a330 36 pneumatic

A330-200/300 TECHNICAL TRAINING MANUAL

DIFFERENCE COURSE - A330 PW/RR to A330 GE CF6 -T1/T1+T2

PNEUMATIC

This document must be used for training purposes only

Under no circumstances should this document be used as a reference

It will not be updated.

All rights reservedNo part of this manual may be reproduced in any form,

by photostat, microfilm, retrieval system, or any other means,without the prior written permission of AIRBUS S.A.S.

AIRBUS Environmental RecommendationPlease consider your environmental responsability before printing this document.

PNEUMATIC36 Pneumatic System Presentation (GECF6) (1) . . . . . . . . . . . . . . . . . 2Pneumatic Line Maintenance Briefing (GECF6) (2) . . . . . . . . . . . . . 20Bleed Air Distribution & Supply D/O (GECF6) (3) . . . . . . . . . . . . . 40Engine Bleed Air Managmnt SYS Gen. D/O (GE) (3) . . . . . . . . . . . 48Engine Bleed Air Transfer System D/O (GECF6) (3) . . . . . . . . . . . . 52Engine Bleed Air Press. Reg. SYS D/O (GECF6) (3) . . . . . . . . . . . . 54

DIFFERENCE COURSE - A330 PW/RR to A330 GE CF6 - T1/T1+T2 36 - PNEUMATIC

TABLE OF CONTENTS Nov 21, 2008Page 1

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36 PNEUMATIC SYSTEM PRESENTATION (GECF6) (1)

GENERAL

The pneumatic system is used to supply air to various A/C systems. Thismodule describes:- the system sources and users,- the engine, APU and HP Ground Unit bleed air management system,- the leak detection system,- the control and indicating,- the maintenance and test facilities.When you work on A/C, you must obey all the safety procedures listedin the AMM.


36 PNEUMATIC SYSTEM PRESENTATION (GECF6) (1) Nov 20, 2008Page 2


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GENERAL




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SOURCES AND USERS

The pneumatic system may be supplied with High Pressure (HP) bleedair from 3 types of sources:- ground cart,- APU,- engines.The bleed air is distributed to the different users via a distribution andsupply ducting network. These users are:- the water system pressurization,- the hydraulic reservoir pressurization,- the wing anti-icing system,- the engines starting systems,- the packs bay ventilation system,- the air conditioning packs,- the thrust reverser system.The pneumatic system operates pneumatically and is monitored by twoBleed Monitoring Computers (BMCs) one, two.There is one BMC for each engine bleed system. Both BMCs exchangedata. If one BMC fails, the other BMC takes over most of its monitoringfunctions.

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 HP bleed is only used when the engines are at low power. Oncethe IP bleed is sufficient, the High Pressure Valve (HPV) closes.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 BMC monitors system pressure and will shut down the engine

bleed in case of excessive pressure. In addition, an overpressure valve(OPV) is installed downstream from the bleed valve to protect thesystem 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 precooler to maintain the temperature withinlimits.

APU BLEED/HP GROUND UNIT BLEEDA crossbleed duct connects the left and right bleed systems. Acrossbleed 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, APUBLEED air could also be used in flight, depending on altitude. TheAPU bleed supply is connected to the left side of the crossbleed 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.




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SOURCES AND USERS - ENGINE BLEED & APU BLEED/HP GROUND UNIT BLEED




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LEAK DETECTION

Leak detection loops are installed along the hot air supply ducts of thepneumatic system. The loops are made of multiple sensing elementsconnected in series. A dual loop detection system is installed in the wings,the mid fuselage above the air conditioning packs area and on the APUbleed duct. Two loops A and B are routed in parallel along the air ducts.An "AND" logic ensures the interconnection of the loops in the BMCsto prevent spurious warnings. In each engine pylon, a single detectionloop ensures the leak detection.The leak detection loops are connected to the BMCs. If a leak is detected,a signal is sent to the BMC one, or two, which automatically isolates theaffected area, triggers a warning signal to the ECAM system through theSystem Data Acquisition Concentrator (SDAC) and sends a fault messageto the Central Maintenance Computer (CMC).




