previous page table of contents next page · previous page table of contents next page. do be sure...

Previous Page Table of Contents Next Page

VOL. 1, NO. 2, APRIL ·JUNE 1974

A SERVICE PUBLICATION OF LOCKHEED OEORQIA cor.IPANV. A OJVISION OF t.OCKflEto AIRCRAFT CORPORATION

A SERVICE PUBLICATION OFLOCKHEED-GEORGIA COMPANYA DIVISION OFLOCKHEED AIRCRAFT CORPORATION

EditorJay V. Roy

Associate EditorJames A. Loftin

Art Direction & ProductionPhillip E. Evans

COVER: A unique picture of the first commercialHercules which was later to become the first -20 model(100 in fuselage extension ) This aircraft i s now in servicewith the Philippine Air Force

COMMENTS

Our first issue has received some finecomments, which we appreciate verymuch. We believe you will find thissecond issue to be even more useful. Wehave tried to provide something ofinterest for everyone - including anarticle on our Standardized LogisticsManagement System.

If you have suggestions, criticisms,comments, wish to be put on distri-bution, or need additional copies, pleasecontact your Field Service Repre-sentative or send us a note addressed:

Editor, Service NewsLockheed-Georgia CompanyMarietta, Georgia 30063U.S.A.

Published by Lockheed-Georgia Company, a Division ofLockheed Aircraft Corporation. Information contained inthis issue i s considered by Lockheed-Georgia Company tobe accurate and authoritative; it should not be assumed,however, that this material has received approval from anygovernmental agency or military service unless it isspecifically noted This publication i s for planning andinformation purposes only, and it i s not to be construedas authority for making changes on aircraft or equipmentor as superseding any established o p e r a t i o n a l o rmaintenance procedures or policies The following marksare registered and owned by Lockheed AircraftCorporation “ ", “Lockheed”, “Hercules”, and“JetStar”. Written permission must be obtained f romLockheed-Georgia Company before republishing anymaterial in this periodical Address all communications toEditor Service News Department 64.22, Zone 278,Lockheed-Georgia Company, Marietta Georgia, 30063Copyright 1974 Lo&heed Aircraft Corporation.

VOL. 1, No. 2, April-June 1974

CONTENTS

3

7

9

12

Hercules Propeller Control Oil Level CheckUsing the Atmospheric Sump Dipstick

The Standardized Logistics Management SystemA Better Way to Maintain Any High Technology Product

Hercules Wire IdentificationIncluding a Cross-Reference Chart

Steel Cylinders for the JetStar MLG ActuatorsYou Can Install These Preferred Spares

StarTips6 A Quick Way to Drain Hercules Aux Tanks

11 How to Bleed a Hercules Hydraulic Pump - and Keep It Clean


Checking the Hercules propeller control oil level may appear, at firstthought, to be a simple matter. However, improper checking continuesto be the cause of many propeller problems.

To make oil level checking easier and more accurate, an atmosphericsump dipstick has been added to the pump housing assembly. The 3atmospheric sump dipstick is in addition to the original pressurized sumpdipstick. It can be retrofitted by Hamilton Standard Commercial ServiceBulletin HS Code 54H60 No. 39 or Military ECP. Most late modelHercules aircraft incorporated this improvement during production.Figure 1 shows this configuration.

It is possible that an aircraft may have both configured pump housingsinstalled, especially if one or more of the originally delivered propellershas been replaced. That is, one prop with an atmospheric sump dipstickand the others without - or any such combination.

ATMOSPHERIC SUMP DIPSTICKHow does the atmospheric sump dipstick give an easier and moreaccurate oil level check? Let us look at the propeller control oil systembriefly. There are two oil reservoirs - the pressurized sump and theatmospheric sump.

The PRESSURIZED SUMP is the reservoir for the main, standby, andauxiliary pumps; and is pressurized at 15 to 20 PSI to prevent cavitationof the pumps at altitude. Hydraulic pressure for the pitch changingmechanism is provided by the oil (under control of the valve housingassembly) supplied by these pumps. This oil, except for the portion usedfor lubrication and that involved in internal leakage, returns to thepressurized sump. The portion of oil that is utilized for lubrication or isinvolved in internal leakage drains into the atmospheric sump along withthe excess fluid from the pressurized sump.


The ATMOSPHERIC SUMP is the reservoir forthe main and auxiliary scavenge pumps. Thesepumps replenish the pressurized sump with oilunder pressure to maintain the 15 to 20 PSIpressure in the pressurized sump. In order for thescavenge pumps to perform properly, the oil levelin the atmospheric sump must stay within acertain range. If the oil level is too low, aninadequate oil level in the pressurized sump willresult and the scavenge pumps will cavitate,thereby introducing air into the oil system. If theoil level is too high, the elevated oil level andnormal pump action result in lip seal damage andsubsequent lip seal leaks.

