airbus

B r i t i s h A i r w a y s E n g i n e e r i n g T r a i n i n g

Your Course NotesThese notes have been prepared by BritishAirways Engineering Training to provide asource of reference during your period oftraining.

The information presented is as correct aspossible at the time of printing and is notsubject to amendment action.

They will be useful to you during yourtraining, but I must emphasise that theappropriate Approved Technical Publicationsmust always be used when you are actuallyworking on the aircraft.

I trust your stay with us will be informativeand enjoyable.

JOHN QUINLISKTraining and Quality Delivery Manager

PNEUMATICPneumatic Level 2 (2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Engine Bleed System Description (3) . . . . . . . . . . . . . . . . . . . . . . . . 16Pneumatic System Warnings (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20Pneumatic System Operation (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24APU Bleed Air SPLY/X-Bleed System D/O (3) . . . . . . . . . . . . . . . . 36BMC Interfaces (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38Pneumatic Leak Detection System D/O (3) . . . . . . . . . . . . . . . . . . . . 42

MAINTENANCE COURSE - T1 (CFM56-5B/ME) 36 - PNEUMATIC

TABLE OF CONTENTS May 11, 2006Page 1

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PNEUMATIC LEVEL 2 (2)

SYSTEM OVERVIEW

The Pneumatic system is used to supply High Pressure (HP) air for airconditioning, pressurization, engine start and anti-icing. HP air can besupplied from both engines, the APU or an external ground source.

ENGINE BLEEDThe engine bleed air is pressure and temperature regulated prior tosupplying the pneumatic system. Air is bled from two engine HighPressure Compressor (HPC) stages, the Intermediate Pressure (IP)stage and the HP stage.The High Pressure Bleed Valve (HPV) supplies air to the system whenthe engines are at low power. Once the IP bleed is sufficient, the HPVcloses.All the engine bleed air is supplied to the pneumatic system throughthe main engine BLEED valve (or Pressure Regulating Valve (PRV)),which acts as a shut off and overall system pressure regulating valve.Each Bleed Monitoring Computer (BMC) monitors system pressureand will shut down the engine bleed in case of excessive pressure. Inaddition, an Overpressure Valve (OPV) is installed downstream fromthe bleed valve to protect the system in case of overpressure.The temperature of the engine bleed air is regulated to a maximumvalue. The hot bleed air goes through an air-to-air heat exchangercalled the precooler. Fan discharge air modulated by the Fan Air Valve(FAV), blows across the pre-cooler to maintain the temperature withinlimits.

APU BLEED/EXTERNAL AIRThe left and right bleed systems are connected by a crossbleed duct.A crossbleed valve enables their interconnection or isolation.The APU can also be used for bleed air supply. This is usually doneon the ground for air conditioning and for engine start.

However, APU BLEED air could also be used in flight, dependingon altitude. The APU bleed supply is connected to the left side of thecrossbleed duct.On the ground, a HP ground power unit can be connected to the leftside pneumatic system. The right side may be supplied by openingthe crossbleed valve.


PNEUMATIC LEVEL 2 (2) May 10, 2006Page 2


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SYSTEM OVERVIEW - ENGINE BLEED & APU BLEED/EXTERNAL AIR




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SYSTEM OVERVIEW (continued)

LEAK DETECTIONLeak detection loops are installed along the hot air supply ducts ofthe pneumatic system and are connected to the BMCs. The leakdetection system is organized into three loops. Here are the loops andthe protected areas: - PYLON: the pre-cooler outlet area,- WING: wing leading edge and belly fairing,- APU: APU aft supply duct (left hand side of the fuselage) from APUfirewall to wheel well area.




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SYSTEM OVERVIEW - LEAK DETECTION




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MEL/DEACTIVATION

PRV AND HPV DEACTIVATIONIn case of failure, the pneumatic system HPV must be deactivatedCLOSED for dispatch per Minimum Equipment List.The deactivation procedure is the same for both valves.Procedure:- associated BLEED switch selected OFF,- APU BLEED switch selected OFF,- open the fan cowl and thrust reverser cowl,- deactivate the thrust reverser at the Hydraulic Control Unit (HCU),- on the PRV, move the manual override to the CLOSED position,- secure in CLOSED position with locking pin,- reactivate the thrust reverser,- close cowls.




