced the pointer stops mo)ing.

The to coils can e inter0connected in to different ays as shon elo.

In circuit 1; the current coil measures the sum of the current floing in theun$non resistor and the )oltage coil; and the )oltage coil measures the )oltageacross the un$non resistance only.

In circuit 2; the )oltage coil measures the )oltage drop across oth the currentcoil and the un$non resistance; and the current coil only measures currentthrough the un$non resistor.

If the un$non resistance is high; i.e. hen carrying out an insulation resistancechec$; it is etter to use circuit numer 2. /hen measuring a large resistance thecurrent flo through it ill e lo. If circuit 1 ere used; the current through the)oltage coil ould e large in comparison; creating a large error in the currentmeasured. #sing circuit 2; the lo resistance of the series current coil has littleeffect on circuit current; and the )oltage drop across the small resistance of thecurrent coil is negligile in comparison to that of the un$non resistance.

If the un$non resistance is lo; i.e. hen carrying out a onding chec$; it isetter to use circuit numer 1. /hen measuring a lo resistance the currentthrough it ill e relati)ely high. If circuit 2 ere used; the )oltage drop across thecurrent coil ould e )ery large in comparison to that across the un$non

resistor; creating a large error in the )oltage measured. #sing circuit 1; the highresistance of the )oltage coil dras little current in comparison to the un$nonresistor; creating a negligile error in the current reading; and the )oltage coilonly measures the )oltage drop across the un$non resistor.

15.2.1 THE #ONDING TESTER

The "onding tester employs the ratiometer principle; ecause the e-pectedresistance )alues are small; the to coils are connected as in circuit 1. &s onlysmall resistances are to e measured; currents up to one amp may e re7uired;therefore a small et 6I+, cell is used as the poer supply.



To test leads are used; a ! ft MstaticM lead that is fitted ith a single spi$e andan open ended ring terminal; and a si- foot lead that is fitted ith a doule spi$e.The doule spi$e acts as a sitch; oth spi$es ha)ing to e in contact ith theond under test in order for the meter to or$.

The ! ftlead isconnected toa fi-edterminalpoint; eitherthe aircraftmain onddatum or asecondaryondingpoint thusensuring agoodconnection. The ! ft test lead is pressed onto the item hose resistance is to emeasured.

/hen the to spi$es of the ! ft test lead are shorted y a suitale conductor andthe ! ft lead is left disconnected; the current through the )oltage and currentcoils is the same; hoe)er; the tor7ue produced y the )oltage coil is arranged toe greater than the tor7ue produced y the current coil and conse7uently a fullscale reading is otained; indicating a high resistance.

/hen the single spi$e of the ! ft leadis used to short circuit the doulespi$e of the ! ft lead; the )oltage coilis shunted y the test circuit. #nderthese conditions no current flos inthe )oltage coil; and conse7uently thepointer mo)es; under the influence ofthe current coil; to gi)e a =eroresistance indication.

/hen the meter is used tomeasure the resistance of aond; the )oltage coil is nolonger shorted. Some currentill flo through the )oltage coil

and some ill flo through thecircuit under test. The ratio ofcurrent through the to paths isdetermined y the )alue of theresistance eing tested and themeter ill ta$e up anintermediate position to indicatethe )alue of this resistance.



Prior to carrying out a onding test; a chec$ should e made on the state of thenic$el0al$aline cell of the tester y oser)ing thatJ

• a full0scale deflection of the meter is otained hen the to spi$es of the !0foot cale proe are shorted y a suitale conductorK and

• that the meter reads =ero hen the to spi$es of the !0foot proe are shortedy the single spi$e of the !0foot proe.

The !0foot lead of the test e7uipment should e connected to the main earth

>also $non as the ond datum point? at the terminal points hich are usuallyshon diagrammatically in the rele)ant &ircraft 8aintenance 8anual. Since thelength of a standard onding tester lead is ! feet; the measurement eteen thee-tremities of the larger types of aircraft may ha)e to e done y selecting one ormore main earth points successi)ely; in hich e)ent the resistance )alueeteen the main earth points should e chec$ed efore proceeding to chec$ theremote point.

The !0foot test lead should e used to chec$ the resistance eteen selectedpointsK these are usually specified in the onding test schedule or the8aintenance 8anual for the aircraft concerned. /hen the to spi$es of the testlead proe ate rought into contact ith the aircraft part; the test0meter illindicate; in ohms; the resistance of the ond.