This range is reflected on the atmospheric sumpdipstick’s lower markings (refer to Figure 2),consisting of an upper mark, a legend - “OPLEVEL,” and a lower mark. If the oil level isanywhere between these two lower marks, thereis a sufficient quantity of oil. This featureprovides flexibility in refilling, reduces thechances of overfilling; and, if the control isproperly serviced, assures that the scavengepumps are provided with the right amount of oil.

4 With the pressurized sump dipstick, one has tocontend with adding small quantities of oil atmore frequent intervals, and it cannot bedetermined how much reserve is in the atmos-pheric sump. Do not be concerned, though, ifthis is the version you have. Just follow theprocedures contained in the applicable main-tenance and servicing publications.

NOTE: The following is used for informationpurposes only. Use your own approvedprocedures for actual servicing.

SERVICINGFirst assure that the propeller control oil iswarmed to its operating temperature - either bywarm air or by running the engine; then cycle thepropeller from ground start blade angle to featherand back to ground start blade angle. Now wecome to the difference between the two checks.

PRESSURIZED SUMP DIPSTICK CHECK -Wait two minutes, carefully unlock the oil fillercover (or you might get a face full of oil), removethe dipstick and check the oil level. If indicated,add the required amount of oil, recycle the prop,and recheck the oil level.

FIGURE 1Top picture looks down on a propeller control unit that does not

have the atmospheric sump dipstick. At bottom is a closer view of

a recent unit showing dipstick handles for both atmospheric and

pressurized sumps. The pushbutton for the flexible atmospheric

sump dipstick appears just above the open port to the pressurized

sump.

ATMOSPHERIC SUMP DIPSTICK CHECK -After cycling the prop, bring it back to GROUNDIDLE (GROUND START for commercial) andremove the dipstick (see note) while the auxiliarypump motor is still running. Why? Because youwant to check the atmospheric sump oil levelunder operating conditions, and this is what theauxiliary pump is simulating. Its associatedscavenge pump is supplying the pressurized sumpand generating a certain amount of agitation tothe oil in the atmospheric sump. As we pointed


out before, if the oil level is anywhere betweenthe two lower marks - this is satisfactory.

NOTE: Take all oil level readings with dipsticklocking balls seated on counter boreshoulder in tube. Do not depress ballplunger to allow dipstick to lock inplace when taking readings.

If the level is at, or near the lower mark, add oilas necessary. If it is above the upper mark, drainthe oil until it falls within the two marks.

Be sure to run the engine, cycle the prop, andcheck the level again before draining oil.

OVERFILLINGMaintaining the proper oil level is very impor-tant. Low oil level can result in having to feathera prop and shut down an engine at a criticalmoment such as takeoff. Most propeller pro-blems are less dramatic, but costly in time andmoney. A very common problem is overfilling.If there is too much oil, it will be forced outaround the prop control lip seals. This will leadto lip seal damage and also show up as a propelleroil leak.

Now let us suppose that this leak is noticed on apreflight inspection by a crewman who is underpressure to get the airplane in the air. Thegentleman in question, being in a hurry, wipes itup and checks the oil level. He then compoundshis problem by not running the engine, or evencycling the prop. The pressurized sump hasleaked down a bit, so he adds more oil - whichends up in the already overfilled atmosphericsump. (This would have been detected with anatmospheric sump dipstick). The aircraft takesoff, and more oil is forced out around the prop 5

control lip seal.

At one of the next inspections it is necessary topull the leaking control and replace seals.Farfetched? Not at all. This has happened, orincidents similar to it, all too often. That is oneof the reasons why the atmospheric sump dipstickhas been added. Overfilling has been one of themajor causes of unscheduled prop removal andoverhaul.

NOMENCLATUREWe would like to clear up some confusion whichmight exist in terminology:

Feathering Pump and Auxiliary Pump - they arethe same pump.

Oil Reservoir - it can be either the atmosphericsump or the pressurized sump, depending uponthe one you are servicing,

DO’S AND DON’TSDO become familiar with the procedures specifiedin your applicable maintenance/servicing publi-cations, and follow them.


DO be sure the oil is at, or near, operatingtemperature before statically changing the bladeangle, especially if the propeller has been exposedto temperatures of O°C (32 F) or below.

DON’T overfill the propeller control. Drain ifnecessary.