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MEL/DEACTIVATION - PRV AND HPV DEACTIVATION




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MEL/DEACTIVATION (continued)

WING LEAK DETECTIONThe WING leak detection is a dual-loop system. To generate a WINGLEAK warning, both A and B loops have to detect the overheat. Fordispatch, WING leak detection must be operational (at least one loop)on each wing. If a single loop fails, the MAINTENANCE messageAIR BLEED will be displayed on the STATUS page associated witha Centralized Fault Display System (CFDS) message L(R) WINGLOOP (INOP). The aircraft may be dispatched per MinimumEquipment List with the MAINTENANCE message displayed.For troubleshooting it is important to understand that the WINGdetection elements monitor much more than just the wings alone. Theprotected areas are:- wing leading edge (wing anti-ice supply duct),- air conditioning compartment - belly fairing - (pack supply,crossbleed manifold, APU supply, ground air supply),- APU forward supply duct (from the APU check valve through thewheel well).




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MAINTENANCE TIPS

TROUBLESHOOTING NOTENormal operation of the pneumatic system does not require electricpower. The HPV, PRV, OPV and FAV are all controlled and operatedpneumatically. The BMC monitors the system operation and shutsdown the system in case of over temperature, over pressure or a Leak.During troubleshooting, it is very important to check the integrity ofall pneumatic sense-line connections. The BMC BITE does notconfirm the integrity of the system.




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MAINTENANCE TIPS - TROUBLESHOOTING NOTE




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MAINTENANCE TIPS (continued)

TEST SETA Test Set is available to assist in troubleshooting the pneumaticsystem. The test set enables calibrated pressure to be applied toindividual valves, components and isolated parts of the system tocheck for normal operation and sense line integrity. Several kinds ofvalves can be tested through the pneumatic system test set like:Pressure Regulating Valve, High Pressure Valve, Overpressure Valve,Fan Air Valve.




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MAINTENANCE TIPS - TEST SET




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MAINTENANCE TIPS (continued)

ENGINE START WITH GROUND AIRTo perform an engine start with ground air, the connection is locatedon the lower fuselage. The access door is on the belly fairing.During a ground air start, the crossbleed valve must be operatedmanually. For safety, it is recommended to use the ground air supplyto start the first engine. Then disconnect the ground air supply andperform a crossbleed start for the second engine.On the ECAM BLEED page, the GND indication DOES NOT indicateground air supply connected or available. This indication appearswhen the aircraft is on the ground to show that the ground air isdirectly supplied to the LEFT side of the system only. The left bleedsystem pressure indicator will indicate pressure when the ground airis supplied.




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MAINTENANCE TIPS - ENGINE START WITH GROUND AIR




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ENGINE BLEED SYSTEM DESCRIPTION (3)

GENERAL

The engine air bleed pressure is pneumatically regulated by the HighPressure (HP) Valve (VLV) when air is supplied by the HP stage, or bythe Pressure Regulating Valve (PRV) when the air is supplied by theIntermediate Pressure (IP) stage. The pressure regulation system ismonitored by two Bleed Monitoring Computers (BMCs).

HP VALVE

Switching between IP and HP is done pneumatically when the IP stagepressure is not sufficient (engine at low speed). The HP VLVpneumatically regulates the air supply between 8 and 36 psi. The HPVLV is forced to close when the PRV is closed via the PRV/HP VLVsense line. In flight, the Engine Electronic Controller (EEC) for IAEV2500-5A engines or the BMC for the A318/A319 fitted with CFM56engines maintains the HP VLV closed.When the solenoid is de-energized, the opening of the HP VLV is notinhibited. The solenoid will be energized by the BMC/EEC (dependingon the engine type) when:- the engine is above idle, the pressure PS3 is greater than 110 psi for thesingle aisle family IAE V2500 engines, or 80 psi for the CFM-56 engines.- the Wing Anti-Ice (WAI) is OFF,- the altitude is over 15,000 ft,- the pack configuration is normal.

IP CHECK VALVE

The IP check valve protects the IP stage from reverse flow when the HPVLV is open.