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LEAK DETECTION




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CONTROL AND INDICATING

This section highlights the control panels and indications for thepneumatic system.

CONTROL PANELControls for the pneumatic system are part of the AIR COND panel,located on the overhead panel.




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CONTROL AND INDICATING - CONTROL PANEL




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CONTROL AND INDICATING (continued)

ECAM INDICATIONThe pneumatic system indications are displayed on the lower part ofthe ECAM BLEED page.




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CONTROL AND INDICATING - ECAM INDICATION




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COMPONENT LOCATION

The main components of the pneumatic system are located on the enginesand in the pylons.

ENGINE BLEED COMPONENTSThe IPC, the High Pressure Valve (HPV), the PRV, the FAV arelocated on the engine. The OPV and the precooler are located in thepylon.




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COMPONENT LOCATION - ENGINE BLEED COMPONENTS




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COMPONENT LOCATION (continued)

APU AND X BLEED COMPONENTSThe crossbleed valve is located in the forward section of the lowerfuselage belly fairing area. Get access to the HP ground connectorthrough a small access door located on the lower fuselage belly fairing.The APU bleed valve is located on the APU.




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COMPONENT LOCATION - APU AND X BLEED COMPONENTS




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MAINTENANCE/TEST FACILITIES

The CMCs let the maintenance crew read the failure data in the BMCsBITE via the MCDUs.




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MAINTENANCE/TEST FACILITIES




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SAFETY PRECAUTIONS

When you work on A/C, make sure that you obey all the AMM safetyprocedures. This will prevent injury to persons and/or damage to the A/C.Here is an overview of the main safety precautions relative to thepneumatic system.Make sure that the pneumatic system is depressurized before starting thework as pressurized air can cause unwanted pressurization of the A/C,and injury to personnel.Parts can be hot for 1 hour after engine shutdown. Do not touch themuntil they are sufficiently cool.




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SAFETY PRECAUTIONS




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PNEUMATIC LINE MAINTENANCE BRIEFING (GECF6) (2)

SYSTEM OVERVIEW

The pneumatic system is used to supply air to various A/C systems. Thismodule will review:- the system sources and users,- the engine APU and High Pressure (HP) ground unit bleed airmanagement system,- the leak detection system,- and the control and indicating.This module will also introduce some typical line maintenance activities.


PNEUMATIC LINE MAINTENANCE BRIEFING (GECF6) (2) Nov 20, 2008Page 20


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SYSTEM OVERVIEW




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SYSTEM OVERVIEW (continued)

SOURCES AND USERSThe pneumatic system is used to supply temperature and pressureregulated air to various A/C systems.The pneumatic system may be supplied with HP bleed air from 3 typesof sources:- ground cart,- APU,- engines.The bleed air is distributed to different users via a distribution andsupply ducting network. These users are:- the water system pressurization,- the hydraulic reservoir pressurization,- the wing anti-icing system,- the engines starting systems,- the air conditioning compartment ventilation system,- the air conditioning packs.The pneumatic system operates pneumatically and is monitored bytwo Bleed Monitoring Computers (BMCs) 1 and 2.There is one BMC for each engine bleed system. Both adjacent BMCsexchange data. If one adjacent BMC fails, the other BMC takes overmost of its monitoring functions.

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 HP bleed is only used when the engines are at low power. TheIntermediate Pressure Check Valve (IPC) and High Pressure Valve(HPV) control the bleed air supply. Once the IP bleed is sufficient,the HPV closes and the IPC opens.

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 BMC monitors system pressure and will shut down the enginebleed in case of excessive pressure. In addition, an OverPressure Valve(OPV) is installed downstream from the bleed valve to protect thesystem 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 precooler to maintain the temperature withinlimits. Each BMC monitors system temperature and will shut downthe engine bleed in case of excessive temperature.

