INICIAL APU APS_231107_232152

Airbus
A318/A319/A320/A321
Differences to
ATA 49
Auxiliary Power Unit
APS 3200
Line and Base Maintenance

Level 3
A318-21_49A_L3 .
Training Manual
AIRBORNE AUXILIARY POWER A319/A320/A321
APS 3200
49ï00
ATA 49 AIRBORNE AUXILIARY POWER
ATA_DOC Page 1
AIRBORNE AUXILIARY POWER GENERAL APS 3200
49ï00
49ï00 AIRBORNE AUXILIARY POWER GENERAL

APS 3200 INTRODUCTION
LEADING PARTICULARS
Main Features
S Total Equivalent Power: 400 kW (536 hp)
S Approximately Weight: 136 kg
S Specific Fuel Consumption: 0.372 kg/kWh
Operating Conditions
Supply of pneumatic and electrical power is possible simultaneously or
independently. The rated load is the gas generator power (load compressor
and gearbox power) without exceeding the gas temperature. The electrical
power always has priority in order to protect the APU against overload.
S Flight Operating Envelope
ï Pressure altitude: ï1.000 ft to 39.000 ft
ï Ambient temperature: ï70_C to +55_C
S Pneumatic and Electric Power
ï Pneumatic Power can be supplied from ï1000 ft to 20000 ft
ï Electrical Power can be supplied from ï1000 ft to 39.000ft
S Ground Operation
ï Ground Start Up Altitude up to 8000 ft
ï Ground Operation Limit up to 15000 ft
S APU Starting
ï No Limitations within Normal Flight Operating Envelope
01|49ï00|L1|B12 Page 2
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PNEUMATIC
POWER
ÎÎÎÎÎÎÎÎÎÎÎ
APU OPERATING ENVELOPE
39
ELECTRICAL
POWER 36
ELECTRICAL
POWER
PRESSURE ALTITUDE (FEET X 10.000)
30
POWER
PNEUMATIC AND/OR ELECTRICAL
ISA ISA + 35_
PRIORITY TO ELECTRICAL POWER

20
GROUND OPERATION LIMIT
ELECTRICAL POWER
15
PNEUMATIC AND
APU MAIN FEATURES
10 GROUND OPERATION
TOTAL EQUIVALENT POWER 400 kW 8
(INDEPENDENCE FROM EXTERNAL SOURCES)
SPECIFIC FUEL CONSUMPTION

0.372 kg/kWh
0
WEIGHT
136 kg (299 lb) ï1
NOISE LEVEL ï70 ï40 0 15 34 39 55

< 83 dB – AIRCRAFT DOORS
AMBIENT TEMPERATURE (_C)
< 80 dB – 20 m (65.6 ft)
PERIMETER
Figure 1 APU Operating Envelope

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General Main Components
The APU is a small turbine engine especially designed to provide electrical The main components are:
power and air when the main engines are not running. It incorporates a S The APU (Auxiliary Power Unit)
sophisticated control system which, when it receives a start signal from the
S The ECB (Electronic Control Box)
cockpit starts itself, maintains a constant speed under varying loads and
monitors its own operation continually, ready to stop if a malfunction occurs. S The aircraft systems (Pneumatic system, Electrical system, Control panels)
Under normal conditions the APU is considered as nonessential equipment. The APU is a single spool gas turbine engine which drives a load compressor
However, there are certain conditions when the APU is considered essential and an AC generator.
equipment on the MEL (Minimum Equipment List) as defined by the aircraft The ECB is an electronic controller of FADEC (Full Authority Digital Electronic
specifications. Control) type.
Purpose Component Location

The APS 3200 is designed to provide compressed air and electrical power to S The APU is installed in the tail section of the aircraft
the aircraft on the ground and during flight S The ECB is installed in the Aft cargo compartment in the fuselage.
S Electrical power supply to aircraft systems
S Compressed air supply to aircraft systems
ï ECS (Environmental Control System)
ï MES (Main Engine Start)
ï Wing Anti—icing
The APU can perform non—routine duties
S MMEL (Master Minimum Equipment List)
S ETOPS (Extended Twin Engine Operations)
The APU is then used as ”essential equipment” to provide electrical power
when one main engine is inoperative.
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ECB
AIRCRAFT TAIL CONE
AUXILIARY POWER UNIT (APU)
Figure 2 APU Presentation

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APU SYSTEMS INTRODUCTION

Power Plant (Ref. 49ï10ï00) Air (Ref. 49ï50ï00)
The power plant is installed in the rear fuselage aft of the passenger The engine is equipped to provide 2 separate air sources:
compartment. It occupies the tailcone, the rearmost portion of the fuselage. S pneumatic power (bleed air) for MES (Main Engine Start) and the ECS
The tailcone has been fitted with a fireproof compartment to house the APU. (Environmental Control System),
Peripheral systems are installed both in the APU compartment as well as to the
S cooling air for ventilation of the APU compartment and cooling of the APU
front and rear of it. Doors permit access to all components of the power plant.
lubrication system.
Engine (Ref. 49ï20ï00)
Engine Controls (Ref. 49ï60ï00)
The engine supplies:
In order to start, control its performance and to shut off the auxiliary power
S pneumatic power, system, manual and automatic controls are provided.
S electrical power, and Manual control of the APU is possible through the crew interfaces in the
S cooling air. cockpit. Automatic control is accomplished through the ECB.
To fulfill these requirements, the engine consists essentially of a power section
Indicating (Ref. 49ï70ï00)
to generate shaft power. A load compressor is flanged to this shaft to generate
pneumatic power. Subject shaft also drives a gearbox. A generator is attached The ECB monitors the operation of the auxiliary power system. It transmits
to this gearbox to generate electrical power. A fan to provide cooling air is also operation information to the A/C indicating and recording systems ECAM,
attached to the gearbox. CFDS and AIDS. It also records system faults in its internal memory. Display of
subject data is in the cockpit on the CFDS monitor.
Engine Fuel and Control (Ref. 49ï30ï00)
Exhaust (Ref. 49ï80ï00)
The APU system receives fuel from the A/C APU fuel supply system (Ref.
28ï22ï00). Incoming fuel is metered by the FCU (Fuel Control Unit) and The APU exhaust system serves to duct the engine exhaust overboard. Its
delivered to the FDDVA (Flow Divider and Drain Valve Assembly). From there secondary purpose is to reduce the exhaust noise level. In order to minimize
it is routed via 2 fuel manifolds to the fuel nozzles, located in the combustion aerodynamic losses during APU operation, the duct is designed sufficiently
chamber. large in diameter. Also, exhaust discharge takes place at the very aft end of the
A/C, where a low pressure area exists during flight. Thus it is also assured that
Ignition and Starting (Ref. 49ï40ï00) exhaust gas does not reïenter the APU air intake system
The APU is fitted with a DC starter motor (8KA), which draws its power from
the electrical system battery bus. It turns the engine to such speed that
selfïsustained engine operation becomes possible. The fuelïair mixture in the
combustion chamber is ignited by the ignition system, also fitted to the APU.
Electrical power to the ignition system is supplied through the ECB.
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BLEED CONTROL VALVE
Figure 3 APU Systems Overview

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CONTROL AND INDICATING
1 Master Switch
The MASTER SWITCH controls the power supply for the APU operation and Start P/B ”ON”
protection. The blue ON light stays on as long as the start sequence is in progress (up to
APU 95 % RPM) and illuminates when:
Master SW ”ON” (P/B pressed in)
S The Back Up Start Contactor closes when the intake flap is open
The ON light illuminates blue when:
S The Start Contactor closes
S If ground power or main generator power is used, the APU page appears on
the ECAM system display. S The Starter Motor is energized
S The APU system is powered, the ECB carries out the Power Up Test, the S at 50% RPM Starter Motor ”OFF”
air intake flap opens. S at 95% RPM the ON Light goes ”OFF”
S The APU fuel isolation and fuel low pressure valve opens. If required, the The AVAIL light comes on green 2 sec. after APU speed has reached 95 %
APU fuel pump starts running. RPM.
Master SW ”Off” (P/B released out)

3 APU Generator P/BSW (see ATA 24)
A normal shutdown sequence is initiated when the MASTER SWITCH is
released out.
S The ON light in the MASTER SWITCH goes off. 4 APU Bleed P/BSW (see ATA 36)
S If bleed air was used, the APU keeps running for a cooling period of 120
seconds maximum. 5 APU Fire Handle
At 7 % speed (N) The APU FIRE push button, when released out, causes an immediate shut
S The APU fuel isolation and fuel low pressure valve closes. down arms the fire extinguishing system and isolates the APU fuel system.
S The APU fuel pump stops.
S The air intake flap closes. 6 APU AUTO EXTINGuishing TEST SWITCH
Master SW Fault Light The test will only be done during greater maintenance checks:
The FAULT light comes on amber and the corresponding warnings are The test PB sw must be held during test. MASTER sw must be selected ON.
activated when an automatic shutdown occurs. APU FIRE warning auto extinguishing and shutdown circuits are tested.
Sequence duration is 10 sec. The OK light comes on to indicate a successful
test.
2 Start Pushbutton
NOTE: If APU is in operation, the APU shuts down.
The START push button initiates the APU start sequence.
7 RESET SWITCH
When pressed, the test circuit is resetted.
It has to be done after every AUTO EXTINGuishing TEST.
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20VU
35VU
3
30VU
50VU
4
26VU
1
Figure 4 APU Control Panels