PRV/CONTROL SOLENOID

The PRV pneumatically regulates the bleed pressure around 44 psi. Athermal fuse causes the valve to close in case of engine fire at 450°C

(842°F). The PRV is pneumatically controlled by an externalservo-control, the bleed pressure regulated valve control solenoid (CTLSOL), located downstream from the precooler. The control solenoidoperates in two modes, pneumatic and electric, causing a partial orcomplete closure of the PRV.

NOTE: Note: for the A318, the control solenoid operates in two modes,pneumatic and electric, causing complete closure of the PRV.

The pneumatic mode is used for:- reverse flow protection - the PRV is closed when a delta pressurebetween the precooler outlet and the PRV inlet is detected,- temperature limitation downstream from the precooler, through thethermostat located in the control solenoid. When the temperature increasesand reaches 235°C (455°F), the PRV downstream pressure isprogressively reduced. When the temperature increases to more than 245°C, the downstream pressure is reduced to a maximum of 17.5 psi.

NOTE: Note: for the enhanced pneumatic system, the thermostat of thecontrol solenoid is no longer installed. The temperaturelimitation function is no longer available. When 235°C (455°F)is reached, the PRV no longer decreases the pressure to reducethe temperature downstream.

The electrical mode with PRV shut-off function through energization ofthe control solenoid is used when:- the ENGine BLEED P/B is selected "OFF",- the ENGine FIRE P/B is RELEASED OUT,The solenoid is automatically energized by the BMC in the followingcases:- over-temperature downstream of the precooler - the heat exchangeroutlet temperature sensor senses a temperature above 257°C (527°F),- overpressure downstream of the PRV when the pressure-regulatedtransducer senses a pressure greater than 57 psi,- leak detection in pylon/wing/fuselage ducts and surrounding areas,- APU bleed valve not closed,


ENGINE BLEED SYSTEM DESCRIPTION (3) May 10, 2006Page 16


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- corresponding starter valve not closed.

OPV

The Overpressure Valve (OPV), which is normally open, closespneumatically. The OPV starts to close at 75 psi. It is fully closed at 85psi and opens again at around 35 psi.

REGULATED PRESSURE

A transducer, connected to both BMCs, reads the regulated pressuredownstream from the PRV. This pressure is indicated on the ECAM.

NOTE: Note: for the enhanced pneumatic system, the cooling efficiencyis increased due to a new heat exchanger.

TRANSFERRED PRESSURE

A transducer, connected to the related BMC, reads the transferred pressuredownstream from the High Pressure Valve (HPV). This pressure is usedto monitor the PRV and the HPV.

FAV/CONTROL THERMOSTAT

The Fan Air Valve (FAV) pneumatically regulates the fan airflow to theprecooler for bleed air temperature regulation at 200°C (392°F). TheFAV is pneumatically controlled by an external servo-control: the FAVcontrol thermostat (CTL THERMST), located downstream from theprecooler.

PRECOOLER

The precooler is an air-to-air heat exchanger.

NOTE: for the A318, the thermal efficiency is increased.

HEAT EXCHANGER OUTLET TEMPERATURE SENSOR

The heat exchanger outlet temperature sensor, connected to both BMCs,reads the regulated temperature downstream from the precooler. Thistemperature is shown on the ECAM and used to monitor the system.

NOTE: Note: for the enhanced system, the high outlet temperaturethreshold is decreased. If the precooler exchanger outlettemperature reaches 240°C (464°F), the BMC generates a class2 maintenance message - "AIR BLEED" - on the ECAMSTATUS page. An associated maintenance message"Thermostat (THRMST), FAV or sense line" can be seen onthe MCDU.




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GENERAL ... HEAT EXCHANGER OUTLET TEMPERATURE SENSOR




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PNEUMATIC SYSTEM WARNINGS (3)

ENG 1 (2) BLEED ABNORM PR

If an ENG 1 (2) BLEED ABNORM PR occurs, the aural warning sounds,the MASTER CAUTion light comes on. The failure is shown amber onthe EWD associated to indications on the ECAM BLEED page. Theengine bleed valve is displayed amber on the ECAM. This warning istriggered when the engine-regulated pressure is below the detectionthreshold or below the minimum operating pressure of thepressure-regulating valve.