APU BLEED/EXTERNAL AIR SUPPLYThe APU can also be used for bleed air supply. This is usually doneon the ground for air conditioning and for engine start. However, APUbleed air may also be used in flight, depending on altitude. The APUbleed supply is connected to the left side of the crossbleed duct. Thecrossbleed valve opens automatically to supply the right hand sidewhen the APU bleed is supplying the system.On the ground, an HP ground power unit can be connected to the lefthand side pneumatic system. The right hand side may be supplied byopening the crossbleed valve. A crossbleed duct connects the left andright bleed systems. A crossbleed valve enables their interconnectionor isolation.




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SYSTEM OVERVIEW - SOURCES AND USERS ... APU BLEED/EXTERNAL AIR SUPPLY




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SYSTEM OVERVIEW (continued)

LEAK DETECTIONLeak detection elements, connected in series, are installed along thehot air supply ducts of the pneumatic system and are monitored bythe BMCs. A dual loop detection system is installed in the wings, themid fuselage and in the air conditioning compartment to monitor thepacks and bleed ducts. The APU supply duct is also monitored by adual-loop system. The loops are made of multiple sensing elementsconnected in series. Two loops (A and B) are routed in parallel alongthe air ducts. The BMC uses "AND" logic to generate a leak warningand to prevent spurious warnings.In each engine pylon, a single detection loop is monitored for leaksby the respective BMC.




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SYSTEM OVERVIEW - LEAK DETECTION




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MEL/DEACTIVATION

The aircraft may be dispatched with one of the engine bleed valves PRVdeactivated, referring to the MEL. The conditions for dispatch requirethe valve to be locked in the closed position and the related engine bleedsystem is inoperative.Procedure to lock the valve closed:- open the LH fan cowl,- make the thrust reverser unserviceable and open the LH thrust reversercowl door,- on the PRV, remove the locking pin from its stowage,- on the manual override, make sure that the valve is in the CLOSEDposition and install the locking pin to secure the valve closed.The aircraft may also be dispatched with one of the engine HP valves(HPV - High Pressure Valve) deactivated, referring to the MEL. Theconditions for dispatch require the valve to be locked in the closedposition. In addition, the related engine bleed system should not be usedat low power setting.Procedure to lock the valve closed:- open the RH fan cowl,- make the thrust reverser unserviceable and open the RH thrust reversercowl door,- on the HPV, remove the locking pin from its stowage,- on the manual override, make sure that the valve is in the CLOSEDposition and install the locking pin to secure the valve closed.




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MEL/DEACTIVATION




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This Page Intentionally Left Blank




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MAINTENANCE TIPS

Troubleshooting Note:The condition of an overheat detection loop is checked by measurementof its Insulation Resistance (I/R), as detailed in the related TSM task36-22-00-810-xxx):- For the wings and APU loops, the I/R must be above 6 K - For engines pylon loops, the I/R must be above 25 K

NOTE: I/R measurement must be done using an Alternate Current (AC)loop controller (Example: 9240SI). The use of Direct Current(DC) loop controller will impact the electrical characteristicsof the sensing element.

A test set is available to help in troubleshooting of the pneumatic system.It is used to do an on-wing operational test of the HPV, PRV, FAV, OPVand pressure transducers.If the ENG BLEED LEAK warning is displayed on the ECAM, there isthe possibility of a high-pressure air leak on the engine pneumatic ducts.The leak may be found by using the (aluminum) foil-wrapping procedureto locate the source. This procedure is also used to check for leaks afterinstallation of a bleed valve or a duct.Procedure:- wrap the foil around the joint one time,- twist the seam of the foil wrap tight,- secure the foil wrap on either side of the joint with lockwire,- run the engine,- after shutdown, check for any evidence of leaks.

NOTE: The leak may also be found by using the alternative procedurewith the use of the dry developer.