01|49ï00|L1|B12 Page 9
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ECAM APU Page
APU parameters are displayed on the ECAM APU page. The APU generator
parameters are duplicated on the ECAM ELEC page and the APU pneumatic
parameters are duplicated on the ECAM BLEED page.
External Controls
In case of an APU FIRE warning on the ground, a loud horn will sound in the
nose wheel well to tell ground personnel. Associated with the horn, a red APU
FIRE light will come on, on the external power control panel on the lower
fuselage. It is possible to do an EMERGENCY shut down of the APU from this
panel by lifting the guard and pushing the APU SHUT OFF P/BSW.
8 APU SHUT OFF PUSH BUTTON

An APU emergency shutdown can be performed using the APU SHUTOFF
push button located on the external power control panel, next to the nose
landing gear, within the EXTERNAL POWER CONNECTOR access panel.
9 APU FIRE LIGHT

The APU FIRE red light comes on when a fire is detected on ground. Red light
illumination is accompanied by the ground horn.
Figure 5 APU ECAM SYSTEM DISPLAY
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EXTERNAL POWER CONTROL PANEL (108VU)
121VU
Figure 6 APU External Controls & Indicating

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SAFETY PRECAUTIONS
General
When you work on A/C, make sure that you obey all the Aircraft Maintenance
Manual (AMM) safety procedures. This will prevent injury to persons and/or
damage to the A/C.
S Make sure that you use the correct personal protection when you work on
the APU, as fuel and oil are poisonous.
S Do not touch the APU until it is sufficiently cool.
S If you operate the APU with the APU access doors open or removed, make
sure that you have the correct fire fighting equipment available.
S The onboard APU fire extinguishing system is not sufficient when these
doors are not closed.
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Figure 7 Safety Precautions

01|49ï00|L1|B12 Page 13
AIRBORNE UXILIARY POWER A319/A320/A321
GENERAL APS 3200
49ï00
OPERATING LIMITATIONS
02|49ï00|L3 Page 14
AIRBORNE UXILIARY POWER A319/A320/A321
GENERAL APS 3200
49ï00
OPERATING ENVELOPE STARTING TIME

INLET AIR TEMPERATURE PRESSURE ALTITUDE: FROM 0 TO GOVERNED
MAX ALLOWABLE: 55_C (131_F) -300 m + 11900 m (-1000 ft + 39000 ft) SPEED:
AMBIENT TEMPERATURE: LESS THAN 90 SECONDS
-70_C + 55_C (-94_F + 131_F)
APU ROTATION SPEED ELECTRICAL LIMITATION

NORMAL OPERATION (100%): 49300 RPM NOMINAL OUTPUT POWER:
UNDERSPEED SHUTDOWN: < 95 % 90kVA
OVERSPEED SHUTDOWN: > 105 %
OVERSPEED SHUTDOWN BACK-UP: > 107 %
OIL LEVEL
MAX OIL LEVEL:
3.8 LITERS (1 US G)
MIN OIL LEVEL:
EXHAUST GAS TEMPERATURE 2.6 LITERS (0.68 US G)
MAX CONTINUOUS:
557_C
OVERTEMPERATURE SHUTDOWN: OIL PRESSURE
670_ TO 760_C
NORMAL OPERATION:
(DEPENDING ON OUTSIDE CONDITIONS)
345 – 414 kPa (50 – 60 PSIG)
LOW OIL PRESSURE SHUTDOWN:
AIR BLEED 241 kPa (35 PSIG)
MIN FLOW: 1.16 kg/s (2.55 lb/s)
MIN. PRESSURE: 289.6 kPa (42 PS/G)
OIL CONSUMPTION
OIL TEMPERATURE
MAX OIL CONSUMPTION:
4 cc/h (0.009 PPH) MAX OIL TEMPERATURE:135_C
(HIGH OIL TEMP SHUTDOWN)
AC GENERATOR MAX OIL TEMPERATURE: 185_C
(GEN HIGH OIL TEMP SHUTDOWN)
NOTE: PROTECTIVE SHUTDOWN CONDITIONS MAY DEPEND ON ETOPS STATUS
Figure 8 Operating Limitations

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POWER PLANT APS 3200
49ï11
49ï11 POWER PLANT

POWER PLANT INTRODUCTION
Power Plant Installation
The APU power plant is installed in a fireproof compartment of the fuselage
tailcone, between FR80 and FR84. A pair of access doors on the bottom of the
tailcone opens outwards to permit the APU to be lifted and lowered.
01|ï11|Install|L1 Page 16
49ï11
EQIPM COMP APU COMPARTMENT MUFFLER

COMPARTMENT
Z310
EXHAUST
MUFFLER
FR84
APU ACCESS DOOR

316 AR APU ACCESS DOOR
315 AL
FR80
AIR INTAKE
Figure 9 APU Installation

01|ï11|Install|L1 Page 17
49ï10
APU ACCESS DOOR DESCRIPTION

WARNING: DO NOT TOUCH THE AUXILIARY POWER UNIT UNTIL IT IS CAUTION: IN THE EVENT OF DOOR REMOVAL YOU MUST SECURE
SUFFICIENTLY COOL TO PREVENT BURNS WHEN YOU DO THE RIGHT ACCESS DOOR HOLD OPEN SPRING
THE MAINTENANCE TASK. MAKE SURE THAT THE THREE MECHANISM BY INSERTING THE RED COLORED PIP-PIN IN
QUICK RELEASE FASTENERS ON THE APU LEFT ACCESS THE LOCKING HOLE. THE PIN IS STOWED NEXT TO THIS
DOOR ARE CORRECTLY STOWED. THIS PREVENTS LOCKING HOLE.
DAMAGE TO THE SEAL ON THE APU LEFT ACCESS DOOR.
DOOR OPENING
1. In the cockpit, open the APU circuit breakers
2. Position a work stand suitable to reach the aircraft under the APU
compartment.
NOTE: The APU doors are secured by a total of seven latches, five
latches secure the left door and two latches secure the right
door. The left hand door must be opened first to gain access to STOWING
the latches for the right hand door. POSITION
3. Start by releasing the rear latch. Next, the three latches connecting the
doors together are undone. As each latch is undone, secure the latch hook
on the latch lever. Continue to release the forward and aft remaining
latches.
4. When all latches have been released, pull the door open and secure with
the door support strut. The strut is stowed at the forward end of the left
door. Release the strut pipïpin from the door, extend the telescopic strut LOCKING
and secure it to the aircraft using the pipïpin. POSITION
5. Push the door open until the strut locks in the fully extended position. This
completes the opening of the left hand door.
With the left hand door open, the two latches securing the right hand door
are now visible. The forward latch is released. Followed by the rear latch
and the door is ready to be opened.
6. Use the assist handle mounted on the air inlet duct and swing the door fully
open. The door hold open mechanism incorporates a counterbalance
spring that takes most of the door weight. The door will lock automatically
in the door open position.
7. No locking pins are necessary to secure the right hand door in the open
position. The mechanism in overcentered position holds the door open.
This completes the APU door opening procedure.
Figure 10 Locking for Door Removal
02|AccDoors OPS|L2 Page 18

49ï10
The door spring will hold the door in

a over centered position when open.
NO NEED TO PUSH
CONTROL
HANDLE
ASSIST
HANDLE
Figure 11 APU Access Door Opening

49ï10
DOOR CLOSURE
1. To close the right hand door, apply a lifting force to the door with one hand,
and at the same time, tap the orange colored release handle marked
“PUSH” in a downward, outward direction to release the overcentered
geometric lock on the door hold open mechanism. Lift the door to the
closed position, using the assist handle on the air inlet duct.
2. Secure the forward and rear latches on the right hand door.
3. The left door support strut must be stowed before closing the left door.
To release the lock on the left hand door support strut, pull down on the
knurled collar. While holding the collar down, partially close the door.
4. Hold the door with the left hand and with the right hand, release the door
support strut pipïpin from the aircraft.
5. Stow the support strut on the door.
6. Lose the left door.
7. Secure the forward latch.
8. Ensure that the latch release lever is flush with the latch.
9. Secure the rear latch.
10.Secure the three latches holding the left and right doors together. Repeat
the closing procedure for the remaining latches.
SHOOT BOLTS
11.Carry out a final visual inspection to ensure that all latches are secure.
This completes the APU access door closing procedure.
12.Finally, reset the APU circuit breakers in the cockpit. QUICK
RELEASE
FASTENERS
CONTROL HANDLE
Figure 12 Access Door Latches

49ï10
ASSIST
HANDLE
Figure 13 APU Access Door Closing
49ï11
APU COMPONENT LOCATION (APU LEFT SIDE)