It may e necessary to remo)e a small area of protecti)e finish >e.g. strippalelac7uer or paint? in order to carry out a "onding chec$; any protecti)e treatmentremo)ed must e re0applied after the measurements ha)e een ta$en.

15.2.2 THE INSULATION RESISTANCE TESTER

The Insulation resistance tester also uses the ratiometer principle; ecause thee-pected )alues of resistance are high; circuit 2 from chapter 34.2 is used. Thehigh )alues of resistance eing measured also mean that; unli$e the ondingtester; any test leads can e used; although they are generally supplied ith theinstrument. In order to generate a useale current; a high supply )oltage is

re7uired; this cannot e otained from a attery and therefore a hand oundgenerator is used; this negates the need for an on@off sitch.

If the test terminals are open circuited;the current through the current deflection coil is =ero. The generator currentflos entirely through the )oltage or control coil and the pointer is arranged toindicate infinity on the scale. If the test terminals are short circuited; current flosthrough oth coils and the pointer is arranged to indicate =ero on the scale. &finite )alue of resistance eteen the test terminals ill cause the pointer to ta$eup an intermediate position dependent on the )alue of the resistance.



15.2.3 CARRYING OUT AN INSULATION RESISTANCE TEST

Insulation resistance testing is carried out ith an instrument hose or$ing)oltage is nominally 2(; ut hich does not e-ceed 3 )olts. Insulationtesters are also a)ailale in a range of higher )oltages; these should only eused if specified in the maintenance manual. Care must e ta$en to ensure thecorrect )oltage tester is used.

Tests are normally carried out eteen indi)idual conductors and also eteenindi)idual conductors and earth.

/hen the insulation test is completed; functional chec$s should e carried out toascertain the ser)iceaility of the system. If a fault is detected it should eratified and the insulation test repeated.

Prior to carrying out the insulation resistance chec$; the folloing should eoser)edJ

• The attery and e-ternal supply must e disconnected.

• &ll rele)ant C"Fs must e closed.

• &ll appropriate sitches should e set for normal in0flight operation. &ll othersitches in)ol)ed should e put to F6F or minimum resistance position.

• &ll rele)ant e7uipment must e disconnected. This includes radio; electronicand supply systems.

• /here necessary; components such as out0puts and relays may e ridgedto ensure continuity of the circuit.

• &ll necessary safety precautions must e ta$en.

• ,nsure no semi0conductor de)ices are included ithin the circuits to etested.

&ll insulation resistance tests carried out should ensure the proper functioning ofoth indi)idual and integrated elements of the circuits. They should e carried

out in accordance ith the details of the maintenance manual; iring diagrammanual or modification instruction. n completion; all connections should eremade and all sitches reset to their correct positions.

The results otained may signify little hen ta$en on their on. They should erelated to the results otained during pre)ious tests. This ill indicate a possiledeterioration in the insulation resistance.

Typical minimum )alues areJ

• /iring 0 not less than 18Ω

• Terminals 0 not less than 18Ω

• "eteen terminals unched together and also to earth

8Ω



1". AIRCRAFT 'ANUALS

The purpose of this section is to gi)e an introduction to the pulicationsassociated ith the maintenance of aircraft. &lthough much of the terminology isthe same; there is a mar$ed difference eteen the manuals associated ithpulic transport aircraft and the manuals associated ith other categories ofaircraft; therefore the to ill e loo$ed at indi)idually.

1".1 LARGE CO''ERCIAL AIRCRAFT

8aintenance documentation associated ith large commercial aircraft isproduced in a )ariety of different formats; in the main this is due to changingtechnology. Bou may encounter any of these formats and are therefore e-pectedto e familiar ith all of them.

• P+7e/ . Printed oth sides; generally &4 or letter si=e depending on origin;although some manuals use other formats.

• '*/o@*,6. Photographed )ersion of the manuals put onto hat loo$s li$ecine0film; contained ithin a cartridge rather li$e a small )ideo cassette.This format re7uires the use of special reader0printers. The printer is used

to ma$e a or$ing Fhard copyF of any section rele)ant to a maintenancetas$. nce the tas$ is completed the hard copy must e destroyed.

• CDRo6. C:Rom formats )ary. In some cases the manual is presented)ery much li$e the paper )ersion and suffers the same limitations. In othercases the manuals ha)e een formatted especially for use on the computergi)ing far greater fle-iility. &lthough this format re7uires the use of acomputer; the use of a laptop ma$es the documentation transportaleunli$e the oo$ )ersion.

• D(D. This is the format eing used for the latest "oeing manuals.