DON’T run the auxiliary pump longer than itsrated duty cycle. (You can run i t longerproviding you can hold your hand on it for 5seconds or longer - approximately 150 F - butmonitor it closely.)

DON’T let any precipitation or other foreignmatter get into the oil filler ports.

DO run the engine before checking the oil,especially if the aircraft engine has not been runfor two days or more.

DO make a thorough visual inspection of thepropeller control.

DO use only the proper oil. MIL-H-5606B ispreferred, but MIL-H-6083 can be used. Thelatter contains a preservative and tends to turndark with use.

6 DON’T let oil spill on electrical contacts orde-icer slip rings; but if this happens, cleanthoroughly to prevent future electrical problems.

DO check at regular intervals. Hamilton Stan-dard’s Operation and Maintenance InstructionManual (P5059) for the Commercial Hercules -91and -117 props recommends you check the oillevel at a period not exceeding 60 flight hours, orweekly.

To conserve fuel, try to check the oil level on thelast postflight inspection while the oil is stillwarm and the pressurized sump is still full. Thiswill save starting up four engines and runningthem for 10 to 12 minutes each to warm up theoil the next morning.

In closing, just remember to follow the applicableprocedures, mainta in i t proper ly , and thepropeller should give many hours of trouble-freeservice.

QUICK WAY TO DRAINHERCULES AUX TANKS

by P. R. L a M o n s Service Analyst

If you work on Hercules’ that have the newbeefed-up center wing section, you may know it’shard to empty the auxiliary fuel tanks quickly ifthe pump happens to quit with the tanks full offuel. Lockheed has developed a simple tool todrain the aux tanks four or five times faster thanyou could using a pogo stick (see drawing). Tomake it, get yourself a short piece offive-eighths-inch OD pipe with standard threads.Drill four three-sixteenth-inch holes in the threadsone-quarter inch from the end. Clamp a hose onthe other end. Now, remove the center core ofthe airplane’s “jiffy” drain with a wide bladescrewdriver, and the small pogo plunger will failout.

Next, screw the five-eights-inch pipe into thedrain where the center core was removed until thepipe opens the jiffy drain valve. Be sure the hoseis clamped shut while the pipe is being put inplace because when fuel flow starts, it won’t stopuntil the tanks are empty. Remove the drainadaptor and re-install the pogo plunger and jiffydrain center core.


THE STANDARDIZED LOGISTICS MANAGEMENT SYSTEM

R. E. AycockData Processing Systems Group Supervisor

V. W. ValentineManagement Systems Development Analyst

During the 22 years that the Lockheed-Georgia Companyhas manufactured aircraft and other high technologyproducts, it has been necessary to develop a formidablecapability in computing and data processing. Thiscapability is now directly available to users of theHercules.

In 1973 we developed the general specifications for afamily of five data processing systems designed to assistC-130 operators in the control of spare parts inventory,procurement of spare parts, and maintenance of theirHercules. These systems are designed to support any typeof airplane and can even be used to control and procurematerial not related to aircraft. All five systems performthe same basic functions but differ in complexity andprocessing techniques. This article describes the “middle”member of the family, Mark 3, which uses sequential filesand can be implemented on a small or medium-scaledigital computer or in one partition of a large, timesharing computer.

SLMS-MK 3 provides its user with an orderly approach toautomating vital logistics management functions; it assistsin keeping the user’s fleet and major items of supportequipment in a mission-ready condition; it helps to assurethe availability of spare parts with the most economicalordering condition; it helps to assure the availability ofspare parts with the most economical ordering intervals,thus minimizing capital investment; and it helps to assureflight safety and aircraft technical adequacy by managingspecific maintenance tasks and requirements.

INVENTORY CONTROL SUBSYSTEMThe Inventory Control Subsystem is the heart ofSLMS-MK 3. It:

Determines economic quantities of materials and spareparts to be procured and provides planned orders.Determines and assists in maintaining optimuminventory levels of spare parts and materials, andassists in storing and locating them.Shortens time spans required for procuring spare partsand materials.Provides usage, shelf life, and other historical data forthe manager and for the Procurement and Main-tenance Subsystems.’Provides appropriate reports for management.Provides the basis for financial control. 7

Utilizing factors input by the Logistics Manager,SLMS-MK 3 computes the economical order quantity.Each time disbursements are recorded, the balance onhand is checked and, if below a prescribed point, apotential reorder is evaluated. If the evaluation warrants,a request to procure is sent to the appropriate LogisticsManager for the necessary actions.


PROCUREMENT SUBSYSTEMThe SLMS Procurement Subsystem provides:

Assistance in controlling financial commitments.Timely information on critical and long lead timeitems.Assistance in following up on delinquent purchaseorders.