The following components are mentioned in the following figure:
The APU air intake which is connected to the aircraft air intake system. The oil cooler which transfers the heat of the lubricating oil to the cooling
The APU air intake has a screen to protect the APU internal components air supplied by the cooling fan assembly.
against foreign object damage.
The APU exhaust system which guide the burnt gas to the aircraft
The compartment cooling valve which is installed on the cooling fan exhaust pipe. The exhaust diffuser is located at the rear of the
assembly. powersection.
The cooling fan assembly located at the top of the gearbox front face. APU fuel flow divide
The starter motor which drives the APU rotating assembly during De-oiling valve
starting. The starter motor is located on the front face of the gear box, at
the left of the AC generator. Serial number encoder
The fuel control unit which supplies and meters fuel to the APU. It mainly
includes fuel pumps, a fuel filter, a servovalve and a 3 way solenoid
valve. The fuel control unit is located on the gearbox front face below
the starter motor.
The load compressor casing which houses the loadcompressor, the

scroll and the inlet guide vanes.
The air inlet plenum which ensures the supply of air to the compressors.
The air inlet plenum is located between the loadcompressor and the
power section.
The ignition exciter which supplies high energy to the igniter plugs.
The ignition exciter is mounted on the lower part of the air inlet plenum.
03|Comp LOC|L2 Page 22

49ï11
6 LOAD COMPRESSOR
2 COMPARTMENT CASING APU EXHAUST
COOLING VALVE 10 PIPE
3 COOLING FAN
ASSEMBLY
(with integrated PMG)
APU FLOW
11 DIVIDER
4 STARTER
MOTOR
9 OIL COOLER
7 AIR INLET
PLENUM
IGNITION
8 EXITER
5 FUEL CONTROL DE - OILING APU AIR 13

UNIT
12 VALVE 1
INTAKE SERIAL NUMBER
ENCODER
Figure 14 APU Components (Left Side)
49ï11
COMPONENT LOCATION (APU RIGHT SIDE)

The following components can be identified:
The gearbox which provides the drive for the AC generator and the Load compressor discharge pressure sensors
accessories required for APU operation. The gearbox also forms the oil
sump of the oil system Oil level sensor
The AC generator which transforms the mechanical power into electrical

Generator scavenge filter DP switch
power used by the aircraft systems
The cooling fan assembly which provides air circulation for the oil cooler RPM speed sensor (2)
and for the ventilation of the engine compartment. The cooling fan
assembly is located at the top of the gearbox front face Low oil pressure switch
The APU drain collector which collects the various drainage and leaks. Oil Temperature sensor
The collector is installed on the right side of the gearbox by means of 2
struts
The air bleed system which includes a servo valve, an actuator and a
bleed control valve
The inlet guide vane system which includes a servo valve, an actuator,
the inlet guide vanes and their control mechanism
The combustor casing which houses the combustion chamber and the
turbine wheels
Main and pilot fuel injection system installed at the rear of the combustor
casing
Inlet air pressure and temperature sensor
Load compressor discharge temperature sensor

49ï11
COOLING FAN
7 COMBUSTOR CASING
ASSEMBLY
MAIN AND PILOT FUEL 3
8 INJECTION SYSTEM
WITH PMG
AC GENERATOR
INLET GUIDE
2 MOUNTING PAD
6 VANE ACTUATOR
INLET AIR
9 PRESS. AND TEMP. RPM SPEED
SENSOR 14 SENSORS ( 2 )
LOW OIL
15 PRESS SW
LOAD COMPR.
10 DISCHARGE
TEMP. SENSOR
(NOT SHOWN)
13 GENERATOR SCAVENGE
LOAD COMPR. FILTER DP SWITCH
11 DISCHARGE
PRESS SENSORS 16
BLEED CONTROL
5 VALVE 1
OIL TEMP SENSOR GEARBOX
APU DRAIN 12 (REAR OF OIL SUMP) (INCLUDING OIL SUMP AND
4 COLLECTOR OIL SYSTEM MAIN COMPONENTS)
OIL LEVEL
SENSOR
Figure 15 APU Components (Right Side)

APU MOUNTS APS 3200
49ï12
49ï12 APU MOUNTS

DESCRIPTION
General
The suspension system is designed ’failïsafe’ with respect to the failure of any
one of the 7 suspension rods or their respective structure attachment bracket
or vibration isolator housing lug or clevis.
Forward Mounts
The left forward vibration isolator is supported by three suspension rods and is
thus fixed in space. The right forward vibration isolator is supported by two rods
such, that movement in the yïdirection is possible.
Aft Mount
The aft mount is designed similarly, but allowing movement in the xïdirection.
This design approach permits production and installation tolerances in the APU
as well as the suspension system to be washed out.
Vibration Isolators
The function of the vibration isolators is to mechanically isolate the APU from
the A/Cïstructure in order to minimize the twoïway transmission of vibration
and shocks.
In case of fire in the APU compartment, the design of the vibration isolator core
member and housing does not allow separation of these parts if the elastomer
component is damaged or destroyed. Although the function of the vibration
isolators will then be lost, the APU will settle only slightly.
Maintenance
The entire suspension system is classified ”ON CONDITION”.
Therefore, no regular maintenance tasks need to be carried out.
04|APU Mounts|L2 Page 26

APU MOUNTS APS 3200
49ï12
TAILCONE
STRUCTURE
VIBRATION
ISOLATOR
AFT MOUNT
RH FWD MOUNT
ATTACHMENT
BRACKET
LH FWD MOUNT
Figure 16 APU Mounts
04|APU Mounts|L2 Page 27
AIR INTAKE SYSTEM APS 3200
49ï16
49ï16 AIR INTAKE SYSTEM

AIR INTAKE SYSTEM DESCRIPTION
General
The air intake system supplies ambient air to the APU (Auxiliary Power Unit)
plenum chamber. The system includes:
S a fixed diverter unit,
S an air intake housing with an inlet flap and an actuator,
S an air intake duct with a diffuser and an elbow.
All the components in the system are made to give:
S a quiet operation,
S a low weight,
S a minimum flow resistance,
S a minimum air inlet distortion.
This permits the air intake to supply sufficient air to the APU during the certified
ground or flight operation conditions. It also permits the APU to operate without
any bad effects or dangerous loss of power (surge conditions).
Air Intake General
The air intake is installed to make sure that the exhaust (from the APU or main
engine) or unwanted material does not go into the system. A diverter unit is
installed in front of the air intake. Fluid gutters behind and parallel to the air
intake are also installed.
This arrangement prevents fluids, such as hydraulic fluid, glycol, fuel, oil and
water, which could possibly flow along the fuselage and enter the system.
There are no screens in the air intake, and the material does not soak up
sufficient quantities of flammable fluids to become dangerous.
01|ï16|AirIntake|L2 Page 28
49ï16
STA3730/FR80 FIREWALLS
Z310 FRONT
FIREWALL
DIVERTER
FRONT
FIREWALL STA3895/FR84
B STA3729/FR80 FLEXIBLE SEAL
GUIDE VANS
CUT OUT PARTLY
DIFFUSER
SEALED WITH FLEXIBLE
AND ELBOW
SEAL FIREWALL RH
AIR INTAKE APU ACCESS DOORS
STA3666/FR78 STA3730/FR80
LOUVER LH STA3613/FR76 AIR INTAKE DIFFUSER
STA3666/FR78
MANUAL OVERRIDE DEVICE
AIR INTAKE
FLAP ACTUATOR
AIR INTAKE
SPECIAL ELBOW
FLAT SEAL
AIR INTAKE DUCT

ACCESS DOOR RH SUPPORTS
REAR FIREWALL FLEXIBLE SEAL (ON RIGHT ACCESS DOOR)
316AR
CUT OUT SEALED WITH DIVERTER B
FLEXIBLE SEAL INTAKE NOSE
AIR INTAKE NOSE
AIR INTAKE FIXED AIR INTAKE

ON ACCESS DOOR STA38985/FR84
B AIR INTAKE FLAP
OPEN
AIR INTAKE FLAP
NOTE: LH ACCESS DOOR 315AL NOT CLOSED
SHOWN FOR CLARITY
INTAKE FLAP FLUID GUTTERS
Figure 17 Air Intake Installation
01|ï16|AirIntake|L2 Page 29
49ï16
AIR INTAKE FLAP ACTUATOR OPERATION