8anuals are still produced in all of the ao)e formats ecause some operators

are not up0to0date ith the latest technology; others prefer certain formats andsome are loath to change. There are ad)antages and disad)antages to eachformat; although the riter elie)es that C:Rom )ersions designed specificallyfor computer use are far superior and ill no dout ta$e o)er in time.

1".1.1 ATA 1))

The ma<ority of manufacturers and operators of commercial aircraft use the &T&1 Specification as the plan for the manuals needed to maintain; o)erhaul; andrepair their aircraft. It is one of se)eral such specifications issued y )ariousodies; ut has gained much ider acceptance than any of its competitors andill therefore form the asis of these notes.

The specification as dran up y the memer airlines of the &ir Transport &ssociation y &merica; and as thus prepared primarily to meet the needs oflarge passenger carrying airlines. Its asic principles ha)e; hoe)er; eensuccessfully applied to small aircraft.

ne of the main aims of the specification is to ensure that all the informationneeded y an operator is included in one or other of the manuals pro)ided y theaircraft manufacturer; e-cept accessory o)erhaul data hich is co)ered in )endoro)erhaul manuals. This is in contrast ith some other specifications; hichre7uire not only the use of manuals supplied y the aircraft manufacturer; ut thee-tensi)e use of )endor manuals for descripti)e; ser)icing and maintenance dataon accessory e7uipment.



&T& Specification 1 calls for the folloing manualsJ

• 8aintenance 8anual

• /iring :iagram 8anual

• Illustrated Parts Catalogue

• )erhaul 8anual

• Structure Repair 8anual

• Tool and ,7uipment 5ists

• /eight and "alance 8anual

The Specification calls for another medium for Information0Ser)ice "ulletins.These ulletins pro)ide to different types of information. Some ulletins pro)idea 7uic$ path for any urgent Monce o)erM inspections that may ha)e eenhighlighted y a fault disco)ered on another aircraft of the same typeK otherspro)ide information on modifications; e-plaining their purpose and gi)ing themethod of incorporation.

&ccording to the Specification; the manufacturerDs recommended time limits for

inspections; tests and o)erhaul should e pro)ided in a separate manualhere)er possile. These time limits are contained in a separate manual calledthe 8aintenance Schedule. The maintenance schedule can e amended y theoperator; ut only if the amendment increases the scope; or reduces the timeinter)al.

The Specification Zrea$sD an aircraft don into its systems; etc..; such as airconditioning; electrical poer and landing gear; and then allocates these systemschapter numers. Thus; air conditioning is Chapter 21K electrical poer; Chapter24K and landing gear; Chapter 32. The )arious system chapters are arrangedalphaetically; there eing no natural order of precedence or importance.

& feature of the Specification is that here applicale the )arious Chapter

6umers are the same in all the manuals. Thus; information on the landing gearis found in Chapter 32 in the 8aintenance 8anual; in the /iring :iagram8anual; in the )erhaul 8anual and in the Illustrated Parts Catalogue. Should ite necessary to issue a Ser)ice "ulletin referring to the landing gear; the ulletinould carrying the prefi- Z32D. +uselage structure data; co)ered in Chapter 3; isfound under Chapter 3 in the 8aintenance 8anual; in the Illustrated PartsCatalogue and in the Structural Repair 8anual.

8ost systems are too comple- to e co)ered in one go; and accordingly &T&Specification 1 pro)ides for such systems to e sudi)ided. Thus; landinggear is descried generally and then di)ided into main gear and nose gear. Thegeneral description is referenced 320; the su0systems eing allocated the

numers 3201 and 3202; respecti)ely. Some su0systems may e sufficientlycomple- to re7uire further sudi)ision. Thus Zmain gearD could e ro$en doninto main leg; side stay assemly; the fairlings; these eing allocated referencenumers such as 3201011; 3201021 and 3201031 respecti)ely.

The )erhaul 8anual referred to pre)iously contains information on componentsdesigned and manufactured y the aircraft manufacturer. )erhaul informationon other components and on the engines is produced y the )endors and enginemanufacturer.



