ATA 49 APU.pdf

LufthansaTechnical Training

A3342/3 Auxiliary Power Unit



4900 GENERAL4910 POWER PLANT4912 APU MOUNTS4920 ENGINE4980 EXHAUST4917 POWER PLANT DRAIN SYSTEM4916 AIR INTAKE SYSTEM4990 OIL4991 OIL STORAGE AND DISTRIBUTION4993 OIL INDICATING4994 LOP AND HOT WARNING4996 APU OIL HEATING4930 ENGINE FUEL AND CONTROL4934 APU FUEL LP WARNING4950 AIR4951 BLEED AND SURGE AIR4952 ACCESSORY COOLING


4970 INDICATING4971 POWER INDICATING4972 TEMPERATURE INDICATING4973 ANALYZERS4940 IGNITION AND STARTING4960 ENGINE CONTROLS4961 CONTROL AND MONITORING

AUXILIARY POWER UNITGENERAL

A334-200/300GTCP 331350C

4900

ATA 49 AUXILIARY POWER UNIT


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4900 GENERAL4910 POWER PLANT4912 APU MOUNTS4920 ENGINE4980 EXHAUST4917 POWER PLANT DRAIN SYSTEM4916 AIR INTAKE SYSTEM4990 OIL4991 OIL STORAGE AND DISTRIBUTION4993 OIL INDICATING4994 LOP AND HOT WARNING4996 APU OIL HEATING4930 ENGINE FUEL AND CONTROL4934 APU FUEL LP WARNING4950 AIR4951 BLEED AND SURGE AIR


A334-200/300GTCP 331350C

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FRA US/E-1 WiK Feb 01, 2008

4900 GENERALAPU INTRODUCTIONGeneralThe APU (Auxiliary Power Unit) designation is Garrett GTCP 331350C.GTCP is an abbreviation for GasTurbine Compressor PowerUnit.

PurposeThe APU is an independent aircraft system for the alternative power supply ofthe electric and pneumatic system. It supplies the A/C (Air/Craft) Electrical System It supplies the A/C Pneumatic System

The primary users are the: ECS (Environmental Control System) for the airconditioning MES (Main Engine Start) System WAI (Wing Anti Ice) System

Operation on GroundOn ground, the APU permits the aircraft to operate independently from anexternal supply of pneumatic and electrical power during the ground serviceand maintenance.

Operation in FlightDuring the flight the main engines are the primary power supply for theelectrical system and the pneumatic system. The APU serves as a backuppower source in case of aircraft system malfunction.

Control and MonitoringAn ECB (Electronic Control Box) monitors the APU operation and gives full selfprotection. It is a FullAuthority Electronic Control.

Operation Data

Restart in Flight up to 41,000 ftEnergizing of Electrical Power up to 41,000 ftEnergizing of Pneumatic Power up to 23,000 ftConstant Speed 100% (N=41,730 rpm)Bleed Load 324 lb/min. (Sea Level, 37.8 C)Shaft Load 166 shp (Sea Level, 37.8 C)Max. EGT (Exhaust Gas Temperature 660 C on SpeedAir Pressure 35 psi Normal / 50 psi MaximumGenerator Output 115 Volts / 400 HzWeight 250 kg


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SUMMARY

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A334-200/300GTCP 331350C

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WING ANTI ICE

ENGINE START

AUXILIARYPOWERUNIT

APU LOADBLEED VALVE

X-BLEEDVALVE

APU CHECK VALVE


Page 3Figure 1 APU ECS-Supply Schematic


A334-200/300GTCP 331350C

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APU Operating EnvelopeThe starting and operating envelope limiting parameters are governed by theambient temperature and pressure altitude.The APU has the capability of providing pneumatic and shaft power to satisfyaircraft demands. Combination loading (electrical and pneumatic power) isavailable up to 23,000 ft. Electrical power which has priority over pneumaticsupply is available up to 41,000 ft.APU start operation may be accomplished up to 41,000 ft but starting merelywith APU battery is limited to 25,000 ft. On aircraft equipped with aTRU (Transformer Rectifier Unit) starts may be attempted up to 41,000 ft.


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A334-200/300GTCP 331350C

4900


APU BATTERY START LIMIT

APU RESTART AND OPERATION LIMIT

NORMAL AC POWER SUPPLY

60 40 20 0 20 40

74 54 30 2 1 . 5 17 22 55

AMBIENT AIR TEMPERATURE DEG.C

SHAFT PO

WER O

NLYBLEED

AIR AN

D SH

AFT POW

ER

0

10

40

1

14,616,6

38

41

PRESSURE ALTITUDE(1000 FT)

ISA = INTERNATIONAL STANDART ATMOSPHERE

22.5

25

GROUND STARTINGAND OPERATION LIMIT


Page 5Figure 2 APU Operating Envelope


A334-200/300GTCP 331350C

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APU CONTROLS

GeneralNormal control of the APU is carried out from the APU Control Panel 215VUlocated in the cockpit.The APU has an emergency shutdowncircuit which will stop the APUautomatically on ground if the APU fire and overheat detection system finds anoverheat in the APU compartment.During the flight you must push the APU SQUIB DISCH P/BSW on the FirePanel 231VU to operate the fire extinguishing system.However, a manual initiated emergency shutdown may performed on groundfrom outside of the aircraft at the following loations: External Power Control Panel 925VU Refuel/Defuel Panel 990VU


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A334-200/300GTCP 331350C

4900


APU FIRE PANEL

REFUEL/DEFUEL PANEL

SQUIB

DISCH

APU

TEST AGENT

CALLCOCKPIT N L G

LIGHTHORNRESET

LIGHTTEST

COCKPITCALL

AVNCSVENT ADIRU

APUFIRE

APU EMERG.

SHUTDOWN APUSHUT OFF

SVCE INT

START

MASTER SW

APU231VU

990VU

EXTERNAL POWER CONTROL PANEL

925VU

FAULT

ON/R

AVAIL

ON


Page 7Figure 3 APU Controls

AUXILIARY POWER UNITPOWER PLANT

A334-200/300GTCP 331350C

4910


4910 POWER PLANTAPU PRESENTATIONGeneralThe Auxiliary Power Unit [5100KB] is installed in the APU compartment in theaircraft tailcone. Access to the APU compartment is gained through the twoaccess doors 315AL and 316AR.The APU compartment has a forward firewall at FR95 and a rear firewall atFR101. An APU fire and overheat detection system and an APUfireextinguishing system protect the APU and the APU compartment in caseof a fire. The fire extinguisher bottle is installed on the front face of the forwardfirewall of the APU compartment (FR95).Also installed in the tailcone are the air intake system, the APU mountingsystem, the exhaust system and the power plant drainsystem.A drainmast is installed in the left access door 315AL. A louvered overpressurereleasedoor is installed in the structure on the top left side of the APUcompartment.


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A334-200/300GTCP 331350C

4910


FR95

FR101

APU DRAIN LINES

ACCESS DOOR315 AL

ACCESS DOOR316 AR

APU ACCESS DOORS

COMPARTMENTDRAIN MAST

AIR INTAKE


Page 9Figure 4 APU Installation and Access


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Identification PlateThe Identification Plate indicates the APU modification status after the lastshop maintenance. It contains the P/N (Part/Number), the Model- and theSeries number, the Change Number and some performance data of the APU. Itis located on the left side at the air plenum chamber.NOTE: Within the AMM (Aircraft Maintenance Manual) there are some

tasks, which are in relation to different APU modification status.The different procedures within a task are identified by the P/N,the Series Number and Change Number.


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A334-200/300GTCP 331350C

4910


PN 38004544DSGN ACT 99193MODEL GTCP331350[C]

SERNO R248 SERIES 47

MAX DRY WEIGHT 542.3 IBSMFR C0548TS C77A CAT I

INSP DATEFUEL(SEE MODEL SPEC)MAX 41,730 RPM RATEDSPEED44,651RPM ALLOWED

ENGINE,GAS TURBINE

GARRETT GMBH

SPECIAL MARKINGS

JARSERVICE CAT ESSENTIALLUBE (SEE MODEL SPEC)SL RATED 166SHP. 324LBS/MINOUTPUT 50.3PSIA AT 100 F DAY

MOD RECORD /63

RAUNHEIM, GRMANY

MAX 1196 F RATED 1215 F ALLOWEDMAX 647 C RATED 657 C ALLOWED


Page 11Figure 5 Identification Plate

AUXILIARY POWER UNITAPU MOUNTS

A334-200/300GTCP 331350C

4912


4912 APU MOUNTSSYSTEM PRESENTATIONThe APU has a threepoint Mounting System. Seven Rod Assemblies makethe connection between the three APU Mount Brackets and the top structure ofthe APU compartment. Three Vibration Isolators are installed between the RodAssemblies and the APU Mount Brackets. They prevent the twowaytransmission of vibrations and shocks between the APU and the structure in alldirections.The mounting system of the APU has the subsequent primary components: Structure Brackets (7ea.) Rod Assemblies (7 ea.) APU Mounting Brackets (3 ea.) Vibration Isolators (3 ea.)


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AUXILIARY POWER UNITAPU MOUNTS

A334-200/300GTCP 331350C

4912


AFT MOUNT

VIBRATION ISOLATOR

FWD LEFTMOUNT

FWD RIGHTMOUNT

ROD ASSEMBLY

MOUNT BRACKET


Page 13Figure 6 APU Mounts

AUXILIARY POWER UNITENGINE

A334-200/300GTCP 331350C

4920


4920 ENGINEGENERAL LAYOUTEngine ModulesThe engine is the primary component of the APU, it consists of three mainmodules: Power Section Load Compressor Accessory Drive Gearbox

The LRUs (Line Replaceable Units) of the APU are installed on the engine. Youcan remove or install them easily.