Purchase orders and amendments to purchase orders arethe media used to procure spare parts and materiel. Therequirement for the spare parts must be determined andproper authority obtained to begin the procurementcycle, In SLMS the initiation of the procurement cycle ismade in the Inventory Control Subsystem. How much toorder and when to order it are computed, and appropriatedocumentation is issued. The documentation is apreprinted request, which must then be validated by aLogistic Manager. When the need to procure has beenformally translated and validated, the usual sources andcontacts established by the user will be followed. SLMSdoes not interfere with the user’s customary methods ofdealing with vendors.

THE MAINTENANCE SUBSYSTEM

The SLMS Maintenance Subsystem provides:Means to preplan inspection workloads and reducespares in pipeline.

Inspection schedules and assurance of mandatorycompliances.

8 Reports on aircraft which require parts, kits, specialtools for compliance.

Historical data for performance, reliability, and trendanalyses.

Effectiveness and economy in mission performancedemand that maximum maintenance be performed at thelowest practical organizational level. The use ofmanpower, equipment, and facilities are normally basedupon this principle. The SLMS-MK 3 has been designedto collect data in four areas which are important to theachievement of this goal: Component Repair Control;Modification Control; Time Change Control; Scheduledand Special Inspection Control. maintenance Control,Quality Control, and other dispatch of scheduling aspectsof maintenance may be included within the SLMS-MK 3Maintenance Subsystem after implementation, with thebuilt-in flexibility provided initially.

COMPONENT REPAIR ACTION CONTROL - A largepercentage of a maintenance organization’s resources isused to repair aircraft systems, subsystems, andcomponents. Management must have information feed-back from these repairs.

In SLMS-MK 3 all maintenance jobs are recorded so thatcomprehensive data are available for analysis of failurerates versus equipment operating time; malfunctionsrelated to inspection intervals; and reliability expectationsfor systems, subsystems, and components.

MODIFICATION CONTROL - Modifications are usuallythe result of changes or alterations to missionassignments, conditions for safety, and operationalenvironments. It is essential that adequate records bemaintained for each modification, so that the currentstatus of each piece of equipment assigned to anorganization is known at all times. SLMS-MK 3 will helpmaintain this status.

TIME CHANGE CONTROL - Certain parts or com-ponents installed on aircraft or other equipment must beoccasionally removed for inspection or overhaul at theexpiration of specified operating hours, landing gearcycles, days, or dates. These removals and related work,known as Time Changes, can generally be forecast in timeto permit Inventory Control to review available assets andtake action, if necessary, to meet the requirements.

SCHEDULED AND SPECIAL INSPECTION CONTROL- All equipment must receive repetitive inspections ofsufficient thoroughness to verify serviceability or todetect deficiencies and malfunctions. Inspections arerecurring, and compliance with the inspection require-ments is normally mandatory. SLMS-MK 3 thereforemaintains an accurate accounting of what inspections arerequired, when the inspections are due, when inspectionshave been accomplished, and an evaluation of whetherequipment is being over-inspected.

IMPLEMENTATIONThe Lockheed-Georgia Company believes that thecapabilities of SLMS-MK 3 can play an important role inlogistics management, and that its implementation byHercules users can result in cost-effective logisticsmanagement. Implementation of SLMS-MK 3 is begun bya study, performed by representatives of theLockheed-Georgia Company within the user’s country atthe locations where the system will be implemented, toadapt the general specifications to the user’s specificrequirements. This first phase lasts about 90 days.

After this study or adaptation phase, implementation isaccomplished with the analytical and programmingresources of the user, of the Lockheed-Georgia Company,or of both. Lockheed-Georgia is prepared to implementSLMS-MK 3 totally, but it may be more economical totake advantage of the user’s resources. Implementation,which might take nine to twelve months, is accompaniedby appropriate training and familiarization with inputforms, procedures to be used, and the outprovided at the user locations by LockheedCompany representatives.

put reports, all-Georgia

describingFor further information and a brochureSLMS-MK 3, contact:

E. W. HerronDirector of Information ProcessingD/87-01, Zone 514Lockheed-Georgia CompanyMarietta, Georgia 30063


by JACK ATKINSON,COMPONENTS ENGINEER SENIOR

Sometimes the job of replacing adamaged Hercules wire involves morethan removing one part and installinganother. In some cases a damagedwire to be replaced is identified onthe wiring diagram by a Lockheedspecification or a supplier number,and the technician cannot identify orassociate this wire with a militaryspecification, or standard, or anequivalent supplier number withwhich he is familiar.