A.T.A.1)) CHAPTER #REAKDOWN

C:+7te/ T*t,e Coe C:+7te/ T*t,e Coe

,7uipment 5ist 3 -ygen . a c d

!:imensions areas

a 3! Pneumatica c d

% 5ifting Shoring a 3' /ater @ /aste a c d

'5e)elling /eighing

a 4* &irorne &u-iliarypoer

a c d

* Toing Ta-ing a 1 Structure 0 General a e

1 Par$ing 8ooring a 2 :oors a c d e

11 Re7uired placards d 3 +uselage a c d e

12 Ser)icing a 4 6acelles @ Pylons a c d e

2Standard practices0 &irframe

a c d Stailisers a c d e

21 &ir conditioning a c d ! /indos a c d e

22 &uto pilot >or &utoflight?

a c d % /ings a c d e

23 Communications a c d ]%Standard practices0 ,ngine

a c

24 ,lectrical poer a c d ]%1Poer plant 0General

a c d

2,7uipment @+urnishings

a c d ]%2 ,ngine a c d

2! +ire protection a c d ]%3

,ngine fuel

control a c d

2% +light controls a c d ]% &ir a c d

2' +uel a c d ]%! ,ngine controls a c d

2* 9ydraulic poer a c d %% ,ngine indicating a c d

3Ice rainprotection

a c d ]%' ,-haust a c d

31 Instruments a c d ]%* il a c d

32 5anding gear a c d ]' Starting a c d

33 5ights a c d ]'2 /ater in<ection a c d

34 6a)igation a c d *1 Charts a

34 0 GP/S

CodeJ a. 8aintenance 8anual

. /iring :iagram 8anual

c. )erhaul 8anual

d. Illustrated Parts Catalogue

e. Structural Repair manual

] Issued in part or complete y the engine manufacturer.



A.T.A.1)) PAGE #LOCK #REAKDOWN

,ach chapter of the manual is further su di)ided y page as follos

• '+*nten+ne '+n+,

:escription and operation .............1 to 1

Troule shooting ...........................11 to 2

8aintenance practice ....................21 to 3

r here comple-J

Ser)ing..........................................31 to 4

Remo)al@Installation .....................41 to

&d<[email protected] to !

Inspection@Chec$...........................!1 to %

Cleaning@Painting ..........................%1 to '

&ppro)ed repairs ..........................'1 to *

• W*/*n0 D*+0/+6 '+n+,

Routing charts >:iagram? +ig.1 to 1

Theoretical >schematics? +ig.11 up

• Oe/:+, '+n+,

:escription; operation and data .. .1 to 1

:isassemly ................................11 to 2

Cleaning ....................................21 to 3

Inspection@Chec$ ........................31 to 4

Repair .........................................41 to

&ssemly ...................................1 to !

+its and clearances ....................!1 to %

Testing ........................................%1 to '

Troule shooting .......................'1 to *

Storage instructions ....................*1 to 1

special tools; fi-tures ande7uipment ....................................11 to 11

Illustrated parts list .......................111 to 12

+or simple units; pages are numered consecuti)ely; ith paragraphs numered1 to 12 corresponding to the ao)e rea$don.



1".1.1.1 Csto6*s+t*on +n e@@et**t-

&ircraft ha)e different e7uipment fitted and are at different modification states;therefore a single manual cannot apply to all aircraft; not e)en to all aircraft of thesame type. The differences in specification are catered for y customising themaintenance documentation. Customisation is limited to theJ

• 8aintenance 8anual

• /iring :iagram 8anual• Illustrated Parts Catalogue

• )erhaul 8anual

• +ault rectification or Isolation manuals e-ist in customised and nocustomised )ersions.

& non customised document ill apply to all aircraft produced y a manufacturer.

& customised document co)ers all of the aircraft ithin a customerFs fleet; or all ofthe aircraft ithin a poolFs fleet.

/hen the information in a manual is not applicale to all aircraft; the pieces of

information are grouped in paragraphs of e@@et**t-. The effecti)ity is generallyshon at the ottom of each page of each manual and is indicated y customeror pool fleet numers; aircraft registration numers or a manufacturers serialnumer.

It *s essent*+, t:+t t:e e@@et**t- *s :ee hen carrying out maintenanceor$ of any description on an aircraft. There may e se)eral pages one after theother in a manual; each page loo$ing similar to the one in front; ut only onepage may apply to the aircraft eing or$ed on.

The statement of effecti)ity is included in the introduction to each manual.

1".1.1.2 S7e*+, 6ent*on

&lthough you should ta$e e)ery opportunity to ecome totally con)ersant ith allmaintenance documentation in all formats; some manuals arrant specialmention at this stage. This should e ta$en as an indication of the importance ofthese manuals to your daily or$.

1!.1.1.2.1Component 5ocation 8anual

The component 5ocation 8anual >C58? follos the same chapter rea$don asthe 8aintenance 8anual and lists all functional systems ith their respecti)elocations and access doors. ,ach component is identified y an electrical ormechanical identifier and a designation.