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A334-200/300GTCP 331350C

4920


ACCESSORYDRIVE GEARBOX

LOADCOMPRESSOR

POWERSECTION

ENGINE


Page 15Figure 7 Engine Modules


A334-200/300GTCP 331350C

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DESCRIPTIONCONSTRUCTIONThe APU is constructed as a modular design and consists of the followingthree Major Modules: Power Section which is subdivided into

Compressor Section and Turbine Section

Load Compressor Accessory Gear-Box (AGB)

POWER SECTIONCompressorThe Compressor is a submodule which can be removed at shop maintenancelevel and is of a two stage centrifugal compressor design. The maincomponents of the compressor are the: 1st Stage Impeller and Diffuser 2nd stage Impeller and Diffuser

Combustion ChamberThe combustion chamber is of a reverse flow annular design and fits inside theturbine plenum. The main parts of the combustion chamber are the: Combustion Chamber Liner Outer Combustion Chamber Case

The following components are installed on the combustion chamber: Igniter Plugs Fuel Nozzles Combustion Chamber Drain Valve

TurbineThe turbine is of a three stage axial design and can be removed at shopmaintenance level. It drives the compressor, the load compressor and thegeartrain of the accessory gearbox. The turbine first stage vanes and bladesare air cooled by compressor discharged air.

LOAD COMPRESSORThe load compressor is of a single centrifugal stage design.The main components of the load compressor are the: Inlet Guide Vane Assembly Impeller Collector Scroll Acoustic Material

Inlet Guide VanesThe IGV (Inlet Guide Vane) Assembly controls the airflow through the loadcompressor. The 24 Inlet Guide Vanes are moved simultaneously by ageartrain operated by an actuator.The Inlet Guide Vane actuator is operated by high pressure fuel supplied fromthe Fuel Control Unit.The Inlet Guide Vane opening angle depends on the bleed air demand for the:

MES (Main Engine Start) System and, ECS (Environmental Control System)

ACCESSORY GEARBOXThe AGB (Accessory Gear-Box) is directly connected to the Load CompressorModule which transmits the shaft power from the power section.The gearbox transmits the shaft power to the APU accessories and to the APUgenerator which are installed on the gearbox pads.The gearbox is also the oil reservoir for the APU oil system and providesattachment for the two forward APU Mounting Brackets. The majorcomponents mounted on the AGB are the: Electrical Generator Starter and Starter Clutch Assembly Compartment Cooling Fan Oil Pump Module which drives the Fuel Control Unit Gravity Oil Fill Port and Oil Level Sight Glass


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A334-200/300GTCP 331350C

4920


LOAD COMPRESSORIMPELLER

SCROLL COMPRESSORAIR COLLECTOR

INLET GUIDEVANES

1st STAGEIMPELLER

2nd STAGEIMPELLER

1st STAGETURBINE

2st STAGETURBINE

3rd STAGETURBINE

ANNULARCOMBUSTOR

GEARBOX

LOAD COMPRESSORMODULE

COMPRESSOR SECTION TURBINE SECTION

POWER SECTION


Page 17Figure 8 GTCP 331350 Engine X-Section


A334-200/300GTCP 331350C

4920

FRA US/E-1 WiK Feb 01, 2008 LufthansaTechnical Training

Page 18Figure 9 GTCP 331350 Engine Cutaway


A334-200/300GTCP 331350C

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COOLING FANATTACHMENTFLANGE

OIL PUMP/FUELCONTROL PAD

A

STARTERMOTOR PAD

GENERATORATTACHMENTFLANGE

VIEW-A


Page 19Figure 10 AGB Mounting Pads

AUXILIARY POWER UNITEXHAUST

A334-200/300GTCP 331350C

4980


4980 EXHAUSTDESCRIPTIONPurposeThe exhaust system releases the APU exhaust gas to the ambient air. Theexhaust gas contains the combustion gases and the load compressorsurgeair. The exhaust system also decreases the exhaust noise level, most ofthe noise comes from the outlet of the APU exhaust diffuser (the flange of theturbine heat shield).InstallationThe system is installed in the exhaust muffler compartment together with therear access fairing.The exhaust muffler goes through the rear firewall of the APU compartment. Ithas a thermal insulation to protect the structure of the exhaustmufflercompartment and the rear access fairing.The exhaust coupling makes a flexible connection to the turbine heat shieldand the exhaust muffler.

ConstructionA firewall seal seals the space between the exhaust and the rear firewall.

AccessTo get access to the exhaust system, you can open the rear access fairing317AL and the APU access doors 315AL and 316AR.


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AUXILIARY POWER UNITEXHAUST

A334-200/300GTCP 331350C

4980


EXHAUSTMUFFLER INSULATION

FIRE WALLSEAL

EXHAUSTCOUPLING

REAR PARTOF THETURBINEHEAT SHIELD


Page 21Figure 11 Engine Exhaust

AUXILIARY POWER UNITPOWER PLANT DRAIN SYSTEM

A334-200/300GTCP 331350C

4917


4917 POWER PLANT DRAIN SYSTEMDRAIN SYSTEM DESCRIPTION

GeneralThe APU drainsystem removes excess fluids from the APU and the APUExhaust Muffler to the external air. Thus it prevents that excess fluids cancollect on or in the power plant and cause a fire hazard. A Drain Mast isinstalled in the left access door of the APU compartment. Any excess fluidswhich could occur in the APU compartment, flow out of the drainmast to theatmosphere.The APU drain system is divided in the following two subsystems: Engine Drain System Accessory Drain System

Engine Drain SystemFollowing components are connected to the APU Engine Drain System: Combustion Chamber APU Exhaust Cone Exhaust Muffler

Accessory DrainFollowing components are connected to the APU Accessory Drain System: Inlet Guide Vane Actuator Surge Control Valve Actuator Fuel Control Unit/Oil Pump Module


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A334-200/300GTCP 331350C

4917


INLETGUIDEVANEACTUATOR

FUEL CONTR.UNIT/OILPUMPMODULE

DRAIN PORTAIRCHECK VALVE

COMBUSTIONCHAMBER

APU PLUMBING AIRCRAFTDRAIN LINES

ENGINEACCESSORIES

FR101REARFIREWALL

FR102

ENGINE DRAIN LINE

ACCESSORY DRAIN LINE

FUSELAGE/TAILCONE

DRAIN MASTON APUACCESS DOOR315AL

FR95

FWDFIREWALL

SURGECONTROLVALVEACTUATOR

COMBUSTIONCHAMBERDRAIN VALVE

APUEXHAUSTCONE

EXHAUSTMUFFLER


Page 23Figure 12 APU Drain System


A334-200/300GTCP 331350C

4917


Combustion Chamber Drain ValveThe Combustion Chamber Drain Valve is a control valve which is of the ballvalve type.When the APU does not operate, the valve is spring loaded open(Air Pressure 10 psi).


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A334-200/300GTCP 331350C

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DRAINS

TUBES

1 / 4


A334-200/300GTCP 331350C

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FROM THE APU- SCV ACTUATOR- IGV ACTUATOR- FUEL CONTROL UNIT- OIL PUMP MODULE- CAVITY DRAIN

EXHAUST CONEDRAIN PORT

ENGINEDRAIN LINE

ACCESSORYDRAIN LINE

EXHAUST MUFFLERDRAIN LINE


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DRAINS

TUBES

2 / 4


A334-200/300GTCP 331350C

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ENGINEDRAIN LINE

ACCESSORYDRAIN LINE


SECTION C-C C

CNORMALLYOPEN

AIR PRESSURECLOSED

COMBUSTION CHAMBER DRAIN VALVE


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DRAINS

TUBES

3 / 4


A334-200/300GTCP 331350C

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ENGINEDRAIN LINE

ACCESSORYDRAIN LINE


SECTION C-C C

CNORMALLYOPEN

AIR PRESSURECLOSED

COMBUSTION CHAMBER DRAIN VALVE

ATTENTION: APU Leak Rates are describedin the AMM 490000710801

316AR

315AL

COMPARTMENT DRAIN MAST


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DRAINS

TUBES

Figure 13 APU Drain Lines

4 / 4

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AUXILIARY POWER UNITAIR INTAKE SYSTEM

A334-200/300GTCP 331350C

4916


4916 AIR INTAKE SYSTEMAIR INTAKE SYSTEM DESCRIPTIONGeneralThe Air Intake System supplies ambient air to the inlet plenum chamber of theAPU. The location of the air intake prevents ingestion of the APU exhaustgases through the APU. The air intake system consists of the subsequentcomponents: Air Intake Air Intake Diverter Air Intake Flap Air Intake Flap Actuator [516KB] Air Intake Duct

The Air Intake Diverter and the Air Intake are installed in the lower section ofthe fuselage in front of the forward firewall of the APU compartment (FR95).The air flows through the Air Intake Duct from the Air intake to the Inlet PlenumChamber of the APU.The Air Intake has an Air Intake Flap which is in the closed position when theAPU does not operate. The Air Intake Flap Actuator moves the Air Intake Flapto the appropriate position. The flap actuator receives the command signalsfrom the ECB 59KD and sends the flap position signals back to the ECB.

Air Intake DiverterThe Diverter Case which has an elliptic shape is riveted to the fuselage forwardof the air intake. The Diverter Plate is installed with screws onto the Divertercase. The Air Intake diverter has two main tasks:During the flight, the Diverter increases the ram air recovery as it diverts thelow energy part of the boundary layer.On the ground and in the flight, the diverter (in conjunction with the fluidgutters) prevents fluids flowing along the fuselage from entering the Air Intake.

Air Intake FlapThe Air Intake Flap is operated by the Air Inlet Flap Actuator and closes oropens the Air Intake. The Flap opens prior APU starting and is closed when theAPU does not operate.

Air Intake Flap ActuatorThe Air Intake Flap Actuator moves the air Intake and holds it in the open orclosed position. The Actuator is controlled and monitored by theECB (Electronic Control Box). It is possible to manual override the Air IntakeFlap Actuator in open or closed position by a Manual Drive Shaft, as describedin the AMM (Aircraft Maintenance Manual).Air Intake DuctThe air intake duct is made as an aerodynamically shaped resonatortypemuffler. The purpose is to decrease the noise which is caused by the airflowthrough it. Adjustable tierods hold the air intake duct in the correct position.IndicationThe Flap open position is indicated on the APU System Display by a greenFLAP OPEN message. In all other cases there is no indication shown.