Air Intake Flap Open APU EMERGENCY STOP Ground Signal
To open the air intake flap the 28 V DC busbar 301PP must be energized. The 2. When the ECB 59KD receives an APU EMERGENCY STOP ground signal
circuit breakers ECB SPLY 1KD and APU CTL 2KD must be closed. for 50ms:
The MASTER SW must be set to the ON position. ï the ECB 59KD shuts down the APU immediately. When the APU speed
When the above operations are complete, the subsequent sequence occurs: has decreased to 7 %, this sequence occurs:
S the blue annunciator ON light in the MASTER SW comes on, ï the ECB 59KD transmits a ”flap close” command signal to the air intake
flap actuator,
S the APU MAIN relay 4KD is energized,
ï the air intake flap actuator operates to close the air intake flap. After the
S the busbar 301PP supplies 28 V DC to the ECB 59KD, through the APU
air intake flap has closed:
MAIN relay 4 KD,
ï the (close) position switch of the air intake flap actuator transmits a ”flap
S the ECB 59KD transmits a ” flap open ” command signal to the air intake
closed” signal to the ECB 59KD (Ref. 49ï61ï00).
flap actuator,
After the MASTER SW 14KD is set to OFF:
S the air intake flap actuator operates to open the air intake flap. When the air
intake flap actuator reaches its fully open position, a ”flap open” signal is ï the APU MAIN relay 4KD is deïenergized,
transmitted to the ECB 59KD. ï the ECB 59 KD 28 V DC supply is disconnected through the APU MAIN
The air intake flap is fully open in approximately 20 s. RELAY 4KD.
Air Intake Flap Close Air Intake Flap Not Fully Open (Class 1 Fault)
1. Normal APU S/D (Shutdown) 3. When the ECB 59KD BITE (BuildïIn Test Equipment) completes the PUT
(Power Up Test) but does not receive an inlet door open signal within
When the MASTER SW 14KD is set MANUALLY to OFF position, these
30seconds:
steps occur:
ï the ECB 59KD inhibits the APU start,
ï the APU continues to run for up to 120 s in a coolïdown cycle if the APU
BLEED SW was in ON position. This coolïdown period is set in the ï the ECB 59KD transmits a ’flap close’ command signal to the air intake
workshop. flap actuator,
When the APU speed has decreased below 7 %, this sequence occurs: ï the air intake flap actuator operates to close the air intake flap. When the
air intake flap actuator reaches its fully closed position:
ï the ECB 59KD supplies a ”flap close” command signal to the air intake
flap actuator, ï the (close) position switch of the air intake flap actuator transmits a ”flap
closed” signal to the ECB (Ref. 49ï61ï00).
ï the air intake flap actuator operates to close the air intake flap. After the
air inlet flap actuator has closed: After the MASTER SW 14KD is set to OFF:
ï the (close) position switch of the air intake flap actuator transmits a ”flap ï the APU MAIN relay 4KD is deïenergized,
closed” signal to the ECB 59KD (Ref. 49ï61ï00), ï the ECB 59 KD 28 V DC supply is disconnected through the APU MAIN
ï the APU MAIN relay 4KD is deïenergized, relay 4KD.
ï the ECB 59KD 28 V DC supply is disconnected through the APU MAIN
RELAY 4KD. The air intake flap closes fully in approximately 20s.
02|ACT Ops|L3 Page 30

49ï16
APU CTL
2KD 61KD
NOTE: Signal switches operate 2.5mm
75KD prior operation of stroke limiting
ECB SPLY switches.
1KD 74KD Shown in flap closed position.
Flap CLOSED = Actuator extended
301PP 4KD APU

121VU MAIN RELAY
107VU
FAULT
ON
14KD
MASTER SWITCH 25VU
SIGNAL FLAP CLOSED
CLOSED
COMMAND FLAP CLOSE
ECB POWER SUPPLY CLOSING

MAIN RELAY OUTPUT (GROUND)
POWER (GROUND) BRAKE OPENING
CASE (GROUND)
COMMAND FLAP OPEN

OPEN
SIGNAL FLAP OPEN
28VDC POWER SUPPLY
SIGNAL FLAP MOVEMENT
4015KM
59KD ECB AIR INTAKE ACTUATOR (BASIC VERSION)
Figure 18 Air Intake Flap Electrical Schematic

02|ACT Ops|L3 Page 31
49ï16
AIR INTAKE COMPONENT DESCRIPTION

Air Intake Diverter
The fixed diverter increases the ramïair recovery as it reduces the lowïenergy
part of the boundary layer (during APU operation in flight). It also makes sure
that any fluids which could flow along the fuselage, do not go into the air intake.
The diverter is installed between FR76 and FR78.
AirïIntake Flap Actuator

An electrical linear actuator operates the air intake flap.
The air Intake flap actuator includes:
S a DC Motor with Brake Control
S two Travel Limit Switches
S two Position Switches (one for open and one for close position)
S a Thermal Overload Protection Device
S an Electrical Connector
S a Manual Override Device
The DC motor drives a screw jack assembly through a system of gears and
cluster gears. This extends or retracts the air intake flap.
Two travel limit switches control the length of extension and retraction of the
actuator which has a linear travel of 75 mm.
Two flap position switches are installed 3mm from the maximum extend and
retract positions of the actuator.
They send “flap open“ and “’flap closed“ signals to the ECB 59KD, which are
then displayed on the ECAM when the APU systems page is selected.
A Manual Override Device, installed on the actuator, permits the air intake flap
to be opened or closed manually on the ground with a normal tool.
This operation is done through the access door 314AR.
03|Components|L3 Page 32
49ï16
BRACKET
STA3895/FR84
MANUAL OVERRIDE
DRIVE 4015 KM
AIR INTAKE
AIR INTAKE ACTUATOR
PANEL 314AR STA3730/FR80
STA3666/FR78
DIVERTY
DIVERTER
CASE
AIR INTAKE DIVERTER
DIVERTER
PLATE
Figure 19 Air Intake Components
DRAIN SYSTEM APS 3200
49ï17
49ï17 APU DRAIN SYSTEM

APU DRAIN SYSTEM DESCRIPTION
General Air Bypass Plenum
The system (Ecological system) collects the drainage and leaks in a small drain The air bypass plenum which is installed on the lower exhaust casing section,
tank which is discharged overboard via a drain mast when the aircraft speed is provided with a drain line direct to the drain mast.
reaches about 200 kt.
Exhaust Coupling Drain
The heatshield drain and the exhaust coupling drain are mounted together and
drained directly overboard through the same drain mast. The exhaust coupling and heatshield drain are mounted together and drain
directly to the drain mast.
Fuel/Oil Pump Drain
Fuel Flow Divider
The fuel and oil pump seal drain line is routed via a collector line to the drain
tank As the pressure decreases in the fuel system (during APU shutdown), the two
valves of the flow divider close. Then, the fuel which remains in the pilot
This line drains fuel or oil leaks
injector and manifold is purged to the exhaust.
BCV (Bleed Control Valve) Actuator Drain
Oil Vent
Drain of possible leakage through the actuator shaft seal
The gearbox is vented to the exhaust through an external pipe.
Inlet Guide Vane Actuator Drain
Drain Tank
The IGV (Inlet Guide Vane) actuator drain line is routed via a collector line to
The various drain lines are connected to a drain tank (collector) which retains
the drain tank.
the liquid until the aircraft is flying.
This line drains only fuel leaks.
The bottom of the tank is connected to a suction line which is positioned so that
Front Bearing Seal Drain the tank is drained only when the pressure makes it possible. This usually
happens when the aircraft speed reaches approximately 200 kt.
Oil leak flows overboard and indicates a front bearing seal failure.
Combustor Drain
Combustion chamber drain. The lower part of the combustor casing has a drain
valve which drains unburnt fuel. The valve which is actuated by air pressure,
closes when the compressor delivery pressure becomes sufficient at about
10% Rpm.
05|ï17|DrainSystem|L3 Page 34
DRAIN SYSTEM APS 3200
49ï17
APU TAILCONE INTERFACE
FUEL
FRONT AIR
CONTROL BCV ACT. IGV ACT. PILOT FUEL EXHAUST
BEARING BY-PASS
UNIT/ SEAL SEAL MANIFOLD MUFFLER
SEAL PLENUM
OIL PUMP DRAIN DRAIN PURGE DRAIN
DRAIN DRAIN
SEAL DRAIN
(1) (2) (2) (5) (2) (2) (3)
COMBUSTOR
HOUSING
DRAIN
(2)
APU
FWD MID AFT APU DRAIN BRACKET

COUPLING
KISS SEAL
APU
COMPARTMENT
SUCTION LINE
VENT LINE
DRAIN
BOTTOM OF
TANK TAIL CONE
FUEL AND OIL PUMP DRAIN BCV

DRAIN ACTUATOR SEAL DRAIN IGV
MAST ACTUATOR SEAL DRAIN
(1) OIL/FUEL
(2) FUEL
(3) DRAIN, CLEANING FUEL FRONT BEARING
(4) IN CASE OF APU SYSTEM LEAKS SEAL DRAIN DRAIN COLLECTOR
OR SPILLAGE DURING APU
APU COMPARTMENT(3,4) SERVICING: OIL/FUEL COMBUSTOR DRAIN
DRAIN (5) OIL EXHAUST COUPLE DRAIN
Figure 20 APU Drain System
05|ï17|DrainSystem|L3 Page 35
ENGINE APS 3200
49ï20
49ï20 ENGINE
INTRODUCTION
Purpose
The APU provides compressed air and electrical power to the aircraft.
Location
The APU is installed in the aircraft tail section.
Type
The Auxiliary Power Unit is of the SSLC (Single Shaft Load Compressor) Type
Gas Turbine Engine driving a load compressor and an AC generator through a
gearbox.
Main Components
S Gearbox (with AC generator and APU accessory drive)
S Load compressor (centrifugal type provided with inlet guide vanes)
S Air inlet plenum (air intake and air distribution)
S Power section including:
ï a centrifugal compressor
ï a reverse flow combustion chamber (or combustor)
ï a two stage axial flow turbine.
Figure 21 APU Total Views
06|ï20|Sections|L1 Page 36
ENGINE APS 3200
49ï20
LOAD
COMPRESSOR POWER SECTION
CENTRIFUGAL COMBUSTION
GEARBOX COMPRESSOR CHAMBER TURBINE
GENERATOR AIR INLET PLENUM
Figure 22 APU Sections