1!.1.1.2.28aintenance 8anual Standard Practices

&s e ha)e seen the 8aintenance 8anual >88? is di)ided into chapters andeach chapter is further di)ided into page groups. The maintenance manual is theasic document for all information concerning maintenance procedures.

The chapters containing st+n+/ 7/+t*es +/e ons*e/e to e t:een0*nee/s #*,e. They comprise 3 main oo$sK Standard Practices &irframe 0Chapter 2; Standard Practices ,ngine 0 Chapter % and Standard Practices &)ionic; contained in Chapter 2 of the /iring :iagram 8anual. It is not possileto detail all the information contained ithin these three manuals; therefore YOU'UST E9A'INE THESE 'ANUALS YOURSELF AND #ECO'E FULLYCON(ERSANT WITH THEIR CONTENTS.



1!.1.1.2.3Illustrated Parts catalogue

The illustrated parts catalogue is used for the identification and pro)ision ofreplaceale aircraft parts and units. The IPC is a companion document to the 88and includes all parts for hich maintenance practice has een pro)ided.

Guidance on the use of illustrated parts catalogues is gi)en in the introductionchapter of the manual. Yo =*,, e e7ete to e +,e to se t:*s 6+n+, to*ent*@- 7+/t n6e/s; this can only e achie)ed through practice.

1!.1.1.2.4+ault Isolation 8anual

The +ault Isolation 8anual >+I8? is a ground manual alloing the maintenanceengineer to perform 7uic$ troule shooting and to determine hich linereplaceale unit >5R#? is faulty. This manual as designed to reduce the Zdontime Z of aircraft; hoe)er it should e noted that it ill not >in the foreseealefuture? replace the e-perienced engineer. n occasions the manual can emisleading and can result in the replacement of ser)iceale components ore7uipmentDs. To use the manual properly; one needs a good understanding ofthe system under test.

This manual is effecti)ely eing uilt into modern aircraft and e7uipmentDs.

&ircraft continually monitor and test themsel)es; should a fault condition arise the5R# at fault is normally identified y the automatic test procedure and displayedor stored for later identification.

1!.1.1.2./iring diagram manuals

The iring diagram manual is the asic document concerning electrical systeminformation; it containsJ

• The electrical and electronic loc$ and iring diagrams

• The list of cales and connectors

• The iring repair procedures

:iagram numering is in accordance ith &T& specification 1. ,ach diagram isassigned a page numer. /hen only one configuration of a diagram e-ists; it ille page 1; hen different configurations of the same system e-ist; they ill ereflected on page 2; 3 etc.

/hen a diagram is referenced to another; only the diagram numer is used.Therefore; hen there is more than one page of the same diagram; it isnecessary to refer to the effecti)ity loc$ to ma$e certain the diagram applies tothe aircraft of interest.

If diagrams of the same circuit cannot e shon on one sheet; they are shon onadditional sheets; ha)ing the same title and diagram numer. These additional

sheets are identified as sheet 2; sheet 3 etc.C:+7te/ 2) o@ t:e WD' *s t:e +*on* en0*nee/s 7/*6+/- so/e o@*n@o/6+t*on @o/ ALL st+n+/ 7/+t*es se on t:e +sso*+te +*//[email protected] IT +n LEARN HOW TO USE IT. ,-cellent guidance on its use isgenerally pro)ided in the manual.



1".2 LIGHT AIRCRAFT 'ANUALS

The &T& specification 1 is generally used for all large commercial aircraft;hoe)er it is not a legal re7uirement; ut simply an international agreement. Thisagreement does not e-tend to smaller aircraft. The much smaller scale ofoperation does not arrant the use of such systems and therefore indi)idualcompanies are left to their on de)ices. This results in a )ariety of differentformats and )ariations in the le)el of information or detail pro)ided. In the orstcase; the only information gi)en for maintenance procedures are e-pected )alues

or tolerances; the procedure is left to the engineerDs e-perience.



1!. CIRCUIT SY'#OLS

The folloing circuit symols ha)e een ta$en from a typical aircraft manual andare intended to e a small selection of hat you ill find eing used in aircraftmaintenance documentation. Bou ill e e-pected to memorise commonsymols; as ithout them you ill e unale to negotiate the aircraft schematicdiagrams and iring diagram manuals. This applies irrespecti)e of your intendedtrade.

+or manuals produced i.a.. the &T& specification 1; a list of circuit symolscan e found in the /:8 Chapter 2. +or other aircraft no such list may e-istand you ill ha)e to rely on memory.

mod 7 maint pract

Documents