Usually, he contacts the LockheedField Service Representative, who canprovide the information for him.Several alternatives may be offered.When the advice is conveyed back tothe technician he may find that wirefor replacement is at his own facility.

Maybe this has happened to you. Solet’s review the most commonly usedHercules electrical wire and cable. Ona following page is a table that showsequivalent and superseded callouts aswell as adequate replacements.

Most of the wire listed in the table isstandard airframe material; so, if thetechnician knows what the wire is, hecan often make his own decision, intime of emergency, as to whatsubstitute can be used. Let’s look atsome of the wire types.

PROPELLER HARNESSThe wire used in propeller harnessesin the engine nacelle is enclosed instainless steel conduit and asbestossleeving since these harnesses areexpected to function for a shortduration in case of an engine fire.The specification called out on mostexisting diagrams for the wire isMIL-W-7139. Newer design diagramscall out MIL-W-22759/1. Both ofthese specifications cover wire con-sisting of a silver coated copperconductor and TFE-Teflon primaryinsulation which may be taped orextruded. There is a layer of treatedglass tape, or an additionalTFE-Teflon tape. The outer coveringis a TFE-Teflon coated glass braid.This wire is good for 2OO C (392 F)continuous conducter temperature.

GENERAL PURPOSE WIREThe most widely used wire on theHercules is called out as LAC 1-140dby the majority of existing wiringdiagrams. This wire is basicallyMIL-W-5086/2A which is being speci-fied on new design wiring diagrams.It is a general purpose wire that isinsulated with polyvinyl chloride(PVC) and glass braid. It has a nylonjacket which is extruded on sizesAWG 22 through AWG 12 andbraided for larger sizes. The braidedjacket is saturated with a nylonlacquer which seals the braid. Thiswire is used in areas throughout theairplane where the conductor temper-ature is not expected to go above105 C (221 F).

The most widely used shielded wire orcable is called out as LAC 01-2049which is basically MIL-C- 7078/3which is being specified on new designwiring diagrams. This cable consistsof MIL-W-5086/1 as the basic wireshielded with tinned copper braid andcovered with a nylon jacket.

FUEL QUANTITY WIREAND CABLEAll wire and cable used inside the fueltanks is Teflon-insulated. The hook-up wire is MS 18000, which hasmineral-filled TFE-Teflon, and thecable is Lockheed specification LAC01-2031, which is a TFE-Tefloninsulated wire that is shielded andjacketed. The shield is a nickel-platedcopper braid and the jacket isextruded FEP-Teflon. Outside thetanks, conventional hook-up wire isused. The cable outside the tanks isprimarily LAC 01-203 1; however, insome installations Surprenant No.4987 is called out. It is polyeth-ylene-insulated and nylon-jacketed.The Teflon-insulated, fuel-resistantwire and cable may be used outsidethe tanks.

ENGINE WIREThe standard wire for the engine areais MIL-W-8777, which has a silver-plated copper conductor and siliconerubber primary installation. Over theprimary insulation, there is a glassbraid and then a Dacron braid which


(Specification or vendor number)

MI L-W-22759/1

LAC 01-2032A or later

MIL-W-7139

Packard PE 400

warren ww 400. ww 500

MIL-C-27500 (*) H (**)S5

L A C - l - 1 3 8

LAC -01.138

Prop control harnesses

Shielded and jacketed

engine area wire

MIL-W-7139A

MIL-W-7139B Class lMl L-W-22759/1 or /2

LAC 01-137

MIL-C-27500(*)E(**)S4 or S5

(*)EA(* *)S4 or S5

(*)D(**)S4 or 5

(*)N(**)S5

(*)F(**)S4 or5

(*)RB(**)S4 or 5

MIL-C-27500(*) RB (**) S5

LAC 1-137

LAC 01.137

LAC 01-159

AF 32659

L A C l - 1 1 0

LAC 01.110

Shielded and jacketed

medium high temperature

Fire zone wire and cable

MIL-C-275OO(*)E(**)S5

(*)EA(**)S5

(*)D(**)S5

(*)N(**)S5

MIL-C-25038

MIL-W-25038

MS 27125

LAC 01-2033 Type IType II Fire zone wire and cable For Type

I Only

LAC 01.159

MI L-C-25038

MI L-W-25038

MS 27125

MS 18000

ITT (Surprenant)SAKF728A

Minn.-Honeywell 6816 -3

LAC 01-2035

Fuel quantity hook-up wire

Type II MIL-C-27500 (*)JA(**)N7

Ml L-W-22759/7 or

10

Ml L-W-8777Engine wire and medium

high temperature applications

MIL-W-7139A

MIL-W-7139B Class I

MIL-W-8777 A or B

MIL-W-22759/1, /2, /3 or /4

MS 2547 1

MS 27110

MS 90294

LAC 01-2031 Rev. G3

LAC 01-2031 Rev. G1 & G2

L A C 01-2031A

ITT X - 1 2 1 0 9

CBB 59Y AAA

12258

1272 -2

1934 TX2801 SJ

Fuel quantity cable

Best to use only that which is

called out or the superseded

cable es shown.