The GND indication on the ECAM BLEED page sometimes causesconfusion. It does not indicate that external pneumatic supply is connectedor even that the access door is open. GND appears on the BLEED page

when the aircraft is on the ground to indicate that the external pneumaticsupply will be connected directly to the left hand side of the system. Theonly indication that external ground air is supplied is indication of systempressure on the left hand side. To make an engine start with ground air,the connection is located on the lower fuselage. The access door is onthe belly fairing.During a ground air start, the crossbleed valve must be manually operated.For safety, it is recommended to use the ground air supply to start thefirst engine. Then disconnect the ground air supply and make a crossbleedstart for subsequent starts.The installation of PTFE (Teflon) seals on the bleed air duct is done intwo steps. First the installation of the filler ring inside the bleed ductgroove and then the installation of the seal with its green face visiblefrom outside.

NOTE: No lubricant has to be applied prior and/or during installationof PTFE seal.




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BLEED AIR DISTRIBUTION & SUPPLY D/O (GECF6) (3)

GENERAL

The crossbleed valve connects or disconnects the LH and the RHpneumatic manifolds. High Pressure (HP) ground connectors can supplyair to the LH pneumatic manifold and through the crossbleed valve tothe RH pneumatic manifold when connected to a ground cart. The APUcan supply air to the LH and RH pneumatic manifolds on ground andduring climb up to 23000 feet (7010 meters) and during the descent from21000 feet (6400 meters). The engine bleed air systems are connected tothe corresponding pneumatic manifold.


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HP AIR GROUND SUPPLY

The ground air source supplies air through the two HP ground connectorsinstalled at the bottom left of the belly fairing. Each connector containsa non-return valve and a built-in nipple. A short duct connects the HPground connectors to the crossbleed manifold, to the left of the crossbleedvalve. Once connected and switched ON, ground cart delivered pressurecan be checked on the ECAM BLEED page. This pressure indication isgiven through the engine bleed system.

CAUTION: all A/C bleed systems must be switched off before thecrossbleed manifold is pressurized by the ground cart.




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HP AIR GROUND SUPPLY




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APU BLEED AIR SUPPLY

The main components of the APU bleed system are the APU bleed valveand the APU check valve.

APU BLEED AND CHECK VALVESThe APU bleed valve is an ON/OFF butterfly valve, spring loadedclosed, with a visual position indicator installed. It is electricallycontrolled by a solenoid and pneumatically operated. Its musclepressure is tapped upstream of the valve. A Fully Closed (FC)/NOTFC micro switch is installed on the valve for indicating and monitoringpurposes. The check valve protects the APU from reverse flow whenanother source supplies bleed air at a higher pressure.

APU BLEED VALVE CONTROLOnce the APU BLEED P/B is set to ON, a ground signal is sent toboth Bleed Monitoring Computers (BMCs). Then, the BMCs send anopening command to the Electronic Control Box (ECB) if thefollowing conditions are met:- the APU master switch is ON,- the APU BLEED P/B is ON,- no leak is detected on the APU bleed duct,- and no leak is detected on the LH pneumatic manifold.Note that these two leak conditions are not active during Main EngineStart (MES).Once the ECB receives the opening command, it energizes the bleedvalve solenoid only if:- the APU runs at more than 95% of speed,- no APU shutdown is carried out,- and the altitude is lower than 23000 feet (7010 meters)during climbor 21000 feet (6400meters) during descent.As a consequence, the APU bleed valve opens, the Pressure RegulatingValves (PRVs) of the two engines automatically close and the

crossbleed valve automatically opens when the APU supplies bleedair to the users. APU bleed valve position and bleed pressure areindicated on the ECAM BLEED page (the pressure value is given bythe engine bleed system).




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APU BLEED AIR SUPPLY - APU BLEED AND CHECK VALVES & APU BLEED VALVE CONTROL




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CROSSBLEED SYSTEM

The crossbleed valve is an electrically controlled butterfly shut-off valve.Two electrical motors, which work independently, are used for manualor automatic operation. A Fully Open (FO) or Fully Close (FC) positionof the valve is sent to the two BMCs by 2 micro switches. Either automaticor manual control can be selected using the crossbleed valve selector ofthe AIR panel.