06|ï20|Sections|L1 Page 37
ENGINE APS 3200
49ï20
APU BORESCOPE INSPECTION

Visual Inspections
APU general visual inspection
Visually inspect components for tightness, worn areas, cracks and corrosion:
S Electrical connectors and harness
S Air, oil, fuel pipes
S Units
S Engine external casings.
Borescope Inspection
The APU internal components can be inspected using a fiberscope (5 mm
diameter) Borescoope and the handcrank provision is by turning the cooling fan
at the top of the gearbox.
The components which can be inspected are:
S The load compressor impeller (all blade leading edges) inspection through
the air inlet plenum, the load compressor air intake and the drilled inlet
guide vanes
S The power section compressor impeller (all blade leading edges): inspection
through the air inlet plenum and the power section air intake
S The combustor (2 places ï 3 borescope orientations) inspection through the
left and right igniter plug boss
S The first stage turbine wheel (all blade leading edges) inspection through
the left igniter plug boss, the combustor and the first stage nozzle guide
vane
S The second stage turbine wheel (all blade trailing edges) inspection through
the thermo couple boss.
One CAUTION concerning the heat which can damage the fiberscope.
Refer to Aircraft Maintenance Manual for procedure, examination and damage
criteria.
07|Borescope|L3 Page 38
ENGINE APS 3200
49ï20
BORESCOPE INSPECTION
OF THE COMBUSTER
BORESCOPE INSPECTION OF THE
SECOND STAGE TURBINE WHEEL
(TRAILING EDGES)
BORESCOPE INSPECTION OF
THE FIRST STAGE TURBINE WHEEL
(LEADING EDGES)
BORESCOPE INSPECTION OF BORESCOPE INSPECTION OF

THE LOAD COMPRESSOR IMPELLER THE PS COMPRESSOR IMPELLER VISUAL INSPECTIONS
Figure 23 APU Borescope Inspection

07|Borescope|L3 Page 39
OIL APS 3200
49ï90
49ï90 OIL
OIL SYSTEM DESCRIPTION
Function Pressure Supply
The system is used to lubricate and cool the APU and the AC generator. The pressure pump draws the oil from the sump and delivers it under pressure.
During starting, the deïoiling valve opens and air is drawn into the pump in
Location order to reduce the load. The oil passes to the oil cooler, then to the filter which
The system components are all located on the gearbox except the oil cooler retains any particles in the oil.
which is located on the APU left side. If the filter becomes blocked, the Delta P indicator operates, and then the
byïpass valve. If the pump pressure exceeds a given value, the relief valve
Main Features
opens and returns excess oil to the inlet side of the pump.
Selfïcontained, full flow system. The system operates with the same oil types
The oil pressure is sensed by a pressure switch which detects low pressure.
as approved for the main engines.
The oil then flows to lubricate and cool:
S Max oil temperature: 135_ C (275_ F)
S the AC generator
S Max oil consumption: 4 cc/h (0.009 PPH)
S the AC generator splines
S Normal oil pressure: 345 ï 414 kPa (50 ï 60 PSIG)
S the APU splines
S Low oil pressure: 241 kPa (35 PSIG)
S the cooling fan splines
S Oil volume: 3.8 liters (1 US G) at FULL mark.
S the gearbox
Lubrication and Cooling Requirements S the front bearing
The requirements are for: S the rear bearing.
S the APU rear bearing
Scavenge Return
S the APU front bearing
After lubrication, the oil falls to the bottom of the sumps and is immediately
S the gearbox gears and bearings scavenged by two pumps:
S the AC generator S One for the power section rear bearing which returns the oil directly to the
No oil is permitted to leak into the load compressor or the air bleed system sump
Satisfactory operation is ensured in the event of prolonged windmilling in the S One for the AC generator which returns the oil to the sump through a filter.
normal and reverse direction.
NOTE: The front bearing and the gearbox are scavenged by gravity.
Oil System Operation
Venting
The main functions of the oil system are: pressure supply, scavenge return,
Oil mist in the gearbox passes through a centrifugal airïoil separator. The
venting and indicating.
gearbox is vented to the exhaust through an external pipe.
01|ï90|Oil System|L2 Page 40

OIL APS 3200
49ï90
OIL-FREE AIR DISCHARGE LINE REAR BEARING

AIR/OIL VENT LINE
LOP SWITCH
GENERATOR HOT SWITCH
SCV PUMP AC GEN
FRONT
BEARING REAR
BEARING
∆P SWITCH
DE-OILING
VALVE
PRESSURE
RELIEF VALVE
OIL LVL SENSOR
SIGHT
OIL COOLER
MAGN DRAIN PLUG GLASS ∆P SWITCH
HOT SENSOR
PRESS
PUMP
PRESSURE
FILTER
Figure 24 Oil System Schematic

OIL APS 3200
49ï90
Oil Sump Monitoring Devices
The oil sump is formed by the lower part of the gearbox. S low oil pressure switch
The gearbox has a fill tube for gravity filling, an overflow drain, a pressure fill S high oil temperature sensor
connector and a sight glass. S AC generator high oil temperature sensor
An air/oil separator is formed by one of the gears in the gearbox, and is S oil level sensor
connected to the gearbox vent.
S oil level sight glass
Oil Pump S Supply and generator scavenge oil filter impending blockage indicators
One pressure pump and two scavenge pumps are mechanically driven and are S Generator scavenge oil filter impending blockage switch
mounted on a drive pad of the gearbox. S Magnetic chip detector.
The pressure system is provided with a pressure relief valve located on the
gearbox.
Oil Filters
There is one filter on the pressure line and one on the AC generator scavenge
line.
Both filters are similar. They comprise the filter element, a byïpass valve and
an impending filter blockage indicator. They are mounted on the lower front
face of the gearbox. The scavenge filter has an impending filter blockage
switch.
Oil Cooler
The oil cooler (with an APU driven fan) cools the oil after the pressure pump.
The cooler has a byïpass valve.
DeïOiling Valve
The deïoiling valve is a solenoid valve located at the inlet of the pressure
pump. When open, the valve prevents oil flow thus reducing the load on the
pump.

OIL APS 3200
49ï90
THIS PAGE INTENTIONALLY LEFT BLANK

OIL APS 3200
49ï90
OIL SERVICING
OIL SUMP
The sump contains the oil required for the APU lubrication. It is located in the
bottom of the gearbox. The capacity of the oil sump must be able to ensure
300 operating hours without refilling at the max oil consumption rate.
An oil level sight glass is located on the lower left side of the gearbox housing,
close to the oil fill tube.
It provides a visual indication of the oil level in the sump.
When the level is at the “ADD” mark, the APU must be able to continue running
for at least 60 hours.
S Capacity at the “FULL” mark: 3.8 liters (1 USG)
S Capacity at the “ADD” mark: 2.6 liters (0.68 USG)
S Max oil consumption: 4 cc/h (0.009 PPH).
Main Components
The main components which are part of the oil sump are the following
S Fill tube
S Oil overflow boss
S Oil pressure fill port
S Airïoil separator
S Draining point and magnetic plug
S Pressure relief valve
S Oil level sensor
S Oil level sight glass.
Magnetic Chip Detector

A magnetic drain plug is located on the lower front side of the gearbox housing.
Removing the plug allows the oil drainage from the sump. The drain plug
embodies a magnetic chip detector that attracts ferrous metal particles in the
oil. The detector can be removed, inspected and installed without draining the
oil sump.
A self sealing device located inside the drain plug prevents the oil drainage
when the detector is removed.
02|Servicing|L2 Page 44
OIL APS 3200
49ï90
GEARBOX AIR-OIL SEPARATOR
FCU DRIVE
SHAFT
DE OILING VALVE
FILL TUBE
OIL SYSTEM
PRESS PUMP &
SCAVENGE SPEED SENSOR (2)
PUMPS OIL OVERFLOW OIL LEVEL SIGHT GLASS
BOSS FULL MARK:
3.8 LITERS (1 USG)
OIL PRESSURE ADD MARK:
FILL PORT 2.6 LITERS (0.68 USG)
OIL
LEVEL
SENSOR HIGH OIL
TEMP. SENSOR
PRESSURE
DRAINING POINT RELIEF VALVE GEARBOX SUMP
AND MAGNETIC PLUG OIL LEVEL
MAGNETIC CHIP DETECTOR OIL LEVEL SIGHT