FLAP OPEN

3

5 7 11

600

EGT C


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A334-200/300GTCP 331350C

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AIR INTAKE DIVERTER

DIVERTER PLATE

DIVERTER CASE

ACTUATORMANUAL DRIVE

AIR INTAKE FLAPACTUATOR [516KB]

AIR INTAKE DUCT(APPROX. 34 KG)

AIR INTAKE FLAP& ACTUATOR

AIR INTAKE

AIR INTAKE FLAP


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Figure 14 Air Intake System


A334-200/300GTCP 331350C

4916


AIR INTAKE SYSTEM OPERATIONGeneralThe Intake Flap Actuator is a 28 VDC Linear Actuator with a ThermalOverload Switch and integrated Brake.The ECB 59KD supplies the necessary electrical power for the operation to theair intake flapactuator 516KB. The two limit switches and the two positionswitches control the position of the air intake flapactuator.

Operation

FLAP OPEN COMMANDWhen you push the MASTER SW P/BSW 14KD to the on position on theoverhead panel 215VU, the ECB [59KD] is energized and supplies 28 VDCelectrical power to the DC motor of the flap actuator which operates and movesthe air intake flap to the open position. The ECB receives the following signalsfrom the actuator: Air Intake Flap Open Air Intake Flap Closed Air Intake Flap Movement

FLAP CLOSE COMMANDThe ECB controls the air intake flap actuator to extend (close the flap) when: the APU did not operate and you push the APU MASTER SW P/BSW 14KD

on the overhead panel 215VU to the reset position the APU speed N decreases to less than 7 % during the APU shutdown

sequence an APU auto shutdown sequence or an APU emergency shutdown is

initiated by the ECB An ASD (Auto Shut Down) is caused with running APU (N > 7%) and

Inlet Flap not fully open.

Indicating FLAP OPEN is indicated in green lettering on the

ECAM (Electronic Centralized Aircraft Monitoring) APU System Displaywhen the ECB receives a 28 VDC FLAP OPEN signal from the retractedposition switch on the flap actuator.

When the ECB receives a FLAP NOT OPEN ground signal from theRetracted Position Switch on the flap actuator, it transmits no flap signal tothe EIS. In this case there is no flap position indication on the APU systempage.

When the ECB finds a flap actuator fault during the APU start sequence, itstarts the APU ASD (Auto Shut-Down) sequence and you will get thesubsequent indications in the cockpit.

On the APU MASTER SW P/BSW 14KD on the overhead panel 215VU theamber FAULT light comes on

On the APU START P/BSW 2KA on the overhead panel 215VU the blueON light goes off. On the master caution P/BSWs on the glareshield panels 411VU and

412VU the amber MASTER CAUT indications come on A single chime is heard On the EIS Engine/Warning Display (EWD):

APU FAULT AUTO SHUT DOWN MASTER SW ..........OFF

On the EIS System Display (SD): STATUS INOP SYS APU

Flap Actuator FaultThe ECB generates this fault:

the travel time is: t > 29sec the actuator has a open/short circuit.


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QUANNoteIntake flap ko mo fully thi apu se auto shutdown


A334-200/300GTCP 331350C

4916


ECB 59KD

SYSTEM DISPLAY 300VU

FAULT

ON/R

APUMASTERSWITCH

5000VE

1KD

2KD4KDAPU MAIN28VDC

309PP

215VU

14KD

(ALL POSSIBLEINDICATIONS SHOWN)

LABEL 37

FLAP OPENCOMPLETE

BIT 14

LABEL 37

FLAP CLOSECOMPLETE

BIT 15 FLAPOPEN/CLOSESIGNALLOGIC

FLAP CLOSE

FLAP MOVE

FLAP OPEN

RELAY

PUT COMPLETE

SHUTDOWN

30s

FLAP OPEN COMMAND

SHUTDOWN30s

FLAP CLOSE COMMAND

MASTER SWOFF

APU

N 7

28VDC28VDC

SIGNAL

SIGNAL

SIGNAL

UNSD

M

M

UNSD

BRAKE

UNSD

OPEN

UNSD

AIR INTAKE FLAP ACTUATOR516KB

FLAP OPEN

CLOSE

OVHT SW


Page 29Figure 15 Air Intake Flap Control

AUXILIARY POWER UNITOIL

A334-200/300GTCP 331350C

4990

4990 OILINTRODUCTION

PurposeThe self contained oil system lubricates, cleans and cools the APU bearingsand accessory gearbox. The oil system is monitored by the ECB (ElectronicControl Box) which receives temperature, pressure and quantity signals.To help cold starting, a deoiling valve is mounted on the oil pump inlet. The oilis also used to cool and lubricate the gearbox mounted Generator as well asthe Starter Motor Clutch.An air Oil Cooler in conjunction with a cooling fan is used to cool the APU oiland to ventilate the APU compartment.


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AUXILIARY POWER UNITOIL

A334-200/300GTCP 331350C

4990

LUBRICATIONMODULE

TEMPERATURE

PRESSURE

QUANTITY

ELECTRONICCONTROLBOX

DE-OILINGVALVE

GENERATOR

ENGINE BEARINGSACCESSORYGEARBOX

OILCOOLER

STARTERCLUTCH


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COMP

Figure 16 Oil System Design

AUXILIARY POWER UNITOIL SYSTEM

A334-200/300GTCP 331350C

4990


SYSTEM DESCRIPTIONPurposeThe oil system supplies the oil which lubricates and cools the APU and theAPU generator.

General The oil system has the following subsystems: Storage and Distribution System Oil Indicating System Low Oil Pressure and High OilTemperature Warning System Oil Heating System

Storage and DistributionThe oil is stored in the lower part of the gearbox (approximately 7.5 liters). Forgravity oil tank servicing, there is a filler cap and a sight glass attached on thegearbox. A fill and overflow port provides for oil pressure filling. An Oil PumpModule is mounted onto the AGB (Accessory Gear-Box) in order to supply thebearings and gears with oil and return it back into the gearbox. Filtered,temperature and pressure regulated oil is supplied to: the Engine the APU Generator

The system has: an Integral Oil Reservoir with an Electrical Chip Detector and a

Low Oil Temperature Sensor an Oil Pump Module with Oil Filters an Oil cooler

The APU has three oil sumps: the Gearbox Sump the Mid Sump the Aft Sump

The Gearbox Sump is a wet sump which is also the Integral Oil Reservoir. TheMid Sump and the Aft Sump are scavenged sumps. The three sumps have nodirect connection between each other.

Oil Indicating SystemThe oil indicating system indicates if the oil level in the integral oil reservoir isnot sufficient or if an oil servicing is necessary. When the APU does not run,the ECB monitors the status of the Low Oil Quantity (LOQ) switch.LOP and HOT Warning SystemThe LOP (Low Oil Pressure) and HOT (High Oil Temperature) Warning Systemtogether with the ECB monitor the APU oil pressure and the oil temperature.They also monitor the temperature of the APU generator scavenge oil. Thesystem protects the APU against low oil pressure and high oil temperature.When the ECB receives the low oil pressure or a high oil temperature signal, itstarts the APU automatic shutdown sequence (if it is not inhibited).Oil Heating SystemAn APU oil heater is attached to the lower accessory gearbox. The APU oilheater increases the temperature of the oil in the APU gearbox oil reservoirwhen the APU is not in operation and the oil temperature is too low.


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AUXILIARY POWER UNITOIL SYSTEM

A334-200/300GTCP 331350C

4990


S

GEA

RS

STARTER

ELECTRONICCONTROL BOX

OIL PUMPMODULE

FWDSUMP

AFTSUMP

GEN

ACCESSORYGEARBOX

RETURN

REGULATEDPRESSUREPUMP INLET

SCAVENGEGEN TEMPSENSOR

LOP HOT

CHIPDET

OIL QTYLOT

SNSROIL

HEATER

OIL COOLER

GEN OILFILTER

SCV OILFILTER

DE-OILINGSOL-VALVE


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COMP

Figure 17 Oil System Schematic

AUXILIARY POWER UNITOIL STORAGE AND DISTRIBUTION

A334-200/300GTCP 331350C

4991


4991 OIL STORAGE AND DISTRIBUTIONSTORAGE SYSTEM DESCRIPTIONGeneralThe lower part of the Accessory Drive Gearbox is the Integral Oil Reservoir ofthe APU.The subsequent components are installed onto the Accessory Drive Gearbox: Gravity Fill Port and a Pressure Fill Port Oil Level Sight Glass Oil Quantity Transmitter Low Oil Quantity Switch Low Oil Temperature Sensor Electrical Chip Detector with Drain Plug Oil Heater Air/Oil Separator

Gravity and Pressure Fill PortThe Gravity Fill Port and Pressure Fill Port are provisions for APU oil servicing.The sight glass is used for visual oil level check.

Oil Quantity TransmitterThe Oil Quantity Transmitter supplies an electrical signal to the ECBconcerning oil level status. This information is indicated on the APU SystemDisplay when the APU is stopped and the aircraft is on ground.

Low Oil Temperature SensorThe Low Oil Temperature Sensor measures the temperature of the oil in thereservoir. The ECB uses this signal for reducing the load of the Oil PumpModule and Starter, by energizing the normally closed De-Oil Solenoid Valveduring cold oil conditions. In this case oil from the oil pump outlet returns to thepump inlet and mixes with the inlet oil, thus the pump outlet is depressurized.

Electrical Chip DetectorThe Electrical Chip Detector is is mounted at the lowest point on the gearbox. Itis of the magnetic type. The chip detector collects magnetically the metallicparticles from the oil sump, the electrical contact gap of the Chip Detector isopen until sufficient quantity of particles is accumulated to close the gap andprovide a signal to ECB.The chip detector is monitored during IOT. When the Chip Detector is faulty, itwill be stored as a CLASS-2 fault with a CMS messageOIL CHIP DETECTION.NOTE: Oil Chip Detection may lead to an APU Auto Shutdown. Refer to

the TSM (Trouble Shooting Manual).Oil HeaterAn Oil Heater is used to warm up the reservoir oil during cold soak conditions.The Heater heats up the oil in the gearbox to a temperature of approximately43 C when the APU Master Switch is off.