AUTOMATIC CONTROLWhen the crossbleed valve selector is in the AUTO position, thecrossbleed valve control is carried out by the BMCs, through theprimary valve motor. As soon as:- the APU BLEED P/B is ON,- the APU bleed valve is not FC,- and there is no leak detected,the BMCs send a ground signal to the crossbleed valve auto-controlrelay.As a consequence, the crossbleed valve auto-control relay supplieselectrical power to the crossbleed valve primary motor and thecrossbleed valve opens. The FO position feedback from themicroswitch is indicated on the ECAM BLEED page through theBMCs. When the APU BLEED is deselected, the APU bleed valvecloses and, in turn, the crossbleed valve closes.The FC feedback from the second microswitch is displayed on theBLEED page.

MANUAL CONTROLThe manual opening control can be used in the subsequent cases:- cross supply by a ground cart,- crossbleed engine start,- or when an engine bleed system fails.

As soon as a manual control is selected, the crossbleed valve primarymotor power supply is cut out. When the crossbleed valve selectorswitch is set to OPEN, it directly supplies the secondary crossbleedvalve motor, which opens the valve. When the crossbleed valveselector switch is set to CLOSE, the secondary motor closes thecrossbleed valve. As in the automatic mode, the valve position is givenby the 2 microswitches and shown on the ECAM BLEED page.

INCORRECT OPERATIONIf a disagreement between the valve position and command occurs,the BMCs trigger an ECAM message and the BLEED page comes upautomatically.




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CROSSBLEED SYSTEM - AUTOMATIC CONTROL ... INCORRECT OPERATION




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ENGINE BLEED AIR MANAGMNT SYS GEN. D/O (GE) (3)

GENERAL

The main air bleed sources are the engines. Air can be bled from twodifferent stages. It is generally bled from an Intermediate Pressure (IP)stage of the engine compressor (stage 8) to minimize fuel penalty. Whenpressure from the IP bleed port is insufficient to supply the network, airis automatically bled from the High Pressure (HP) stage of the compressor(stage 14).Each engine bleed air system includes the following sub-system:- pneumatic transfer system. It selects one of the two compressor stagesof the engine HP compressor in agreement with the supplied pressure,- pressure limitation system to regulate the bleed air pressure in order toprevent overpressure,- temperature limitation system to regulate the bleed air temperature inorder to prevent over temperature.


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ENGINE BLEED AIR MANAGMNT SYS GEN. D/O (GE) (3)

BLEED AIR TRANSFER

The transfer from one bleed port to another is carried out using a HPbleed Valve (HPV) at the HP stage. The transfer depends on the availablepressure and engine speeds. In the normal engine bleed air configuration,the air is bled from the IP port at high engine speed. At low engine speed,especially during A/C descent with engines at idle, the IP port pressureis insufficient and the air is automatically bled from the HP port.Transfer to the IP stage can be forced by closing the HPV via a solenoidincorporated in the HPV. This transfer is commanded by the BleedMonitoring Computers (BMCs). The HPV can also be closed by actionon the engine BLEED P/BsA check valve located on the IP bleed port avoids reverse flow when airis bled from the HP stage.

PRESSURE LIMITATION

Air is then sent through the engine bleed air pressure regulation systemfirst composed of a Pressure Regulating Valve (PRV) associated to athermostat solenoid. The valve acts as a shut-off and PRV. The PRV isfully and pneumatically operated and controlled by the thermostatsolenoid. The shut-off function of the PRV through the thermostatsolenoid is controlled by the corresponding BMC or by using the ENGBLEED P/Bs located on the AIR panel or the engine FIRE P/B.A fully pneumatic Overpressure Valve (OPV) protects the system againstoverpressure.