Surprenant No. 4987

(ITT)

Ml L-W-5086/2 (M 5086/2)

L A C l - 1 4 0

LAC 1-140a. b, c, d

L A C 1-166a

Rockbestos RSS 48A

Fuel quantity cable -

outside tanks only

General purpose interconnecting

wire used throughout airplane

LAC 01-2031 Rev. G 1,

G2 or G3

LAC 01-140

MlL-W-5086A Type I or I I IMI L-W-7139A

MIL-W-7139 B Class I

MIL-W-8777 A or B

MI L-W-22759/1, /2, /3 or / 4

MI L-W-81044/2,/6 or /9

MS 25190 Type A or 8

MS 25471

MS 27110

MS 90294

Ml L-C-7078/3 (M 7078/3) LAC 01-137

LAC 01-2049 General purpose shielded LAC 01-138

LAC 01-136 wire used throughout airplane MS 25192 LAC 01-135 MIL-W-7078A Type II LAC 1-135a, or b MIL-C-2750O(*A)(**)T2

NOTES:(*)D(�)S5

(*)H(**)S4 or 5The applications shown above are for general identification only and by no means are complete. (*)F(**)S4 or 5All materials listed under �adequate replacement� are considered functional equivalents or better. (*)N(**)S5

Cost. weight. size and appearance may vary for these materialswhen compared with original callouts. (*)MA(**)SS,T8, 513, orT13

*AWG Number (*)ME(**)S8,T8,S13, orT13

**Number of wires (*)MH(**)SB.T8,S13. orT13

Indicates superseded Lockheed procurement callouts that remain on many existing drawings.


are saturated with a lacquer. The wireis good for conductor temperaturesup to 2OO C (392 F). This same wireis also used with a silver-platedcopper-braided shield and a jacket ofbraided Dacron saturated with lac-quer. The shielded version is identi-fied as LAC 01-138 on most existingdiagrams and MIL-C-27500 ( )H( )S4on new design drawings. Wire toMIL-W-8777 and MIL-C-27500( )H( )S4 are also used in other areasof the airplane for isolated appli-cations.

FIRE ZONEThe wire used in fire zone appli-cations is identified as LAC 01-2033or LAC 01-159 and consists of nickel-clad copper conductor insulated withasbestos, glass tape and outer glassbraid with a TFE-Teflon resin finish.This wire is basically MIL-W-25038;however, Lockheed specifications re-quire an extended flame test. There-fore, the wire exceeds the military

requirement. Fire zone wire is goodfor continuous operation at tem-peratures of 342 C (650 F) and for5- to 15-minute duration in a 1093 C(2000 F) flame. In many appli-cations where the normal temperaturenever exceeds 149 C (300°F), nylon-jacketed LAC 01-2033 Type I wire isused.

In case of fire, the nylon jacket willburn off, leaving the basic wire intactsince the nylon jacket was added formechanical protection only. Quiteoften the nylon jacket of LAC-01-2033 is damaged, but this doesnot alter the functional capability ofthe wire. Therefore, it is notmandatory to replace the wire unlessthe insulation of the basic wire isdamaged. For applications where thenormal temperature exceeds 149 C(300 F), LAC 01-159 is used.

HOW TO BLEED A HERCULES HYDRAULICPUMP- AND KEEP IT CLEAN

by FRED HEHMEYER Service Representative

You don’t have to put up with hydraulic fluid allover when you bleed Hercules engine-drivenhydraulic pumps at the nacelle bleed fitting. Gothis cleaner route instead:

Fill and check the fluid level in the reservoir, thenwith a-c ground power plugged in, turn the utilityand booster system suction boost pumps “on.”Assuming you’re bleeding the number one enginepump, first switch the number two pump “off.”(If it’s number four, turn off number three, andso on.)

Now cycle the aileron controls 25 times. Fluidmoving through the system will automaticallyexpel air from the line as it comes back around tothe reservoir. Top off the reservoir, reset allswitches back to “normal,” and you’re clean forthe next flight.