GLASS
Figure 25 Oil Servicing
02|Servicing|L2 Page 45
OIL APS 3200
49ï90
OIL SYSTEM COMPONENT DESCRIPTION

OIL PUMP MODULE Gerotor Type Function
One pump module contains a pressure pump for the pressure supply and two The gerotor is a positive displacement pumping unit consisting of an inner and
scavenge pumps for oil return. The oil pump module is mounted on a pad on outer rotor. The inner rotor has one less tooth than the outer, and has its
the gearbox front face. centerline positioned at a fixed eccentricity from the centerline of the outer
element. The inner element is driven by one pinion of the gearbox.
Pressure Pump (Vane Type)
S Pressure: 380 ï 450 kPa (55ï65 PSID) Vane Type Function
S Flow: 2160 l/h (570 GPH) The vane type pump is a pumping unit consisting of a slotted inner rotor
equipped with vanes and a precision ground cam profile plus housing body.
Pressure relief valve setting: 450ï52OkPa (65ï75 PSID)
Pressure Relief Valve Operation
AC Generator Scavenge Pump (Vane Type)
The oil pressure relief valve is a non adjustable, spring loaded relief valve.
S Flow 2160 l/h (570 GPH)
It opens when the pump pressure exceeds 450ï520 kPa (65ï75 PSIG), thus
Rear Bearing Scavenge Pump (Gerotor Type) allowing the return of the oil to the sump.
S Flow: 160 l/h (42 GPH)
SCV PUMP AC GEN

FROM REAR TO GEN, GEAR BOX
SCV FILTER BEARING AND ALL BEARINGS
∆P SWITCH SCV PUMP

PRESSURE
ÇÇÇÇÇÇÇÇÇÇÇÇÇÇÇÇÇ
Ç ÇÇ
DE-OILING RELIEF VALVE
VALVE
∆P HOT
INDICATOR OIL COOLER SENSOR ∆P SWITCH
PRESS PUMP PRESSURE

BYPASS VALVE FILTER
Figure 26 Lubrication
OIL APS 3200
49ï90
PUMP
PRESSURE
FUEL PUMP DRIVE
OIL PUMP
DRIVES
REAR BEARING
SCAVENGE PUMP AC GENERATOR
SCAVENGE PUMP
Figure 27 Oil Pump Description
OIL APS 3200
49ï90
OIL COOLER
Purpose Check valve operation
The oil cooler transfers the heat of the lubricating oil to the air cooling system. The check valve is an oil pressure operated valve. When the pressure in the oil
system is very low (at the beginning of the APU starting and at the end of the
Location APU shutdown sequences), the check valve closes and thus prevents possible
The oil cooler is installed on the left side of the APU. oil leaks through the rotor bearings.
In the oil system, the cooler is located between the pressure pump and the
Air flow
filter.
The air, which is taken from the plenum chamber and accelerated by the fan,
Main features flows through the oil cooler and is then vented overboard. Refer to cooling fan
S Oil cooling ability: 2160 l/h (540 GPH) for more details.
S Heat rejection capacity
S Oil cooler byïpass valve setting
ï Opening threshold: 207 kPa (30 PSID)
ï Fully open: 345 kPa (50 PSID).
Oil Cooler Design
The oil cooler is a rectangular unit which includes:
S An oil cooler housing which consists of an integrally brazed aluminium
heatïexchanger with aluminium face flanges and stainless steel backïup
flanges located on the air side
S A check valve and a byïpass valve to regulate the internal pressure and the
oil flow through the oil cooler
S A drain plug to drain the oil cooler. HOT
SENSOR PRESSURE
DE-OILING FILTER
OIL COOLER OPERATION VALVE
Normal Operation
OIL COOLER ∆P SWITCH
The oil delivered by the pressure pump flows through the aluminium cooling
tubes which are subjected externally to a “cold” air flow accelerated by a fan.
The cooled oil is then delivered to the various APU lubrication points through
the lubrication filter.
PRESS PUMP PRESSURE
Byïpass operation FILTER
When the pressure exceeds 207 kPa (30 PSID), the byïpass valve opens.
BYPASS VALVE
The oil circulation byïpasses the cooler. The oil is then delivered to the
lubrication system.
Figure 28 Oil Cooler Bypass Valve Schematic
OIL APS 3200
49ï90
BY-PASS VALVE
COOLING AIR INLET
CHECK VALVE
COOLING AIR
OUTLET
OIL OUTLET
COOLING AIR OUTLET
DRAIN PLUG OIL INLET
OIL COOLER
HOUSING
COOLING AIR CIRCULATION
Figure 29 Oil Cooler and Bypass Valve Description

OIL APS 3200
49ï90
OIL FILTER
Function Location
The function of the oil filters is to remove debris from the lubricating oil. The The lubrication filter is located on the pressure line after the oil cooler.
filters retain small pieces of matter held in the oil. There are two filters, one on The scavenge filter is located after the AC generator scavenge pump.
the pressure line, and one on the AC generator scavenge line. They are of
On the engine, both filters are installed at the bottom front face of the gearbox.
similar construction.
Main features:
Each filter consists of:
S Filter element: 20 microns
S A 20 micron disposable cartridge
S Byïpass valve setting: 345ï414 kPa (50ï60 PSID)
S An oil filter impending blockage indicator
S Impending blockage indicator: 207ï241 kPa (30ï35PSID)
S A byïpass valve.
S Delta P switch setting: 207ï241 kPa (30ï35 PSID)
NOTE: The AC generator scavenge filter is also provided with a Delta P
switch connected to the ECB (Electronic Control Box).
(Refer to oil filter operation for more details).
SCV PUMP AC GEN
GENERATOR
SCV FILTER
∆P SWITCH
HOT
SENSOR LUBRICATION
DE-OILING FILTER
VALVE
∆P SWITCH
∆P
INDICATOR OIL COOLER
PRESS PUMP PRESSURE

FILTER
BYPASS VALVE
Figure 30 Oil Filter Schematic
OIL APS 3200
49ï90
∆P SWITCH
LUBRICATION
AC GENERATOR
FILTER
SCAVENGE FILTER
OIL OUTLET OIL INLET

FILTER
BY-PASS VALVE IMPENDING
GEARBOX BOTTOM BLOCKAGE
(FRONT FACE) ∆P INDICATOR
BLOCKAGE
INDICATORS
TO ECB
FILTERING
CARTRIDGE
∆P SWITCH
(ON SCAVENGE FILTER)
Figure 31 Oil Filter Description

OIL APS 3200
49ï90
DEïOILING VALVE
Purpose
The deïoiling valve reduces the pressure pump load during starting, especially
during cold start conditions when the oil becomes very thick.
Location
On the APU the valve is located on the left side of the gearbox.
In the oil system: the valve is located at the inlet of the pressure pump.
Main features:
S Solenoid valve operated by the ECB (as a function of a given rotation
speed)
S Solenoid valve energized open.
Description
The deïoiling valve is a solenoid operated valve directly controlled by the ECB.
The valve includes :
S an air inlet port
S an oil inlet port
S an outlet port.
Operation
During engine starting, the deïoiling valve is energized open by the ECB. This
prevents oil flow through the pressure pump and reduces the load on this
pump.
Above 55 % of the APU rotation speed, the ECB deenergizes the deïoiling
valve which closes. Then, the oil pump produces pressure for the circuit.
During engine shutïdown, the deïoiling valve is energized open by the ECB
when APU stop is selected and speed decreases below 95 %. The valve then
supplies air to the oil pressure pump. This is to prevent coking of the oil
remaining in the bearing chambers.
OIL APS 3200
49ï90
DE-OILING VALVE
DE-OILING
VALVE
GEARBOX LEFT SIDE OIL SUMP

TO OIL COOLER
(55% ,95% ) PRESS PUMP
(VALVE ENERGIZED OPEN

ECB DURING
STARTING AND SHUTDOWN)
AIR TO OIL PUMP
OIL FROM SUMP

Figure 32 DeïOiling Valve
OIL APS 3200
49ï90
LOW OIL PRESSURE SWITCH
Purpose
The LOP (Low Oil Pressure) switch senses the pressure downstream of the
filter. The LOP switch initiates automatic APU shutdown when the oil pressure
is too low.
Location
The LOP switch is located in the AC generator pressure line of the oil system
and is mounted on the air intake plenum.
Main Features
S LOP switch setting: 241 kPa (35 PSID)
S Output signal to ECB: ground signal.
Interfaces
S The ECB
S The APU oil system.
Operation
The LOP switch mainly consists of a switch contact which is normally open.
A decreasing oil pressure below 241 kPa (35 PSID) downstream of the filter
causes the contact to close.
The LOP switch then puts out a ground signal to the ECB which can initiate the
automatic APU shut down.
OIL APS 3200
49ï90
ECB
LOP SWITCH
LOW OIL PRESSURE
CONTACT
SWITCH
APU RIGHT SIDE
LOP SWITCH 3 WAY

OIL SOLENOID VALVE
PRESSURE (IN FCU)
GENERATOR
PRESSURE (FOR APU SHUTDOWN
LINE IF REQUIRED)
FROM
AC GEN LUBRICATION TO AC
FILTER GENERATOR
LOP SWITCH OPERATION