ENG 1 (2) BLEED LO TEMP

If an ENG 1 (2) BLEED LO TEMP occurs, the aural warning sounds,the MASTER CAUT light comes on. The failure is shown amber on theEWD associated to indications on the ECAM BLEED page. Warning isactivated when the temperature of one engine bleed drops below 150°C(302°F) in flight with wing anti-ice set to ON.

X BLEED FAULT

When the APU is running and the APU bleed is set to ON, if a X BLEEDFAULT occurs, the aural warning sounds, the MASTER CAUT lightcomes on. The failure is shown amber on the EWD associated toindications on the ECAM BLEED page. The engines and the APU arerunning. The APU bleed is set to ON. If, after setting APU bleed air toOFF, the X bleed valve position disagrees with the command logic, thiswarning is triggered. This warning also occurs, when the valve is stuckto close and the APU bleed P/B is set to ON. The warning always occurs,when there is a disagreement between the valve and the desired position.

ENG 1 (2) HP VALVE FAULT

The failure is shown amber on the EWD associated to indications on theECAM BLEED page. This warning is triggered by the transferred pressuretransducer, when the transferred pressure is lower than 23 psi during

more than 15 sec and the HP valve stays closed, when the engine is atidle.

BLEED MONITORING FAULT

If a BLEED MONITORING FAULT occurs, the failure is shown amberon the EWD; no pressure and temperature data is available on the ECAMBLEED page. This failure occurs when both Bleed Monitoring Computers(BMCs) are faulty.

L (R) WING LEAK DET FAULT

If a L (R) WING LEAK DETection FAULT occurs, the failure is shownamber on the EWD associated to indications on the ECAM BLEED page.This failure occurs when both detection loops are inoperative in the leftwing.

ENG 1 (2) BLEED FAULT

If an ENG 1 (2) BLEED FAULT occurs, the aural warning sounds, theMASTER CAUT light comes on, the ENGine bleed valve closes and theengine bleed fault light comes on. The failure is shown amber on theEWD associated to indications on the ECAM BLEED page. If bleed airpressure located downstream from the engine bleed valve, or temperaturelocated downstream from the pre-cooler is above the detection threshold,above 4 bar (57 psi) or 257°C (495°F), the bleed valve is automaticallyclosed.

NOTE: If the HP valve was open, the engine bleed valve closure causesit to close.

L (R) WING LEAK

If a L (R) WING LEAK occurs, the aural warning sounds, the MASTERCAUT light comes on, the engine bleed valve closes and the engine bleedfault light comes on. The failure is shown amber on the EWD associated


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to indications on the ECAM BLEED page. If leak loop temperature isabove the detection threshold of 124°C (255°F), this warning is triggered.

ENG 1 (2) BLEED LEAK

If an ENG 1 (2) BLEED LEAK occurs, the aural warning sounds, theMASTER CAUT light comes on, the engine bleed valve closesautomatically and the engine bleed fault light comes on. The failure isshown amber on the EWD associated to indications on the ECAM BLEEDpage. The pylon alarm temperature quantity is 204°C ± 12°C (399°F ±54°F).

ENG 1 (2) BLEED NOT CLSD

If an ENG 1 (2) BLEED NOT CLoSeD occurs, the aural warning sounds,the MASTER CAUT light comes on, the engine bleed fault light comeson if the engine bleed valve is not closed automatically. The failure isshown amber on the EWD associated to indications on the ECAM BLEEDpage. The engine 1 bleed valve is not automatically closed, when theAPU bleed valve is open. The warning is the same if the engine bleedvalve is not automatically closed during engine start.

BLEED 1 (2) OFF

If a BLEED 1 (2) OFF occurs, the aural warning sounds, the MASTERCAUT light comes on, the ENG BLEED OFF light comes on if oneengine bleed is switched off. The failure is shown amber on the EWDassociated to indications on the ECAM BLEED page.

APU BLEED FAULT

If an APU BLEED FAULT occurs, the aural warning sounds, theMASTER CAUT light comes on, the APU bleed fault message appearsif the APU is running and the APU bleed valve position disagrees withthe selected position. The failure is shown amber on the EWD associatedto indications on the ECAM BLEED page.