TEMPERATURE LIMITATION

The temperature regulation of the bleed air system is carried out by a FanAir Valve (FAV), which modulates fan airflow through an air-to-air heatexchanger. The FAV is controlled by the BMC through the ControlThermostat (ThC). The temperature regulation gives two temperaturesettings: 200°C for nominal conditions (solenoid not energized) and

150°C on demand from the air conditioning system if the wing anti-icesystem is not operative (solenoid energized).Finally, bleed air is ducted to the bleed air distribution and supplynetwork.

MONITORING

The position of the valves, bleed air temperature and pressure are indicatedon the ECAM bleed page.




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BLEED AIR TRANSFER ... MONITORING




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ENGINE BLEED AIR TRANSFER SYSTEM D/O (GECF6) (3)

DESCRIPTION

The selection of the High Pressure (HP) compressor stage source on eachengine is carried out through a HP bleed Valve (HPV) and an IntermediatePressure (IP) check valve.

HP VALVEThe HPV is pneumatically operated for pressure limitation and safety.It is electrically controlled to close by a solenoid. The HPV is aspring-loaded closed shut-off valve. The minimum operating pressureof the valve is 10 psi. It pneumatically regulates the pressure around36 psi.It is equipped with a solenoid for valve operation control, and a FullyClosed (FC)/NOT FC microswitch for monitoring and indicating.For maintenance purposes, the HPV is equipped with a ground testport, a mechanical position indicator and a special screw with a manualoverride for locking in the closed position.

IP CHECK VALVEThe IP check valve is a non-return valve which closes automaticallyto prevent HP14 air from re-circulating toward the HP8 stage whenthe HPV is open.

BLEED TRANSFERRED PRESSURE TRANSDUCERThe bleed transferred pressure transducer is located in the enginepylon. Its pressure sense line tapping is taken downstream of the HPV.

NORMAL OPERATION

The HP8/HP14 bleed transfer control is pneumatically achieved. Whenthe HP8 stage pressure exceeds the HPV target value of an average of36 psi, the HPV closes and air bleed is supplied by the HP8 stage. TheHPV is electrically controlled close by solenoid energization either

automatically by the Bleed Monitoring Computer (BMC) or by ENGBLEED "OFF" pushbutton action.The HPV bleed valve position is shown on the SD BLEED page.

ABNORMAL HIGH PRESSURE BLEED VALVE CLOSURE

An abnormal BMC closure function is used for system protection purposesor during specific operations by solenoid energization.This HPV closing command is sent by the BMC any time the PressureRegulating Valve (PRV) is commanded closed and when an untimelyHP8/HP14 transfer is inhibited.The HP8/HP14 transfer is inhibited when the HP pressure is higher than85 psi and the Wing Anti Ice (WAI) is not selected and the altitude ishigher than 26000 feet (7925 meters), or when the compressor dischargetemperature is higher than 400 degrees Celsius and the HP14 pressurehigher than 75 psi.If the HP8/HP14 transfer fails, the HPV pneumatically closes when theupstream pressure is higher than 105 psi.

VALVE POSITION DISAGREEMENT

When the HPV is controlled open and is detected in the closed position,the BMC triggers an ECAM message and the BLEED page comes upautomatically.

MONITORING

The bleed transferred pressure transducer is used for system monitoringand fault isolation regarding the PRV and HPV. An associated faultmessage is sent to the Central Maintenance System (CMS) formaintenance purposes.


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DESCRIPTION ... MONITORING


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ENGINE BLEED AIR PRESS. REG. SYS D/O (GECF6) (3)

SYSTEM DESCRIPTION

The pressure regulating system is composed of several components:- the Pressure Regulating Valve (PRV),- the PRV control solenoid,- the Over Pressure Valve (OPV),- the bleed regulated pressure transducer.

PRESSURE REGULATING VALVEThe PRV is a fireproof, pneumatically operated, electrically controlled,pressure regulating and Shut-Off Valve (SOV). The PRV ispneumatically operated and electrically controlled by a PRV controlsolenoid.The "Fully Closed (FC)/NOT FC" position is sensed by a microswitchused for monitoring and indicating.The valve has a ground test port, a mechanical position indicator anda de-activation maintenance device.