Air/Oil SeparatorThe oil reservoir has a connection to the ambient air through an air/oilseparator. The air/oil separator is connected through a gearbox vent line to theAPU exhaust cone.


Page 34

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4991


AIR/OILSEPARATORPORT

OIL HEATER

ELECTRICAL CHIPDETECTOR ANDDRAIN PLUGLOW OILQUANTITY

SWITCH

LOW OILTEMPERATURESENSOR


Page 35Figure 18 Oil System Component Location (1/2)


A334-200/300GTCP 331350C

4991


DISTRIBUTION SYSTEM DESCRIPTIONGeneralThe subsequent components make the oil distribution system: Oil Pump Module The Oil Cooler Oil Filters

Oil Pump ModuleThe Oil Pump Module removes the oil from the oil reservoir by suction. Itregulates the oil pressure and supplies the temperature regulated and filteredoil to the lubrication points of the: Engine Load compressor Accessory Drive Gearbox APU Generator

The Oil Pump Module removes the oil by suction (the scavenged oil) from the: Mid Sump Aft Sump APU Generator

During cold weather starting conditions, the ECB will automatically open theDe-Oiling Solenoid Valve to reduce starter motor and lube pump load causedby cold oil.The scavenged oil from the Mid Sump and the Aft Sump is returned to the oilreservoir. The generator scavenge oil is supplied to the Starter Clutch Sprags.The oil which lubricates the gears and bearings of the gearbox, is returned tothe reservoir by gravity.

Oil CoolerThe Oil Cooler is mounted on the left air inlet plenum. It is an Oil/Air HeatExchanger which receives the cooling air from the Cooling Fan (Ref.4952) todecrease the temperature of the oil.A thermal bypass valve installed at the oil cooler inlet prevents cold oil frompassing the Heat Exchanger or bypasses oil When the Oil Cooler is blocked.

Oil FiltersThe distribution system has two oil filters: Lubrication Oil Filter Generator Scavenge Oil Filter

The filters remove unwanted materials from the oil. The Lubrication Oil Filtercleans all the lubrication oil before it is supplied to the lubrication points.The Generator Scavenge Oil Filter cleans unwanted materials from thegenerator scavenge oil. This makes sure that no contaminated oil returns fromthe Generator to the oil reservoir and the Starter Clutch Sprags are lubricatedduring the APU shutdown.

Distribution System MonitoringThe ECB monitors the lubrication oil temperature and pressure. A HighOilTemperature Sensor measures the temperature of the oil and transmits ananalog signal to the ECB. If the oil temperature is too high, the ECB starts anAPU automatic shutdown (if it is not inhibited).A LowOil Pressure Switch monitors the regulated oil pressure. When the LowOilPressure Switch finds that the oil pressure is too low, it transmits a discretesignal to the ECB which will perform an APU automatic shutdown (if it is notinhibited.A Generator OilTemperature Sensor is installed on the APU generator. Itmeasures the oil temperature at the generator oil outlet and transmits it to theECB. When the generator return oil is too hot, it starts an APU automaticshutdown (if it is not inhibited).


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4991


OILCOOLER

HIGH OIL TEMPERATURE SENSOR

LOW OIL PRESSURE SWITCH

GENERATOR SCAVENGEOIL FILTERLUBRICATIONOIL FILTER

GRAVITY FILLPORT


Page 37

FILTER

LOP/HOT

Figure 19 Oil System Component Location (2/2)


A334-200/300GTCP 331350C

4991


OIL SERVICINGPrecautionsWARNING: USE THE CORRECT PERSONAL PROTECTION. OIL CAN

HAVE AN ADDITIVE CALLED TRICRESYL PHOSPHATE IN IT.THIS CHEMICAL IS AN ASPHYXIANT, IT IS POISONOUS ANDCAN BE ABSORBED THROUGH THE SKIN. ALSO HOT OILCAN POSSIBLY CAUSE BAD BURNS.

GeneralReservoir oil servicing is possible by gravity fill or with a pressure fill device. Onthe left side of the gearbox the subsequent ports are installed: Gravity Fill Port Pressure Fill Port Pressure Fill Overflow Port

The gravity fill port has an oil sight glass and an oil scupper. The scupperprevents that oil flows on to the APU and into the APU compartment during thegravity oil fill.

PolicyYou can read the oil level on the Oil Sight Glass. It must be between the FULLand the ADD mark. The oil quantity at the FULL mark is 7.3 l, at the ADD mark4.1 l. The difference between the two marks is 3.2 l.NOTE: The maximum allowable oil consumption is 9.5 cc/hr for a new

APU.You can also fill the oil reservoir with a pressure fill device through the pressurefill port. The oil which is more than the FULL mark limit flows through theoverflow port back to the reservoir of the fill device.The oil drain plug is installed at the lowest point of the integral oil reservoir. Theelectrical chip detector is installed in the drain plug. You can remove the drainplug with the chip detector installed. You can also remove the chip detectorwithout the drain plug. The drain plug has a check valve which closes whenyou remove the chip detector. Thus it is not necessary to drain the oil reservoirfor a visual check of the chip detector.

IndicatingWhen the oil quantity decreased to 4.1 l or less, the Low Oil Quantity Switchtransmits a signal to the ECB. If the APU is stopped and the aircraft is on theground, the APU system page of the EIS (Electronic Instrument System)shows the LOW OIL LEVEL advisory message in pulsing green. If the oilquantity is more than the set minimum, nothing is shown on the display.


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CAUTION: OIL CONSUMPTION IS THE TERM USED FOR THE INTERNAL LOSS OF OILFROM BEARING SEALS AND AIR/OIL SEPARATOR DURING APUOPERATION. EXTERNAL LEAKS ARE NOT PERMITTED. YOU MUSTCORRECT EXTERNAL LEAKS AND CLEAN THE APU, APU COMPARTMENTAND APU AIR INTAKE IMMEDIATELY IF CONTAMINATED. IF THE OILCONSUMPTION IS HIGHER THAN THE GRAPH-A LIMIT, OR THERE IS ASUDDEN INCREASE, YOU MUST DO THE OIL CONSUMPTIONMONITORING VERY CAREFULLY TO PREVENT BAD APU DAMAGE.

NOTE: The added oil (vertical scale) is the total quantity of oil which was added tothe oil reservoir in order to compensate for the APU consumption duringan operating time period (horizontal scale).

Quarts Liters

ADD

ED O

IL (C

OMMU

TATI

VE)

APU OPERATING TIME (HOURS)

OIL PRESSUREFILL PORT

PRESSUREFILLOVERFLOWPORT

SIGHT GLASS

GRAVITY FILLPORT

GRAPH-A

GRAPH-B

Oil Quantity in the APU oil reservoir issufficient for minimum 14 hours APUoperation without preflight service if noLOW OIL LEVEL Indication is shown

Oil Quantity in the APU oil reservoir is sufficientfor 14 hours APU if serviced before flight to theFULL MARK on the oil sight glass

Oil quantity in the APU oilreservoir is not sufficientfor 14 hours APU operation


Page 39Figure 20 Reservoir Oil Servicing

AUXILIARY POWER UNITSTORAGE AND DISTRIBUTION

A334-200/300GTCP 331350C

4991


COMPONENT DESCRIPTION

OIL PUMP MODULEGeneralThe Oil Pump Module is mounted on the front side of the accessory drive gearbox and driven by the AGB. The module consists of: Three Lubrication Elements Two Generator Scavenge Elements One Aft Sump Scavenge Element One Mid Sump Scavenge Element Pressure Relief Valve Pressure Regulator Valve DeOiling Solenoid Valve Lubrication Filter Generator Scavenge Filter

Lubrication & Scavenge ElementsThe 3 lubrication elements are identical and work in parallel. Thus it is notnecessary to pressurize the gearbox at high altitudes to make sure that thesupply of lubrication oil is sufficient.The 2 generator scavenge elements are identical and work in parallel. Thus theoil which lubricates and cools the APU generator is scavenged accurately.The aft sump scavengeelement and the mid sump scavengeelement supplythe scavenged oil directly to the oil reservoir.

Oil Pressure Relief & Pressure Regulating ValveThe Oil Pressure Relief Valve is of the poppet and seat type. It is installed inparallel to the lubrication items and opens at a pressure difference of 200 psi.The Oil Pressure Regulating Valve is of the spool and sleeve type. It is installedin parallel to the lubrication elements and controls the oil pressure to 65 5 psi.