Figure 33 Low Oil Press. Switch Description
OIL APS 3200
49ï90
HIGH OIL TEMPERATURE SENSOR
Purpose Interfaces
The HOT (High Oil Temperature) sensor measures the temperature of the oil S The ECB
at the outlet of the oil cooler. When the oil temperature is too high, the HOT S The APU oil system.
sensor initiates automatic APU shut down.
Operation
Location
The HOT sensor is a RTD (Resistance Temperature Detector) supplied by the
On the APU, the HOT sensor is installed on the lower rear face of the gearbox. ECB with a constant current of 1 mA. The resistance varies with the oil
In the oil system, the HOT sensor is located on the pressure line downstream temperature and modifies the sensor output voltage.
of the oil cooler. When the oil temperature reaches a limit value of approximately 135_C
(275_F), the ECB can initiate the automatic APU shutdown.
Main Features
S HOT sensor setting: 135_C (275_F) NOTE: The AC generator has also a high oil temperature sensor which
causes the APU to shutdown when an excessive temperature is
S Sensor input signal (from ECB): 1 mA
detected.
S Sensor output signal (to ECB): variable output voltage.
HOT
SENSOR
LUBRICATION
DE-OILING FILTER
VALVE
OIL COOLER ∆P SWITCH
PRESS PUMP PRESSURE

FILTER
BYPASS VALVE
Figure 34 Figure Text

OIL APS 3200
49ï90
ECB
3WAY
RESISTANCE 1 mA SOLENOID VALVE
TEMPERATURE (IN FCU)
DEVICE (FOR APU SHUTDOWN
IF REQUIRED)
HOT SENSOR
FROM TO
OIL LUBRICATION
COOLER FILTER
GEARBOX LEFT SIDE HOT SENSOR OPERATION
Figure 35 High Oil Temp. Sensor

OIL APS 3200
49ï90
AC GENERATOR SCAVENGE FILTER DELTA-P SWITCH Interfaces
S The APU oil system
Purpose
S The ECB (for the Delta P switch).
The oil filter impending blockage indicators and the differential pressure switch
(Delta P switch) indicates the preïblockage situation of the filter. Operation
Location Differential pressure switch (Delta P switch)
The oil filter impending blockage indicators and the Delta P switch are located When the cartridge of the scavenge filter becomes dirty, the difference of
on the gearbox lower front face close to the oil filters. pressure across the cartridge increases. For a Delta P higher than
207ï241 kPa (30ï35 PSID), the Delta P switch sends an electrical ground
Main Features signal to the ECB.
S Delta P switch: 207ï241 kPa (30ï35 PSID).
IMPENDING BLOCKAGE
* INDICATORS
SCV PUMP AC GEN (207ï241 kPa/30ï35 PSID)
GENERATOR
SCV FILTER
∆P SWITCH
LUBRICATION
DE-OILING FILTER
VALVE
∆P SWITCH
∆P
OIL COOLER
INDICATOR
*
*
PRESS PUMP PRESSURE
FILTER
BYPASS VALVE
Figure 36 Figure Text

OIL APS 3200
49ï90
LUBRICATION AC GENERATOR OIL INLET

OIL FILTER
FILTER SCAVENGE FILTER
∆P SWITCH
ÇÇ
ÇÇ IMPENDING
BLOCKAGE
INDICATOR
AND
ECB ∆P SWITCH
OIL OUTLET
IMPENDING BLOCKAGE
INDICATORS
(207ï241 kPa/30ï35 PSID)
Figure 37 Generator Scavenge Filter Delta P Switch

OIL APS 3200
49ï90
GENERATOR HIGH OIL TEMPERATURE SENSOR
The Generator High Oil Temperature Sensor senses the oil temperature in the
generator.
S A signal will be send to the APU ECB when the temp. exceeds 185_C. This
leads to an APU Auto shutdown.
S The Sensor is located inside of the generator
OIL APS 3200
49ï90
TO A/C AC W (FROM APU

ELECTRICAL GENERATOR POWER SECTION)
NETWORK 3O
LUBRICATION AND COOLING OIL

(FROM APU OIL SYSTEM)
POWER FEEDER ECB

(4 CABLES)
3WAY
GENERATOR 1 mA SOLENOID VALVE
ELECTRICAL HIGH OIL TEMP. (IN FCU)
CONNECTOR SENSOR (FOR APU SHUTDOWN
(TO GCU AND ECB) (INTERNAL OF IF REQUIRED)
GENERATOR)
GENERATOR
OIL
AC GENERATOR HOT SENSOR OPERATION
Figure 38 Generator High Oil Temp. Sensor
OIL APS 3200
49ï90
OIL LEVEL SENSOR
The oil level sensor measures the quantity of oil in the gearbox sump.
When the oil level is too low, the sensor provides a flight deck warning of low
oil quantity.
The oil level sensor is located on the right side of the gearbox.
Main features
S Sensor input signal (from ECB): 75 mA
S Sensor output signal (to ECB): variable output voltage.
Interfaces
S The ECB
S The APU oil system
Operation
The oil level sensor is a RTD (Resistance Temperature Detector) supplied by
the ECB with a constant current of 75 mA.
The resistance varies with the oil level and modifies the sensor output voltage
checked by the ECB.
At power up, the oil level is checked over a period of 8 seconds and is
determined OK or LOW by the ECB.
If the oil level is too low (less than 2,6 liter), the ECB sends a warning signal to
the aircraft control panel (ECAM lower display unit). and CFDS.
OIL APS 3200
49ï90
75 mA
ECB
GEARBOX SUMP
OIL
OIL LEVEL LOW OIL LEVEL
SENSOR SENSOR
GEARBOX FRONT FACE RESISTANCE
TEMPERATURE
DETECTOR
Figure 39 Oil Level Sensor

OIL APS 3200
49ï90
AIRïOIL SEPARATOR
Purpose
The airïoil separator separates the oil from the air.
Location
The airïoil separator is located in the upper part of the gearbox.
The separator is installed on the intermediate idler gear driving the oil cooling
fan.
Description
The airïoil separator consists of several vanes mounted on the intermediate
gear driving the cooling fan.
The pinion is integral with a hollow shaft with radial drillings. This shaft is
supported by two roller bearings, the sealing of the rear one being made by a
lip seal. The rear end of the hollow shaft vents into a passage in the gearbox
casing in order to expel to the exhaust the deïoiled air
Operation
During engine running, the air oil mist created by the lubrication of the gears
and bearings is separated by the rotating action of the air oil separator located
inside the gearbox.
The deïoiled air is then vented to the exhaust through an external pipe.
The oil returns to the sump by gravity.
OIL APS 3200
49ï90
DE-OILED AIR VENTING

(TO APU EXHAUST)
OIL MIST
INTERMEDIATE
IDLER GEAR AIR-OIL
SEPARATOR
TO EXHAUST
AIR-OIL HOLLOW (THROUGH AN
SEPARATOR SHAFT EXTERNAL PIPE)
OIL MIST DE-OILED AIR

(FROM LUBRICATION) (TO APU EXHAUST)
LIP SEAL
ROLLER OIL RETURN

BEARINGS TO SUMP
(BY GRAVITY)
OIL RETURN TO SUMP
(BY GRAVITY)
Figure 40 AirïOil Separator

AIRBORNE AUXILIARY POWER A321ï132
ENGINE FUEL AND CONTROL APS 3200
49ï30
49ï30 ENGINE FUEL AND CONTROL

APU FUEL FEED SYSTEM DESCRIPTION
System Layout
a vent APU fuel line switch 8QC,
The Auxiliary Power Unit fuel feed system is connected to the aircraft
mainïengine fuel feed system and supplies fuel to the APU fuel system.
The APU fuel feed system includes: an APU inlet fuel low pressure switch 5030QM,
an APU fuel feed pump 4QC and canister 9QM, a fuel drain and vent valve 5040QM,
an APU fuel pressure switch 7QC, a fuel feed line with a vented shroud, witch connects to a drain mast
an actuator fuel LP valve 3QF and APU fuel low pressure isolation valve
14QM,
(FROM ECB) AND

MASTER SW P/B NO SHUT
ON AND DOWN
LOW PRESSURE
OPENING
VENT FUEL LINE SIGNAL
P/B
RUNNING
SIGNAL ECB
APU INLET
FUEL PRESSURE
FEED SWITCH/
VALVE SENSOR
PRESSURE M M
SWITCH/ FUEL
SENSOR CONTROL
UNIT
APU FUEL APU LP FUEL
FROM PUMP ISOLATION DRAIN/VENT
LEFT TANK VALVE VALVE
Figure 41 Fuel Control Logic

01|ï30|FuelFeed|L2 Page 66
49ï30
CENTER TANK
APU LP APU FUEL

ISOL VLV PUMP
FUEL X FEED VLV
PRESS SW/ APU FUEL

SENSOR SUPPLY
FUEL DRAIN
VENT VALVE
CONTROL APU INLET
RELAYS PRESS SW/
(LOGIC) VENT FUEL SENSOR FCU
LINE SWITCH
APU FUEL SYSTEM