11


WHICH IS BETTER, aluminum or steel, for anairplane part? The answer to that is not alwaysobvious. Both are used. Aluminum is lighter.Steel is stronger. There are many othercharacteristic advantages in each of these metalalloys. In some applications, the trade-offs makethe choices about equal. In some cases, a betterchoice is apparent only after several years ofoperations.

We now know that steel is preferable material forthe cylinder, or “barrel”, in the actuating cylinderside brace assemblies that retract the main landinggear on the JetStar. If you have not already doneso, we recommend that you update youractuating cylinders with this preferred spare assoon as practical.

At overhaul, the aluminum cylinders are beingreplaced by steel at the customer’s option. ManyJetStar Owners are updating their own earlier byordering the cylinders and repack kits fromLockheed and replacing the aluminum cylindersat their maintenance facilities, This replacementdoes not postpone overhaul. If less than 10% ofthe time between overhaul remains on yourlanding gear actuators, you may want to sendthem on to an authorized overhaul facility for the

complete job.

If you buy the actuators assembled, and theyhave been in storage, you may want to be certainthat all seals and packings are functioning

properly, and that the downlock swi tch iscorrectly adjusted. Refer to the functional andswitch test instructions given later in this article.

TO UPDATE both of your main landing gearactuating cylinders you need two new steelcylinder barrels (part number each P/N JL 140 l-2)and two repack kits (part number each P/NJSK604-2). These parts are the same for right orleft assemblies. The drain holes in existing endcaps make them different for right and leftassemblies. Other right and left parts are theswitch adapters and locking arms.

Repacking this actuator is about the same as forany comparable hydraulic unit of a system usingfluid to specification MIL-H-5606 operating at3,000 PSIG. All of the preformed packings and

, seals have standard part numbers. There is a newpreferred part for the shaft seal, identified on theblueprint as P/N 222 FT-160A-T.

This “T” shaped preformed rubber ring isinstalled with two teflon backup rings, one ineach recess of the seal. The stem of the seal is incontact with the shaft. This arrangement hasgreat resistance to destructive deformation of therubber imposed by the hydraulic pressure and theshaft movement.

CONVENTIONAL G-T RING

�0� RING SEAL SHAFT SEAL

A hydraulic test stand capable of up to 4,500PSIG is necessary for functional testing of thereassembled cylinders and the downlock switch.A minimum of 1,500 PSIG is necessary to operatethe cylinder while adjusting the downlockswitch. This adjustment is the last in the seriesbefore the actuator is installed. A suitable meteror light to indicate electrical continuity isnecessary to check the switch adjustment.

REFERENCESThe JetStar Handbook of Operating and Main-tenance Instruction (HOMI) a n d T . O .lC-140A-2-4 have, in their landing gear sections,the dimensions and instructions in the order oftheir adjustment. In addition, you should haveour blueprint that gives complete assemblyinstructions, as well as part numbers anddimensions. Ask for blueprint number JL1470,ACT. ASSY - MLG SIDE BRACE and send yourrequest to:

13

Lockheed-Georgia CompanyJetStar SupportDept. 64-22, Zone 287Marietta, Georgia 30063

Attn: Mr. J. R. Weiland

WE WANT TO EMPHASIZE THE IMPORTANCEOF SEVERAL REQUIREMENTS

IN ADJUSTMENTS.

DOWNLOCK OPERATIONThe landing gear downlock is inside the actuatingcylinder end cap. The importance of its function


End cap of a main landing gear actuator for the left side. T O P

view is bottom up to show drain hole near grease f i t t ing. Bottom

view shows secured downlock switch and elbow connector for the

hydraulic landing gear up l ine. The clearance shown is minimum

for installing the tubing nut.

suggests careful attention to details in reas-sembling this unit. In actual operation, the lockmechanically engages when the landing gear isfully extended, To retract the landing gear,hydraulic pressure releases the lock when theselector valve is placed in the “UP” position. Themovement of a circular piston, resembling asleeve, does the job. A spring loaded latch holdsthe sleeve in the unlocked position.

Note 13 on the blueprint is important to thefunction of the landing gear downlock mech-anism. The 1.421 inch dimension is critical totiming the release of the spring loaded lockingsleeve or slide. This sleeve moves insidemulti-finger tangs projecting from the pistonhead, after their enlarged ends snap through acircular retaining shoulder inside the end cap.This dimension is to be the final measurementfrom the tips of the fingers to the adjustable plugin the piston rod which triggers the release of thelocking sleeve or slide.