Page 40


A334-200/300GTCP 331350C

4991


RETURN

REGULATED PRESSUREPUMP INLETSCAVENGE

SW

1KT

N < 65%ALTITUDE> 31,000 ftAPU STARTOIL TEMP < -6.7CN < 60%

APU ROLLDOWN

N > 95%LOP SW

LOT > -4C

HIGH OILTEMPERATURE

GEN HIGH OILTEMPERATURE

OIL CHIPDETECTION

LOW OILPRESS S/D

LOW OILQUANTITY

ECB 59KD

SDE-OILINGSOLENOIDVALVE

MIDSUMP

AFTSUMP

OIL PUMPMODULE

ELECCHIPDET[59KT5]

OILHEATER[59KT16]

LOW OILTMP SNSR[59KT9]

LOW OILQTY SW[59KT8]

GEN

GENSPLINESHAFT

COOLINGFAN

HIGHSPEEDPINION

FWDLOADCOMPHOLD

GENGEAR

STARTERSPRAG

CLUTCH

STARTERCLUTCHGEARS

OIL RESERVOIR AIR/OILSEPARATOR

[4KD]

GENERATORSCAVENGE-OILFILTER

LOW OILPRESS SW[59KT14]

LUBRICATIONOIL FILTER

OIL COOLER& THERMALBYPASS VALVE

COOLING FAN

HIGH OILTEMP SNSR[59KT11]

GEN OIL TEMP SENSOR


Page 41Figure 21 Oil System Schematic


A334-200/300GTCP 331350C

4991


Oil FiltersBoth, the Lubrication Oil Filter and the Generator Scavenge Oil Filter areequipped with a magnetic type differential pressure indicator. It gives you avisual indication when the filter element is clogged. When the pressuredifference across the element is 33 5 psi a red indicator extends out of theindicator housing. It is magnetically locked out and remains in this positioneven when the oil pressure decreases at APU shutdown. To reset the indicatorpin you push it manually into the housing.A thermal lockout device stops the clogging indicator operation until the oiltemperature is more than 37.7 C. This avoids an irregular clogging indicationcaused by the higher viscosity of cold oil.The Lubrication Oil Filter has a Filter Bypass Valve which opens when the filterelement is fully clogged. Then the oil does not flow through the filter element,but the APU receives lubrication oil further on.The Generator Scavenge Oil Filter has a Pressure Relief Valve which openswhen the filter element is fully clogged. The generator scavenge oil then flowsto the oil cooler inlet line. Thus the generator scavenge oil is cooled and thencleaned by the Lubrication Oil Filter.


Page 42


A334-200/300GTCP 331350C

4991


OIL PRESSURERELIEF VALVE

OIL PRESSUREREGULATOR VALVE

LUBE OIL FILTERBYPASS VALVE

DE-OILINGSOLENOIDVALVE

GEARBOXDRIVE

FCU DRIVE

FILTERCLEAR

FILTERCLOGGED


Page 43

CLOGGING

MODULE

Figure 22 Oil Pump Module


A334-200/300GTCP 331350C

4991


OIL COOLER AND THERMAL BYPASS VALVE

Oil CoolerThe oil cooler is of the platefin design, with a noncloggingcontaminationresistant wavyfin core. It has two primary components: Air/Oil Heat Exchanger Thermal Bypass Valve

NOTE: A serviceable Oil Cooler will keep the oil temperature below thelimit of 140 C during all operation conditions.

Thermal Bypass ValveThe Thermal Bypass Valve is of the twostage poppet type. The first stage hasa Thermal Expansion Element for the oil temperature regulation.When the Thermal Bypass Valve is fully open (cold oil), the oil does not flowthrough the heat exchanger until the oil temperature is more than 60 C. At thispoint the Expansion Element starts to close the valve. At an oil temperature of77 C the valve is fully closed and all the oil flows through the heat exchanger.The second stage has a Pressure Relief Valve in order to protect the HeatExchanger from high oil pressure caused. It is spring loaded closed.In case of an obstructed Oil Cooler it opens at a differential pressure of 50psid.There is no oil flow through the Heat Exchanger, the oil flows directly to thelubrication oil filter.


Page 44


A334-200/300GTCP 331350C

4991


OILCOOLER

THERMAL BYPASSVALVE

A

A

Air Out

Air In


Page 45

1 / 3


A334-200/300GTCP 331350C

4991


Oil In

Oil Out

EXPANSIONELEMENT

THERMAL BYPASS VALVE

OILCOOLER

OILCOOLER

THERMAL BYPASSVALVE

A

A

SECTION A-A

Air Out

Air In


Page 45

2 / 3


A334-200/300GTCP 331350C

4991


Oil In

Oil Out

EXPANSIONELEMENT

THERMAL BYPASS VALVE

OILCOOLER

OILCOOLER

THERMAL BYPASSVALVE

A

A

SECTION A-A

Air Out

Air In

THERMAL BYPASS VALVE FUNCTIONS

Thermal Function:Expansion Element starts to closethe Valve at 60 CValve is fully closed at 77 C (No Bypass)Bypass Function:Valve opens at 50 psid over HX(Oil Cooler Bypass)


Page 45Figure 23 Oil Cooler Function

3 / 3


A334-200/300GTCP 331350C

4991


DEOILING SYSTEM OPERATION

Low Oil Temperature SensorThe low oiltemperature sensor is installed on the gearbox housing andmeasures the temperature in the oil reservoir. The temperature signal istransmitted to the ECB. When the ECB receives the start signal from theSTART P/BSW 2KA in the cockpit and finds that the oil temperature is lessthan 6.7 C or the altitude is above 31000 ft, it energizes the DeOilingSolenoid and the normally closed DeOiling Valve opens.Oil from the oil pump outlet (to the oil cooler) returns to the pump inlet andmixes with the inlet oil, the pump outlet is depressurized. This reduces theload of the oil pump module and thus also for the APU starter motor which iscaused by the high viscosity of the cold oil. The ECB deenergizes theDeOiling Solenoid after the APU reaches 60% speed (65% speed in case ofhigh altitude).The ECB also carries out deoiling at every APU shutdown between 95% and7% APU speed. This makes sure that the scavenge elements of the oil pumpcan remove the oil from the sumps during the shutdown. This also reduces theload of the starter motor at the subsequent APU start.

DeOiling Solenoid ValveThe DeOiling Solenoid Valve is mounted at the Oil Pump Module which isnormally spring loaded closed. It is a solenoid operated poppet valve and isoperated from the ECB under the following conditions: APU Start when Oil Temperature 7%


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A334-200/300GTCP 331350C

4991


DE-OILING VALVE(NORMALLY CLOSED)

OIL TO THEOIL COOLER

OIL FROM THEOIL COOLER

ECB

OIL PUMPMODULE

S

RETURNRETURN

REGULATEDPRESSURE

PUMP INLET


Page 47Figure 24 De-Oiling System Schematic



4910 POWER PLANT4912 APU MOUNTS4920 ENGINE4980 EXHAUST4917 POWER PLANT DRAIN SYSTEM4916 AIR INTAKE SYSTEM4990 OIL4991 OIL STORAGE AND DISTRIBUTION4993 OIL INDICATING4994 LOP AND HOT WARNING4996 APU OIL HEATING4930 ENGINE FUEL AND CONTROL4934 APU FUEL LP WARNING4950 AIR4951 BLEED AND SURGE AIR4952 ACCESSORY COOLING

AUXILIARY POWER UNITOIL INDICATING

A334-200/300GTCP 331350C

4993


4993 OIL INDICATINGDESCRIPTION

GeneralThe Oil Indicating System monitors the oil quantity in the oil reservoir and givesrespective indication on the APU System Display in static condition, i.e. whenthe APU does not operate.

Low Oil Quantity SwitchThe primary component within the Oil Indicating System is the Low Oil QuantitySwitch. It is installed at the bottom of the housing of the accessory drivegearbox. The switch stays up into the oil in the integral oil reservoir andtransmits the low oilquantity signal to the ECB, if the oil quantity is at or belowthe set minimum of 4.1 l. The set minimum agrees with the ADD mark on theoil sight glass on the gravity oil fillport.When the ECB receives a lowoil quantity signal from the low switch, ittransmits the signal to the: EIS (Electronic Instrument System) CMS (Central Maintenance System

You can read the oil quantity information on the EIS SD (System Display) andthe MCDUs (Multipurpose Control & Display Units) in the cockpit on the: APU page on the System Display APU SERVICE DATA page on the MCDU

APU GEN62115400

%VHZ

BLEED35 PSI

LOW OILLEVEL

AVAIL

APU

0

10N%

100

3

5 7 11

600

EGT C

Figure 25 Oil Quantity Indication


Page 48


A334-200/300GTCP 331350C

4993


LOW OILQUANTITYSWITCH


Page 49Figure 26 Low Oil Quantity Switch


A334-200/300GTCP 331350C

4993

LOW OIL QUANTITY SWITCHConstructionThe LowOil Quantity Switch has an aluminum body. It holds: an Electrical Connector a tube with a Float Assembly and Permanent Magnets the two DualReed Switches

In the lower part of the tube the two dualreed switches are installed. There isalso a welded aluminum float inside the tube on which an alnico V-magnet isinstalled. It is a permanent magnet.The float is immersed in the oil. When the oil quantity is at the permittedminimum, the magnet of the float opens the two dualreed switches. Thedualreed switches are redundant. They are connected in parallel and make anOR-gate.

OperationWhen the oil quantity in the reservoir decreases to 4.1 l, the magnet on thefloat opens the two dualreed switches. The ECB receives the discrete opensignals. A signal from one of the two dualreed switches is sufficient for theECB to operate.

ControlThe ECB transmits the lowoil quantity signal to the EIS and the CMS whenthe subsequent signals are given: LowOil Quantity Signal and Oil Temperature is less than 65.55 C and Aircraft on Ground

IndicatingOn the APU Page on the EIS System DisplayThere is no oil level advisorymessage on the APU page of the SD, if the oillevel in the APU oil reservoir is more than the set minimum. You can read theLOW OIL LEVEL advisory message if the oil level in the APU oil reservoirdecreased to the set minimum or below this level. The LOW OIL LEVELadvisory message is pulsing green.On APU Service Data PageYou can read an OIL LEVEL O.K. indication, if the oil level in the APU oilreservoir is more than the set minimum.You can read an OIL LEVEL LOW indication, if the oil level in the APU oilreservoir decreased to the set minimum or below this level.