APU BLEED LEAK

If an APU BLEED LEAK occurs, the aural warning sounds, the MASTERCAUT light comes on, the APU bleed fault light comes on, the APUbleed and the cross bleed valves close. The failure is shown amber onthe EWD associated to indications on the ECAM BLEED page. If theleak loop temperature is above the detection threshold, this warning istriggered.

NOTE: If an engine was running, its associated engine bleed valve isautomatically controlled to open. The cross bleed valve maybe reopened by setting its selector to the OPEN position.




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PNEUMATIC SYSTEM OPERATION (3)

APU AIR BLEED SELECTION

When the APU runs and the APU BLEED P/BSW is released out, thesupply air goes up to the APU bleed valve which is closed. When theAPU BLEED P/BSW is selected in the ON position the APU bleed valveopens, the Pressure Regulator Valves (PRVs) are maintained electricallyclosed and the X BLEED valve is automatically opened, provided the XBLEED valve selector is in the AUTOmatic position.


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APU AIR BLEED SELECTION




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ENGINE AIR BLEED SELECTION

When one engine or both engines run and the APU runs, each PRVremains electrically closed by the related Bleed Monitoring Computer(BMC). When both engines run, the APU continues to supply air as longas the APU bleed valve remains open. When the APU BLEED valveP/BSW is released out, the APU bleed valve closes, the X BLEED valvecloses automatically and the PRVs open.




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HP/IP ENGINE STAGE PRIORITY

The APU is shut down and both engines are running.

THRUST LEVERS IN IDLE POSITIONWith both thrust levers in the idle position, the HP (High Pressure)Valves (VLVs) are open and supplying air.




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HP/IP ENGINE STAGE PRIORITY (continued)

THRUST LEVER IN TAKE-OFF POSITIONWhen the power of the engines is increased to the Takeoff (TO)position, the HP VLV is closed, and the bleed air is supplied by theIntermediate Pressure (IP) stage.

NOTE: Note: if you set again the thrust levers in the idle position,the HP VLV is open again.




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HP/IP ENGINE STAGE PRIORITY (continued)

ENGINES SHUT DOWNWhen the engines are shut down, the PRV, Fan Air Valve (FAV) andHP VLV are springloaded closed due to the lack of air pressure.




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GROUND AIR SUPPLY

The ground air supply is provided by a ground air cart connected to theHP ground connector. Only the LH bleed system is supplied. When theX BLEED valve selector is selected in the OPEN position, the groundair supply is available to feed the LH and RH bleed system.




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APU BLEED AIR SPLY/X-BLEED SYSTEM D/O (3)

APU BLEED

The pneumatic system can be supplied by the APU bleed air, through theAPU bleed valve, provided that the APU is running.The Bleed Load Valve for the APU GTCP 36-300A (GARRETT) andthe Load Control Valve of Honeywell APU 131-9A are electricallycontrolled by the ECB (solenoid) and pneumatically operated. In theabsence of air pressure or electrical power, the valves are spring-loadedclosed.

NOTE: These valves are of the ON/OFF typeThe APU Bleed Control Valve for the APIC APU is electrically controlledand fuel operated by a servo valve. The Electronic Control Box (ECB)monitors the fuel muscle pressure, which closes or opens the APU bleedvalve. In the absence of fuel pressure or electrical power, the valve shutsoff the bleed supply to the aircraft pneumatic system.

X-BLEED SYSTEM

The cross bleed (X-BLEED) valve permits the isolation or theinterconnection of the left and right bleed air systems. The OPEN manualcontrol is used for:- cross supply of the packs,- engine cross bleed start on ground only,- engine bleed air failure in icing conditions for Wing Anti-Ice (WAI)supply,- engine 2 start from ground cart supply.The X-BLEED valve is an electrically controlled shut-off valve. It isoperated by two electrical DC motors:- the primary motor is used for AUTOmatic mode, the position of thevalve is controlled by the Bleed Monitoring Computer (BMC) accordingto APU bleed configuration,

- the secondary motor is used to override the AUTO mode. The positionof the valve is then controlled by the X-BLEED selector for SHUT - offor OPEN, on the overhead panel.

HP GROUND CONNECTION

The pneumatic system may be supplied by a ground cart. The supplyduct is located to the left of the cross bleed valve. Only the LH bleedsystem is supplied. When the X-BLEED selector is in the OPEN position,the ground air supply will be available to supply the LH and RH systemtogether.