The downlock light switch is operated throughrods moved mechanically by a ridge encircling theouter end of the locking sleeve. Later, afunctional test of both the downlock and theswitch is made to check their adjustments. Thesuccess of this test depends on your accuracyfrom the beginning. Avoid remaking earlyadjustments that were just a little beyond limits.For instance, remember to maintain equal threadengagement on both ends of the cylinder insetting the 0.412 inch dimension at the shaft endof the actuator.

Anticipate the clearance you will need whenpositioning the hydraulic elbow fitting near theswitch in the end cap, because you will not haveaccess to the lock nut on the elbow after theswitch locking arm is in place. And remember,also, that the switch cannot be adjusted after thecylinder is installed on the landing gear.

Follow carefully the instructions for positioningthe switch terminals, and try the locking arm inplace to verify its position relative to the elbowand switch adapter, before you start f inaladjustments of the switch.

Check the push rod P/N JLl443-1 in the adapterhousing assembly for freedom of movement.Some of these rods have been found to fit tootight. The hole in the plug P/N JL 144 l-l shouldbe reamed to a slightly larger size in these cases.

Remember that the drain hole for the cavityunder the switch is to be down when the actuatoris installed. This means, also, that the right andleft assemblies will have the switch and hydraulicfittings at different angles.

LEAK TESTAfter the actuator is assembled and ready forhydraulic leak tests, connect the two cylinderports to the working ports of the test stand.Cycle the unit at least three times, making sure allair is bled from the system. The centerlinedimensions given on the blueprint for extendedand retracted shaft positions should be checked atthe operating pressure of 3,000 PSIG by applyingpressure alternately to each port.

Reduce pressure, then slowly apply 4,500 PSIGto one side of the piston for two minutes. Thereshould be no evidence of distortion or externalleakage. Then perform the same test withpressure applied to the other port. Internal


leakage is checked at the same proof pressure of4,500 PSIG on each side of the piston with theopposite port open. Internal leakage, measuredby catching fluid from the open port, is not toexceed 5 cc per minute.

Connect the working lines again, adjust thepressure to 3,000 PSIG, and cycle the cylindertwenty-five times to check the shaft seal.External leakage here is not to exceed one drop intwenty-five cycles.

The working hydraulic connections should remainconnected for adjusting the downlock switch. Aminimum of 1,500 PSIG is required.

SWITCH ADJUSTMENTThe downlock light switch case is about one andone half inches in diameter with a threaded stemthat screws into a bushing that adapts it to theadapter housing. The housing encloses two pushrods at a 90 angle with a triangular rockerbetween them. The housing is fastened withscrews and sealed with an O-ring against a drilledprojection on the end cap. The inner rod isactuated by the ridge on the internal lockingsleeve as mentioned previously. Check the rodsagain for freedom of movement in the adapter asthe sleeve moves.

Turning the adapter bushing adjusts the depth ofthe switch in the housing, which, in turn,positions the electric contacts in the switch toindicate the posit ion of the landing geardownlock sleeve.

With the hex jam nut threaded free on the switchstem, adjust the serrated adapter bushing to clearthe rocker housing a little more than l/16 inch

with the switch base 5/8 inch clear of thehousing. Rotate the switch to position the wireterminals at 70’ +/- 5’ from the axis of the shaft asshown on the blueprint.

The switch must be held in this position untiladjustments for electrical continuity is complete.Connect the switch lead number one to yourelectrical continuity checker and locate leadsnumber two and three for reference. Theworking hydraulic lines should be connected.The piston should be in the retracted and lockedposition.

Rotate the bushing until leads one and three areelectrically continuous. Mark or select a re-ference point on the adapter housing. Thenhydraulically unlock and extend the piston shaft.Readjust the adapter until leads one and three areagain electrically continuous, counting the serra-tions, or teeth, past a reference point. Finally,back off one half the number of teeth differencein the previous adjustment. Now check leadnumber two for continuity with number one,with the piston still in the unlocked position.Leads number one and three should beelectrically open until the piston is retracted andlocked in what will be the landing gear downposition on the JetStar.

15

These suggestions on updating your main landinggear actuators are by no means complete, andthey are not intended to replace your authorizedsources of instructions. We assume that you willhave, for reference, blueprint JL1470 referred toearlier. We hope that the emphasis we haveplaced on various important and unique featureswill be helpful.



CUSTOMER SERVICE DIVISION LOCKHEED-GEORGIA COMPANY A OIY1$10.-. OF LOC!CHEEO .AtllCAAJl'f COl'.r-Q~"fl()N MAJlllE-TA~ G(()R(U""- :kll06'!

~

previous page table of contents next page · previous page table of contents next page. do be sure...

Documents