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A334-200/300GTCP 331350C

4993

28VDC

309PP2KD

APU CTL1KD

MAIN SUPPLY

59KD

ARINC BUSSES

4KD

RELAYAPU MAIN

ZONE APU

LOW OILQUANTITYSWITCH 59KT8

5000VE

FAULT

ON/R

215VU

2LP3ANNLTTRANSFORMER

BOARDANN LTAND INTFC

1LP3

14KD APUMASTER SWITCH

FLOAT ASSY

PERMANENTMAGNETSREADSWITCHES

ALUMINUMBODY

LOW OIL QUANTITY SWITCH

ECBEIS

CMS


Page 51Figure 27 LOQ-Electrical Schematic



4912 APU MOUNTS4920 ENGINE4980 EXHAUST4917 POWER PLANT DRAIN SYSTEM4916 AIR INTAKE SYSTEM4990 OIL4991 OIL STORAGE AND DISTRIBUTION4993 OIL INDICATING4994 LOP AND HOT WARNING4996 APU OIL HEATING4930 ENGINE FUEL AND CONTROL4934 APU FUEL LP WARNING4950 AIR4951 BLEED AND SURGE AIR4952 ACCESSORY COOLING4970 INDICATING

AUXILIARY POWER UNITLOW OIL PRESSURE AND HIGH OILTEMPERATURE WARNING

A334-200/300GTCP 331350C

4994


4994 LOP AND HOT WARNINGSYSTEM OPERATIONGENERALThe LOP (Low Oil Pressure) and HOT (High Oil Temperature) Warning Systemhas the subsequent primary components: High Oil Temperature Sensor (HOT SNSR) Low Oil Pressure Switch (LOP SW)

The HOT SNSR and the LOP SW are installed downstream of the oil coolerand the oil pressure regulation valve. They are installed in a manifold which is apart of the line to the mid and the aft sump.

HIGH OIL TEMPERATURE SENSOR

ConstructionThe HOT SNSR is a RTD (Resistive Temperature Device). It is a nickelwirethermalresistant element which can operate in the subsequent temperaturerange from 53.9 C to +250 C). This makes an input operating range for theECB of 73 to 200 ohms. The sensor has a stainless steel body with a copper tip which protects theelectrical components against oil, water and moisture.

OperationThe HOT SNSR measures the oil temperature downstream of the oil cooler. Ittransmits the analog oil temperature signal to the ECB. This starts the APUautomatic shutdownsequence (if it is not inhibited) when: Oil Temperature >147.2 C for 10 seconds and APU Speed >95 %

MonitoringThe sensor is monitored during PUT and Selftest. If the sensor faulty, it will bestored as a CLASS-3 failure with a CMC message:HIGH OIL TEMP SNSR (59KT11).

LOW OIL PRESSURE SWITCH

ConstructionThe LOP SW has a microswitch with normally open contacts. This decreasesthe consumption of electrical power and the corrosion of the contacts. The LOPSW has a hermetically sealed stainlesssteel body which protects the electricalcomponents against oil, water, and moisture.

OperationThe LOP SW monitors the pressure downstream of the oilpressure regulationvalve. When the LOP SW detects low oil pressure, the microswitch closes andmakes a ground connection which is transmitted as a discrete signal to theECB. The ECB starts the APU automatic shutdownsequence (if it is notinhibited) when: APU Speed >95% and it receives a low oilpressure signal for:

15 seconds when APU oil temperature < 3.9 C 1 second when APU oil temperature > 3.9 C

MonitoringThe switch is monitored during PUT and Selftest. If the switch is faulty, it will bestored as a CLASS-2 failure with a CMC message:LOW OIL PRESS SW (59KT14).GENERATOR HIGH OIL TEMPERATURE SENSOR

FunctionAdditional to the HOT SNSR and the LOP SW there is the Generator High OilTemperature Sensor (GEN HOT SNSR) incorporated in the APU Generator.The ECB receives its analog signal and thus it monitors the temperature of thegenerator scavenge oil. If the generator scavenge oiltemperature is too highthe ECB starts the APU automatic shutdownsequence (if it is not inhibited)when the generator oil temperature is more than 185 C for 1 second. Thisprotects the APU Generator from possible damage.


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QUANNoteTruong hop nay se khong tu dong shutdown trong cac phase 2 - 9, REF AMM 49 - 61- 00

AUXILIARY POWER UNITLOW OIL PRESSURE AND HIGH OILTEMPERATURE WARNING

A334-200/300GTCP 331350C

4994


28VDC

309PP1KD

ECB SPLY2KD

APU CTL4KD APUMAIN RELAY

FAULT

ON/R

215VU

2LP3ANN LTTRANSFORMER


ECB

59KD

EIS

CMS

5000VE

MASTER SWITCH14KD APU

1LP3

SWITCH SENSOR

APU ZONE 315

LOP HOT

APU PANEL

HIGH OILTEMPERATURESENSORLOW OILPRESSURESWITCH


Page 53Figure 28 LOP/HOT-Warning System



4920 ENGINE4980 EXHAUST4917 POWER PLANT DRAIN SYSTEM4916 AIR INTAKE SYSTEM4990 OIL4991 OIL STORAGE AND DISTRIBUTION4993 OIL INDICATING4994 LOP AND HOT WARNING4996 APU OIL HEATING4930 ENGINE FUEL AND CONTROL4934 APU FUEL LP WARNING4950 AIR4951 BLEED AND SURGE AIR4952 ACCESSORY COOLING4970 INDICATING4971 POWER INDICATING

AUXILIARY POWER UNITAPU OIL HEATING

A334-200/300GTCP 331350C

4996


4996 APU OIL HEATINGOIL HEATING DESCRIPTION

GeneralThe primary component of the APU Oil Heating System is the Oil Heater. TheHeater incorporates an Oil Temperature Switch, which monitors the oiltemperature in the reservoir of the APU gearbox.

Power SupplyThe APU Oil Heater operates only if the APU Master Switch is off. The oilheater system gets the electrical power from the AC system of the aircraft. Itsupplies 115 V AC to the SERVICE BUS 113XP through the circuit breaker1KT, a bus and the relay 4KD to the APU oil heater 59KT16.

FunctionIf the oil temperature decreases below 21.1 C, the temperature switch closesand 115 V AC is supplied to a heater coil. This increase the APU oiltemperature to more than the APU compartment temperature during cold soakcondition.When the oil temperature increases to above 43.3 C, the temperature switchopens, and stops the 115 V AC supply to the heater coil.

MonitoringThe APU Oil Heater is monitored by the ECB but not controlled. When the ECBreceives an APU Oil Heater failure message, a CLASS-2 failure is shown onthe MCDU (Multipurpose Control and Display Unit):APU OIL HEATER (59KT16).


Page 54

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AUXILIARY POWER UNITAPU OIL HEATING

A334-200/300GTCP 331350C

4996


GEARBOX

OIL HEATER

CTL SUPPLY SUPPLY SUPPLYMAIN MODE

COMINTRPT

NO VDC BCL APU BCL APU VMREF BAT REF BAT APU APU

CNTOR

DC SUPPLY

APU

HEATEROIL SURGE CTL VALVE HEATER

APU OIL HEATER

5127VCP1

P1

310W

40W

B2B3B1

X1X2

SCHO1

4961SCH01

UNSD

113XPC115VACSVCE BUS 1245818

9

10

4KD RELAYAPU MAIN5000VE1624961

5005VE273

59KT16OIL HEATERAPU 310

A

A

A

A2453SCH061 2

3

5

5

1KT C/BAPU OIL HEATER5000VE162

BULK CARGOCOMPARTMENT

APU BOX 5000VE


Page 55Figure 29 Oil Heater

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4980 EXHAUST4917 POWER PLANT DRAIN SYSTEM4916 AIR INTAKE SYSTEM4990 OIL4991 OIL STORAGE AND DISTRIBUTION4993 OIL INDICATING4994 LOP AND HOT WARNING4996 APU OIL HEATING4930 ENGINE FUEL AND CONTROL4934 APU FUEL LP WARNING4950 AIR4951 BLEED AND SURGE AIR4952 ACCESSORY COOLING4970 INDICATING4971 POWER INDICATING4972 TEMPERATURE INDICATING

AUXILIARY POWER UNITENGINE FUEL AND CONTROL

A334-200/300GTCP 331350C

4930

4930 ENGINE FUEL AND CONTROLINTRODUCTION

PurposeThe Engine Fuel and Control System supplies metered fuel to the combustor.The metered fuel is the quantity, which is mandatory for the safe and theeconomic operation of the APU. The fuel quantity supplied is in proportion tothe APU load during governed operation.

GeneralThe engine fuel and control system receives the low pressure fuel from the A/Cfuel system through the APU fuel feed line. The APU fuel feed line is installedto the trim tank line.The main components of the Fuel System are the: FCU (Fuel Control Unit) Fuel Flow Divider Assembly

The ECB computes the fuel/air ratio, corresponding to the APU load. The FCUmeters the fuel. It does this in the direct proportion to the command signaltransmitted from the ECB. The metered fuel is filtered highpressure fuel.The Fuel Flow Divider Assembly receives the metered fuel from the FCU. Itdivides the fuel and supplies it to the Fuel Manifolds in the correct sequence.Fuel pressure is also used as muscle pressure to operate the LoadCompressor IGV (Inlet Guide Vane) actuator and the SCV (Surge ControlValve) actuator.


Page 56

COMP

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A334-200/300GTCP 331350C

4930

IGVACTUATOR


FUELCONTROL

UNIT

FUELMANIFOLDS

BLEED CONTROLVALVE

SURGECONTROL VALVE

FLOW DIVIDERASSEMBLY


Page 57Figure 30 Fuel System Design


A334-200/300GTCP 331350C

4930


FUEL CONTROL SYSTEM DESCRIPTIONGeneralThe FCU (Fuel Control Unit) is the primary component of the Fuel ControlSystem. It is attached to the Oil Pump Module by a V-clamp. The FCU metersthe necessary fuel to the combustion chamber and supplies regulated fuelpressure internally to the FMV (Fuel Metering Valve), and externally to theIGVs (Inlet Guide Vanes) and SCV (Surge Control Valve) actuators.FCU Inlet FilterThe FCU Inlet FuelFilter removes unwanted materials from the fuel which issupplied from the APU fuel pumpsystem to prevent contamination of thedownstream components of the APU fuel system. It is equipped with a VisualClogging Indicator where a red indicator pin extends in case of filter clogging.In this condition an internal Bypass Valve opens to maintain fuel supply.

High Pressure Fuel PumpThe HighPressure Fuel Pump is a two gear rotary type which pumpshighpressure fuel. A shaftseal witness drainport is located on the bottom ofthe mounting flange. Fuel or oil leakage from the drain port is an indication thatthere are internal leakages. Fuel flow at 100% APU speed is 1020 kg/h at apressure of 800 psi.