PRV CONTROL SOLENOIDThe control solenoid fulfills the control of the PRV.The control solenoid pneumatically controls the pressure regulationdepending on the air temperature at the precooler outlet when thetemperature is higher than 235 degrees Celsius.The PRV shuts upon energization of the control solenoid.The solenoid is directly energized in case of:- ENG BLEED OFF P/B action,- ENG FIRE P/B action.It is also energized via the Bleed Monitoring Computer (BMC) incase of:- malfunction,- APU bleed supply,- engine start,- engine P/B action (for redundancy)

OVERPRESSURE VALVEThe OPV is a pneumatically actuated valve, spring-loaded open.Muscle pressure for valve actuation is tapped from an integral pressureport located upstream of the valve. The OPV gives protection to thedownstream pneumatic system if the PRV does not operate correctly.The valve closes depending on upstream pressure.

BLEED REGULATED PRESSURE TRANSDUCERThe PRV pressure transducer is linked by a pressure sense line to apressure tapping downstream of the PRV. The transducer is electricallyconnected to the BMC 1 and BMC 2.

PRESSURE REGULATION

The PRV is normally spring loaded closed in the absence of upstreampressure. A minimum upstream pressure of 8 psi is necessary to open thevalve.The PRV control solenoid controls the PRV closure when the valvesolenoid is energized by the BMC or by action on the ENG BLEED P/Bor ENG FIRE P/B.The PRV regulates pneumatically the downstream static pressure to:- 52 psi maximum,- 44 psi minimum.The PRV control solenoid pneumatically reduces the PRV regulatedpressure when the temperature downstream of the precooler exchangerexceeds 235 degrees Celsius. As soon as the valve regulates, valve openposition from the microswitch and actual regulated pressure can bechecked on the SD BLEED page.

BLEED SYSTEM ISOLATION FUNCTION

Each engine bleed system can be isolated from the pneumatic manifoldin abnormal or specific conditions by closing the PRV.


ENGINE BLEED AIR PRESS. REG. SYS D/O (GECF6) (3) Nov 20, 2008Page 54


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MANUAL ISOLATIONAn engine bleed system can be isolated manually from the manifoldby releasing the corresponding BLEED P/B on the AIR panel, andtherefore energizing the PRV solenoid, resulting in the PRV closure.The "FC/NOT FC" microswitch indicates the position of the valve tothe BMC, which is displayed on the ECAM BLEED page.

FIRE ISOLATIONIf an engine fire occurs, the bleed system of the affected engine isisolated by releasing the corresponding FIRE P/B on the overheadpanel, energizing the PRV solenoid. The ECAM BLEED page showsthe position of the PRVs.

AUTOMATIC ISOLATIONThe BMC can isolate automatically engine bleed air supply byenergizing the PRV control solenoid:- if a pylon or wing leak is detected,- if an overpressure occurs,- if an over temperature occurs,- during engine start,- during APU bleed supply.

OVERPRESSURE PROTECTION

If the bleed regulated pressure rises above 60 psi, the BMC detects anoverpressure condition and closes the PRV. A warning message isdisplayed on the EWD and the BLEED page comes up automatically onthe SD showing the High Pressure Valve (HPV) and the PRV closed inamber.In addition to the overpressure electrical monitoring done by the BMC,the OPV gives a fully pneumatic back up protection in case of PRVregulation failure. The OPV is designed to start to close automaticallywhen the upstream pressure increases above 75 psig and is fully closedat 85 psig (+0/-10 psig). The valve remains closed as long as the upstreampressure is higher than 52 psig (+3/-3 psig).

MONITORING

The bleed regulated pressure transducer is used for system monitoringand fault isolation regarding the PRV and OPV. An associated faultmessage is sent to the Central Maintenance System (CMS) formaintenance purposes.




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a330 36 pneumatic

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