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APU BLEED ... HP GROUND CONNECTION


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BMC INTERFACES (3)

INPUTS

Each Bleed Monitoring Computer (BMC) has three types of inputs:- DIGITAL INPUTS via ARINC 429 buses, from the opposite BMC,corresponding Engine Interface Unit (EIU) and Centralized Fault DisplayInterface Unit (CFDIU),- ANALOG INPUTS from the bleed sensors,- DISCRETE INPUTS from valve position switches, BMC and overheadpanel. 28V DC power is supplied for energization of the bleed PressureRegulating Valve (PRV) control solenoid.


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INPUTS




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BMC INTERFACES (3)

OUTPUTS

Each BMC has two types of outputs:- DIGITAL OUTPUTS via ARINC 429 buses to the System DataAcquisition Concentrators (SDACs) for ECAM warnings and indications,the CFDIUs for maintenance purposes, and the opposite BMC for bleedmonitoring purposes,- DISCRETE OUTPUTS to the APU Electronic Control Box (ECB) forAPU availability, to the overhead panel for bleed faults, to the cross bleedvalve, control solenoid and Zone Controller (ZC).

NOTE: In case of BMC failure, the monitoring of main parameterssuch as High Pressure (HP) Valve (VLV), PRV, heat exchangeroutlet temperature sensor, and regulated pressure transducer,is kept, but the automatic control of the PRV is lost.




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OUTPUTS




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PNEUMATIC LEAK DETECTION SYSTEM D/O (3)

ROUTING

The leak detection system is used to detect leaks in the vicinity of thepacks, wings, pylons and APU hot air ducts. Each wing is monitored bya double loop. The pylon and APU hot air ducts are monitored by a singleloop. A continuous monitoring system detects ambient overheat in thevicinity of the hot air ducts.Protected areas with double loop for:- RH wing and pack 2,- LH wing, pack 1 and mid fuselage APU duct.Protected areas with single loop for:- LH and RH pylons,- AFT fuselage APU duct.

NOTE: Each loop consists of sensing elements connected in series.


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ROUTING




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WARNING LOGIC

Both Bleed Monitoring Computers (BMCs) receive signals from the leakdetection loops. They exchange data via an ARINC bus for the wingdouble loop detection.

NOTE: The wing loops A are connected to BMC 1 and wing loops Bto BMC 2. The crosstalk bus allows wing leak warnings to beactivated through an AND logic. The APU loop is connectedto BMC 1 only. The pylon loop is connected to the relatedBMC.




3T06

191

- U

13T

1M0

- U

M36

D40

0000

0001

WARNING LOGIC




3T06

191

- U

13T

1M0

- U

M36

D40

0000

0001


FAULT LOGIC

The ENG BLEED FAULT light comes on when a leak is detected by thewing loops A and B or by the pylon loop. The APU BLEED FAULTlight comes on when an APU duct leak is detected. If one BMC is failed,the adjacent BMC takes over monitoring of the bleed system and ensuresthe following ECAM warnings:- OVERPRESSure,- OVERTEMPerature,- WING LEAK.Nevertheless the associated FAULT light on the AIR CONDitioningpanel is lost, and the associated bleed valve does not close automatically.The ENG BLEED LEAK warning is lost for the associated engine aswell as the APU BLEED LEAK warning if BMC 1 is failed.




3T06

191

- U

13T

1M0

- U

M36

D40

0000

0001

FAULT LOGIC




3T06

191

- U

13T

1M0

- U

M36

D40

0000

0001


LEAK CONSEQUENCE

A detected leak will close associated valves, as shown on this table. Thesevalves are automatically controlled to close if they were open.

NOTE: APU and cross bleed (X-BLEED) valves do not close duringMain Engine Start (MES).




3T06

191

- U

13T

1M0

- U

M36

D40

0000

0001

LEAK CONSEQUENCE




3T06

191

- U

13T

1M0

- U

M36

D40

0000

0001

airbus

Documents

pneumatic pneumatic

pneumatic system hpv

pneumatic system operation

pneumatic system warnings

bleed air supply

hot bleed air

apu bleed supply

ip bleed