Fuel Metering ValveThe fuel is metered from the Metering Valve, which is operated by anElectronic Torque Motor controlled by ECB. An increased electrical power tothe torque motor operates the metering valve and increases the fuel flow. Adecreased electrical power decreases the fuel flow. When no electrical powerfrom the ECB is supplied, the torque motor meteringvalve moves to the lowestposition to allow the minimum fuel flow.The electrical supply to the Torque Motor MeteringValve stops when the ECBreceives one of the subsequent signals: Protective Shutdown APU Normal Shutdown Overspeed Signal

Fuel Shutoff Solenoid-ValveThe Fuel Shutoff SolenoidValve is a normally closed, electrically openedsolenoid valve. During the APU start sequence, it receives a command signalfrom the ECB to open at 7 % APU speed. On normal or fault shutdowns, theFuel Shutoff SolenoidValve receives a close signal from the ECB.


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QUANHighLight

toan-ptHighlight


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4930


DMM

PCD2 AIR

PRIMARYMANIFOLD

SECONDARYMANIFOLD

FUEL CONTROL UNIT

IGVACTUATOR

SCVACTUATOR



M

DRAIN

FUEL HIGH PRESSUREMETERED FUEL

RETURN/(SCAVENGE)

REGULATED PRESSURE

S

S

FUEL TEMPSENSOR

FUELFLOWMETER

SECONDARYSEQUENCEVALVE

PRIMARYDRAINVALVE

SECONDARYDRAINVALVE

ECOLOGYDRAINSOLENOID

FUELSOLENOIDVALVE

FMV

PRESS.VALVE

FUEL PUMP

A/C AFT FUELFEED PUMPAPU LOW-PRESSUREFUEL SHUTOFF VALVE

FCU INLETFILTER

FUEL LPSWITCH

HPFILTER REG

APUSYSTEMDISPLAY

ACCUMULATOR


Page 59Figure 31 Fuel System Schematic


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4930


FUEL DISTRIBUTION SYSTEM DESCRIPTIONGeneralThe Fuel Control Unit supplies the correct quantity of fuel to the APU fueldistribution system. The fuel flows through the distribution system to thecombustion chamber where it mixes with the air and burns.The fuel distribution system also has an ecology drain system. The ecologydrain system makes sure that the fuel is removed from the fuel atomizers andmanifolds during the APU shutdown. The drain fuel is burned in the combustionchamber.

System LayoutThe fuel distribution system consists of the subsequent primary components: Primary and Secondary Fuel Manifold and Nozzles Flow Divider Assembly Ecology Drain System Fuel Temperature Sensor Fuel Flow Meter

Fuel Manifold and NozzlesThe Fuel Manifold is located around the turbine plenum. It is divided into aPrimary and a Secondary Fuel Supply, both connected to each of the 12 DualOrifice Fuel Nozzles. The fuel flows through the primary and secondary fuelmanifolds from the flow divider Assembly to the Fuel Nozzles. The fuelmanifold ensures an even fuel distribution to the nozzles.


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LP FUELFILTER

LOW FUELPRESSURESWITCH

DRAIN PORTAIR CHECKVALVE

HP-FUELFILTER

LP-FUEL FILTERCLOGGING INDICATOR

FUEL SHUTOFFSOLENOID VALVE

FUEL METERING VALVETORQUE MOTOR

LP FUEL FILTERBYPASS VALVE


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COMP (b)

COMP (a)

Figure 32 Fuel Control Unit


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4930


Flow Divider AssemblyThe Flow Divider Assembly is supplied with fuel coming from the FCU whichcontrols the fuel quantity. The Flow Divider Assembly splits the fuel into primaryand secondary fuel and supplies it to the fuel manifolds.The secondary sequencing valve permits or stops the flow of fuel to thesecondary flow path of the flow divider. The valve is springloaded closed untilthe flow of fuel has the maximum quantity of primary fuel which the FuelNozzles can atomize accurately. This makes sure that the fuel/air mixture iscorrect in the combustion chamber during the start sequence.

Ecology Drain SystemWhen the APU is stopped and no fuel is supplied, the fuel inlets of the Primaryand Secondary Drain Valves are springloaded closed. Their drain air inlets areopen and thus the drain air line is connected to the fuel manifolds. Compressordischarge air which is stored in the Air Tube enters the Fuel Manifolds whenthe Ecology Drain Solenoid Valve is commanded open by the ECB. Thusremaining fuel is blown out of the Fuel Nozzles.

Fuel Temperature Sensor and Fuel Flow MeterThe Fuel Temperature Sensor measures the fuel temperature and transmits ananalog fuel temperaturesignal to the ECB. The Fuel Flow Meter measures thequantity of the fuel which flows through the primary line of the flow dividerassembly. It transmits an analog fuel flow quantitysignal to the ECB. Thesetwo signals make the closed loop for the ECB which uses them to calculate theaccurate fuel quantity necessary for the APU start sequence.


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QUANHighLight

QUANHighLight

QUANHighLight


A334-200/300GTCP 331350C

4930


ECOLOGY DRAINCHECK VALVE

ECOLOGY DRAINSOLENOID VALVE

FUEL TEMPSENSOR

FUEL INLET


PRIMARYFLOW

SECONDARYFLOW


DUAL FUEL NOZZLE

FILTERSCREEN

FILTERSCREEN

AIRSHROUD

DUAL-ORIFICETIP ASSEMBLY

FUEL FLOWMETER


Page 63Figure 33 Flow Divider Assembly and Fuel Nozzle


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FUEL SYSTEM OPERATIONGeneralThe ECB acts on the fuel system according to two different schedules: Acceleration Schedule during Starting Speed Maintain Schedule during OnSpeed Operation

Acceleration ScheduleThe Fuel Temperature Sensor and the Fuel Flow Meter which measures thequantity of the fuel which flows through the primary line of the Flow DividerAssembly transmit analog signals to the ECB. These two signals make theclosed loop for the ECB which uses them to calculate the start fuel quantity.During APU starting sequence, when the APU shaft speed (N) is above 7%,the ECB energizes the Fuel Solenoid ShutOff Valve. Then it supplies the FMVtorque motor to provide the correct amount of fuel to comply with the ECBsmooth acceleration schedule according to: Inlet Temperature (T2) Inlet Pressure (P2) Fuel Temperature

As the FMV operates, fuel pressure opens the Pressurizing ShutOff Valveagainst spring force. Because of the low fuel flow during the start of the APU,the Secondary Sequencing Valve of the Flow Divider Assembly isspringloaded closed. The Primary Drain Valve opens the fuel inlet and closesthe Ecology Drain Air Inlet when the fuel pressure is approximately 5 psi. Thefuel flows into the Primary Fuel Manifold only, which supplies it to the PrimaryFuel Nozzles. After fuel ignition, the APU shaft accelerates, increasing HP-fueldelivered pressure. At approximately 125 psi fuel pressure downstream of theFMV, the Secondary Sequence Valve opens, allowing the Secondary FuelManifold to be supplied. The ECB continues to supply the FMV torque motor inorder to reach 100 % N speed.During all this acceleration process, the FMV LVDT feedback provides thenecessary information for the fuel closed loop control to the ECB. EGT(Exhaust Gas Temperature) is used during starting to limit the fuel schedule toprevent EGT exceedance. This EGT protection overrides the accelerationschedule.

Speed Maintain ScheduleDuring onspeed operation, the ECB controls the FMV torque motor in order tomaintain a constant 100% N speed regardless of electrical or pneumatic loadapplied to the APU. If the speed tends to decrease, due to load effect, the ECBreacts by opening the FMV more to increase the fuel flow to regain the 100%speed reference. During APU load reduction, fuel flow will be reduced toprevent the speed from exceeding 100%.


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QUANHighLight


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4930

DMM

PCD2 AIR

PRIMARYMANIFOLD

SECONDARYMANIFOLD

FCU

REG

LOW FUELPRESSURE

IGVACTUATOR

SCVACTUATOR


ECB

M

REG

DRAIN

FUEL HIGH PRESSUREMETERED FUEL

RETURN/(SCAVENGE)

REGULATED PRESSURE

M

M

S

S

FUEL TEMPSENSOR

FUELFLOWMETER


PRIMARYDRAINVALVE

SECONDARYDRAINVALVE

ECOLOGYDRAINSOLENOID

FUELSOLENOIDVALVE

FUELMETERINGVALVE

PRESSURIZING VALVEFUEL PUMP

A/C AFT FUELFEED PUMP

APU LOW-PRESSUREFUEL SHUTOFF VALVE

FCU INLETFILTER

FUEL LP-SWITCH

LOWER ECAM DISPLAY UNIT

HPFILTER

FCUCTLLOGIC

FUEL TEMP

FUEL FLOW

N%INLET PINLET TEMPFUEL TEMPEGTMES

ECSFUEL FLOW

APU STARTN>7%SHUTDOWNAPU STOP/SHUTDOWN

N>7%

N


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4930

Differential Pressure Regulation-ValveThe FCU contains a springcontrolled Differential Pressure RegulationValve.It operates with the FuelControl Torque Motor and the Pressurizing Valve.The highpressure gear pump supplies always more fuel than necessary forthe operation of the APU, this makes sure that sufficient fuel is available underall operation conditions.The Differential Pressure RegulationValve permits the excessive fuel, which ismore than the limit, to return to the inlet of the FCU inlet fuelfilter. To controlthe fuel flow, the regulation valve compares the fuel pressure upstream anddownstream of the Torque Motor MeteringValve. It keeps the pressure of thefuel which flows through the metering valve (independently from the fuelquantity) constantly at 50 5 psi.Because of the increase of the fuel pressure in the highpressure gear pump,the temperature of the fuel increases. The quantity of the warm fuel whichflows back to the inlet of the FCU inlet fuelfilter is sufficient to prevent theformation of ice in the filter and the FCU inlet.

Actuator Pressure Regulation-ValveThe Actuator Pressure RegulationValve is a springloaded regulation valve. Itcontrols the outlet pressure of the fuel which is used to power the IGV actuatorand the SCV actuator. The valve keeps the pressure at 325 25 psi, thus theactuators operate with constant force and speed.

Fuel Pump Drain-Port Air Check-ValveThe Fuel Pump DrainPort Air CheckValve is a check valve which opens at0.15 psi to permit the seal cavity to drain. The valve is installed on the drainvalve port as a backup air seal.

Ecology Drain SystemThe Ecology Drain System removes the remaining fuel from the Primary andSecondary Fuel Nozzles and Manifolds. The drain fuel is burned in thecombustion chamber.When the ECB receives a shutdown signal, it starts the overspeed test and anAPU cool down if APU bleed air was used. Then it sends a close command tothe Fuel Solenoid Valve on the outlet of the FCU.When the Fuel Solenoid Valve closes, the ECB energizes the Ecology DrainSolenoidValve. The valve opens and 2nd stage compressor discharge air(PCD2), which is stored in the Ecology Drain Accumulator, flows to thespring-loaded Primary and Secondary Drain Valve. This will permit the PCD2air to flow through the fuel manifolds and Fuel Nozzles into the combustionchamber. Thus the drain air removes the remaining fuel from the manifolds andatomizers.The check valve at the inlet prevents that drain air flows back to thecompressor when the pressure there decreases during the shutdown. Thecheck valve at the outlet prevents that fuel or hot gas from the combustionchamber to flows the accumulator.


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QUANHighLight

QUANHighLight

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A334-200/300GTCP 331350C

4930

PRIMARYMANIFOLD

SECONDARYMANIFOLD

FUEL CONTROL UNIT

IGVACTUATOR

SCVACTUATOR


M

SFUELFLOWMETER


PRIMARYDRAINVALVE

SECONDARYDRAINVALVE

FUELSOLENOIDVALVE

FUELMETERINGVALVE

PRESSURIZINGVALVE

FCU INLETFILTER

FUEL LP-SWITCH

HPFILTER

S

ECOLOGYDRAINSOLENOIDFUEL TEMP

SENSORFUEL PUMP DRAIN PORTAIR CHECK VALVE

dP-REG

ACT-REG

ECB

ACCUMULATOR


Page 67Figure 35 Fuel Control and Distribution System



4917 POWER PLANT DRAIN SYSTEM4916 AIR INTAKE SYSTEM4990 OIL4991 OIL STORAGE AND DISTRIBUTION4993 OIL INDICATING4994 LOP AND HOT WARNING4996 APU OIL HEATING4930 ENGINE FUEL AND CONTROL4934 APU FUEL LP WARNING4950 AIR4951 BLEED AND SURGE AIR4952 ACCESSORY COOLING4970 INDICATING4971 POWER INDICATING4972 TEMPERATURE INDICATING4973 ANALYZERS

AUXILIARY POWER UNITAPU FUEL LOW PRESSURE WARNING

A334-200/300GTCP 331350C

4934

4934 APU FUEL LP WARNINGLOW PRESSURE FUEL WARNING DESCRIPTION

GeneralThe Low Fuel PressureSwitch is installed on the Fuel Pump Inlet.

MonitoringThe aircraft APU Fuel PumpSystem supplies fuel to the inlet of the APU FuelControl Unit. A Fuel LowPressure Switch, installed at the inlet of the FCU,monitors the pressure of the APU fuel supply at the inlet port.If a fuel lowpressure occurs, the pressure switch transmits this information,via the ECB, to the EIS to generate a related warning message.


Page 68


A334-200/300GTCP 331350C

4934

APU GEN62

115400

%VHZ

BLEED35 PSI

FUEL LO PR

FLAP OPEN

AVAIL

APU

0

10N%

100

3

5 7 11

600

EGT C

FUEL LOWPRESSURESWITCH

FUELCONTROLUNIT


Page 69Figure 36 Low Pressure Fuel Warning


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4934

LOW PRESSURE FUEL WARNING OPERATION

GeneralThe APU Fuel LowPressure Warning System shows a warning on theEIS (Electronic Instrument System) SD (System Display) when the fuel at theFCU (Fuel Control Unit) has a low pressure. This is controlled from theFuelLow Pressure Switch. The ECB and the FCMC (Fuel Control andMonitoring Computer) monitor the signals from the FuelLow Pressure Switch.If a low fuel pressure occurs an ARINC bus transmits the signal from the theECB to the EIS.

Power SupplyWhen the Fuel LowPressure Switch is closed it supplies a ground signal tothe FCMC and the ECB. The ECB supplies through an 429 ARINC bus a lowfuel pressure signal to the EIS. If the fuel low pressure signal is not availablethe switch supplies a 28 V DC signal to the FCMC and the ECB.

Operation and IndicatingWhen the APU fuel pressure increase to 19.5 8.7 psi the FuelLow PressureSwitch opens and transfers a signal to the ECB. The ECB transmits the signalto EIS, this removes the indication FUEL LO PR from the EIS SD. The ECBalso stops the signal to the aft fuel feedpump.


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A334-200/300GTCP 331350C

4934

REG

28VDC

309PP1KD

MAIN SUPPLY

2KD

APU CTL

4KD APUMAIN RELAY

2LP3ANN LT

TRANSFORMER


ARINC BUSSES

5000VE

1LP3

ELECTRONICCONTROLBOX [59KD]

EIS

CMS

LOW FUEL PRESSURESWITCH [59KF17]APU FUELPUMP SYSTEMVENT ANDDRAIN VALVE FUEL CONTROL

UNIT [59KF19]

FCMC

FAULTON/R

MASTER SWITCH215VU


Page 71Figure 37 LP Fuel Warning Schematic



4916 AIR INTAKE SYSTEM4990 OIL4991 OIL STORAGE AND DISTRIBUTION4993 OIL INDICATING4994 LOP AND HOT WARNING4996 APU OIL HEATING4930 ENGINE FUEL AND CONTROL4934 APU FUEL LP WARNING4950 AIR4951 BLEED AND SURGE AIR4952 ACCESSORY COOLING4970 INDICATING4971 POWER INDICATING4972 TEMPERATURE INDICATING4973 ANALYZERS4940 IGNITION AND STARTING

AUXILIARY POWER UNITAIR

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4950 AIRINTRODUCTION

Bleed and Surge-Air SystemThe Bleed and SurgeAir System controls the supply of the APU bleed air tothe pneumatic system of the aircraft and prevents a load compressor surgeThe Bleed-Air System delivers compressed air from the APU Load Compressorfor: MES (Main Engine Start) Air Conditioning

The APU bleed air system includes a Bleed Valve, a flow regulation by meansof Inlet Guide Vanes and surge protection by means of a SCV (Surge ControlValve).The Electronic Control Box ensures control and monitoring of thesecomponents. The bleed and surgeair system controls the supply of the APUbleed air to the pneumatic system of the aircraft and prevents a loadcompressor surge

Accessory Cooling SystemAn Accessory Cooling System supplies cooling air to the APU Oil Cooler and tothe APU compartment. This is achieved by a Fan which supplies ambient airinto the APU compartment. An Accessory Cooling Valve determines theamount of compartment cooling air.The system operates independently of the APU Load Compressor and theBleed and Surgeair system.


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AUXILIARY POWER UNITAIR

A334-200/300GTCP 331350C

4950

IGVACTUATOR


BLEED CONTROLVALVE

SURGECONTROL VALVE

TO AIRCRAFTPNEUMATIC

SYSTEM

ACCESSORYCOOLINGVALVE

COOLINGFAN


Page 73

COMP

Figure 38 Air System Design



4990 OIL4991 OIL STORAGE AND DISTRIBUTION4993 OIL INDICATING4994 LOP AND HOT WARNING4996 APU OIL HEATING4930 ENGINE FUEL AND CONTROL4934 APU FUEL LP WARNING4950 AIR4951 BLEED AND SURGE AIR4952 ACCESSORY COOLING4970 INDICATING4971 POWER INDICATING4972 TEMPERATURE INDICATING4973 ANALYZERS4940 IGNITION AND STARTING4960 ENGINE CONTROLS

AUXILIARY POWER UNITBLEED AND SURGE AIR

A334-200/300GTCP 331350C

4951


4951 BLEED AND SURGE AIRDESCRIPTION

GeneralThe APU Load Compressor supplies the APU bleed air. The quantity changeswith the different bleed air demands of the aircraft pneumatic systems. VariableIGVs (Inlet Guide Vanes) which are installed at the load compressor inletcontrol the quantity of the bleed air. The IGVs are operated by an IGV-Actuatorcontrolled from the ECB. The ECB receives position feedback information froma Actuator-LVDT (Linear Variable Differential Transducer).The bleed and surge air system has the subsequent primary components: Inlet Guide Vane Actuator Bleed Flow Sensor APU Load Bleed Valve Surge Control Valve


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DIFFERENTIALPRESSURE-XDCR

IGVACT

Pt

dP

P2

TOTALPRESSURE-XDCR

S TM

ACCESSORYCOOLINGVALVE

LOAD BLEED VALVE SURGE CONTROLVALVE


LCIT

PCD-(PRESSURE COMPRESSOR DISCHARGE) STG 1

PCD2 TOECOLOGY DRAINSYSTEM

PCD1 FROM AIR/OIL SEPARATOR

BLEED FLOWSENSOR ASSY

OVBD


Page 75Figure 39 Air System Schematic


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4951


Bleed Air SystemThe bleed air flows from the scroll of the APU Load Compressor to theTeeduct which is installed on the right side of the APU. The APU Load BleedValve is installed at the forward end end of the pneumatic Teeduct on the righthand side of the APU. The Load Bleed Valve stops or permits the bleed air flowfrom the APU to the pneumatic system of the aircraft. The Load Bleed Valve isoperated pneumatically by compressor discharge air from Power CompressorStage 2.The ECB controls and monitors the APU Load Bleed Valve position. T

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