MASTER SW “ON“ AND
S/D FUNCTION
ECB
MASTER SW “ON“ SIGNAL

CONTROL SYSTEM
ECAM APU PAGE

Figure 42 APU Fuel Feed System
01|ï30|FuelFeed|L2 Page 67
49ï30
APU FUEL FEED SYSTEM COMPONENT DESCRIPTION

APU Fuel Feed Pump 4QC and Canister 9QM APU Fuel Low Press. Valve 3QF
It is a centrifugal pump driven by a singleï phase 115V AC motor. It is installed has two 28V DC motors. It will operate with no time delay if failure of one of the
at the rear spar of the wing centerïbox, in the APU fuel feed line (which motors occurs. It is installed on the rearïspar of the wing centerïbox,
connects with the left mainïengine fuelïfeed line). downstream of the APU fuelïfeed pump 4QC.
For normal operation, the NORMAL AC 1 busbar 103 XP (115V AC) supplies The valve closes automatically to shutoff the APU fuelïfeed valve when:
the pump motor. When the NORMAL AC 1 busbar is not energized, the static S the APU SHUTOFF switch 1KL (guarded red) on the external power panel
inverter busbar 901 XP (115V AC) supplies the pump motor. 108VU forward of the nose landing gear bay, is operated,
The APU fuel pressure switch 7QC (installed adjacent to the pump) monitors S the APU FIRE switch (guarded red) on module 1WD (panel 20VU) on the
crossfeed line pressure (close to the APU pump inlet) and automatically overhead panel is operated,
controls the pump operation.
S an APU shutdown occurs on the ground after a fire detection,
S any other protective shutdown occurs.
APU Fuel Pressure Switch 7QC
The switch operates on fuel absolute pressure in the crossfeed line. When the APU Fuel Vent PB Switch 8QC
pressure in the crossfeed line decreases to 22PSI, it closes to operate the APU
fuelïfeed pump 4QC. When the pressure in the crossfeed line increases to 23 is installed on the front firewall in the APU compartment. When operated, it
PSI, it opens to stop the APU fuelïfeed pump operation. opens the fuel low press. valve and permits the APU fuelïfeed pump 4QC to
operate on the ground (to purge the fuelïfeed line during maintenance of the
system).
A/C AD
CROSSFEED
REAR SPAR FUEL LINE
APU FUEL FEED PUMP 4QC

STA1869/FR42 WITCH CANISTER 9QM
APU FUEL PRESSURE

A SWITCH 7QC
LOCATION IN A/C: ACTUATOR FUEL LP VALVE 3QF
SEE NEXT FIGURE VALVE APU FUEL LP 14QM
Figure 43 APU Fuel Feed Components (1)
02|FeedSys Comps|L3 Page 68
49ï30
VENTED SHROUD FITTED AROUND THE STA3730/FR80

NOTE: APU FUEL
HOSE (ALUMINIUM ALLOY TUBE 1.5 in DIA.) VENT SWITCH
DOUBLE WALLED FLEXIBLE HOSE,
0.5/1.75 in DIA. STA3366/FR70
FLEXIBLE HOSE, 0.5 in DIA.

(TEFLON WITH SILICON FIBERGLASS FIRE SLEEVE)
DRAIN MAST
STA2136/FR4
STA2083/FR4 7
STA1869/ 6
FR42 Z140
Z150
Z160
Z170
A
SEE PREVIOUS FIGURE
FOR DETAILS
Z310
DRAIN TUBE

49ï30
APU Inlet Low Press. Switch 5030QM

The switch is installed in the APU compartment at the fuel inlet connection to
the FCU. It operates on fuel absolute pressure in the APU fuelïfeed line at the
inlet to the FCU.
When it operates, it transmits a signal to the ECB (Electronic Control Box)
59KD and an ECAM Message ”LOW FUEL PRESSURE” on the APU Page
appears.
The switch closes when the inlet pressure decreases to 16 psi. The switch
opens when the inlet pressure increases to 17psi.
Drain and Vent Valve 5040QM

The Valve is installed in the APU compartment at the fuel inlet connection to
the FCU. It permits the APU fuelïfeed line to be drained of fuel and bled of air
during maintenance of the system.
For this the APU Fuel Vent PB Switch has to by pressed.
Fuel feed line

The fuel feed line connects the mainïengine fuelïfeed system and crossfeed
line, at the wing centerïbox rear spar. It supplies fuel to the APU fuel inlet
connection at the APU compartment.
The APU fuelïfeed line installation includes:
S a 12.7mm (0.5 in.) diameter aluminiumïalloy tube, installed from the cross
feed line to the top of the wing center tank (immediately forward of FR42),
S a doubleïwalled vented hose, installed from FR42 to FR80,
S 12.7mm (0.5 in.) diameter highïpressure Teflon flexible hose which
incorporates spacing rings to support and locate the hose in its tube.
S a fire sleeve from FR80 to the APU fuel inlet connection.
S a 9.525mm (0.375 in.) outside diameter drain tube, which connects to the
vented shroud, at its lowest point (top of the wing centerïbox, immediately
forward of FR42).
S a drain mast at FR47, which connects to the drain tube. It permits the fuel to
drain overboard if a fuel leak occurs in the hose.

49ï30
SECTION
B-B
SPACER
DRAIN AND VENT RING
VALVE (TBD)
APU INLET LOW PRESSURE

SWITCH
SAFETY
WIRE
FCU
LOCKING
SPRING
APU FEED LINE

HOSE COUPLING
BONDING SAFETY WIRE
B
JUMPER
HOSE
’O’ RING SPACER

B ’O’ RING RING
COUPLING SHROUD
SLEEVE
APU FUEL CONTROL APS 3200
49ï32
49ï32 APU FUEL CONTROL

SYSTEM DESCRIPTION
General Operation
The APU fuel system operates fully automatically and has no external controls. 1. Set the MASTER SW 14KD to ON. When you push the APU START
The APU fuel system includes: switch 2KA, the engine starts to turn. After approx. 1.5 sec. the ECB 59KD
S a FCU (Fuel Control Unit) 4005KM2, energizes the fuel solenoid valve to the open position. Fuel from the servo
valve of the FCU flows through the pilot injector and purge valve of FDDVA.
S a FDDVA (Flow Divider and Drain Valve Assembly) 4005KM1,
From the FDDVA it is sent to the pilot fuel nozzles. After another 1.5 sec.
S a Low Pressure (Inlet) Filter the ECB 59KD energizes the ignition system, combustion occurs and the
engine continues to accelerate.
Fuel Control Unit
2. At 55% engine speed, the ECB 59KD deïenergizes the exciter and the
The FCU together with the FDDVA, schedule the fuel flow to the APU.
starter motor 8 KA. The engine continues to accelerate under its own
The FCU also supplies highïpressure fuel to the bleed control valve and to the power to governed speed. The speed control function in the ECB 59KD
IGV (Inlet Guide Vane) Actuator to give the necessary power to position the transmit a signal to the FCU. The FCU then increases or decreases the
load compressor IGVs and the bleed control valve. fuel flow as necessary for the changes in load. This keeps the speed of the
The fuel which is supplied to the FCU passes through the centrifugal low APU constant.
pressure pump to the inlet fuel filter and into the highïpressure fuel pump. 3. As the engine accelerates, the ECB 59KD transmits a signal to the servo
The output from the highïpressure fuel pump is supplied to the: valve in the FCU to control the metered fuel flow. The fuel acceleration
S Actuator Pressure Regulator control in the ECB 59KD keeps the necessary fuel flow until the engine
gets to governed speed.
S Servo Valve
At low speed all pump flow goes to the pilot injectors. The engine
Metered fuel flows through the Constant ∆P Valve, 3-Way Fuel Solenoid Valve
accelerates, the fuel flow increases to a set level and the main injector valve
and comes out of the discharge port. The differential pressure indicator gives a
of the FDDVA opens. This permits more fuel to flow. The ECB 59KD, which
signal to the ECB for CFDS when the filter is clogged. The filter bypass valve
controls the fuel pressure, also keeps the IGV actuator in the closed
permits continued operation with a clogged filter.
position.
Flow Divider and Drain Valve Assembly
APU Shutdown
The FDDVA (Flow Divider and Drain Valve Assembly) together with the FCU,
When APU shutdown is initiated (automatically or manually controlled
schedule the fuel flow to the APU. The FDDVA controls the fuel flow to the
shutïdown), the ECB deïenergizes the 3 way solenoid valve which closes the
main– and the pilot manifolds and drains them at APU shutdown. Fuel from the
fuel supply to the pilot and main injectors. The APU decelerates.
FCU is supplied to the inlet port of the fuel flow divider during APU starting and
normal operation. Fuel is supplied from the pilot fuel port to the pilot fuel The ECB also deïenergizes the fuel servo valve which ” closes“ the fuel supply
manifold during engine starting and operation. Fuel supply begins from the to the 3 way solenoid valve. The excess fuel then returns to the HP pump inlet
main fuel port to the main fuel manifold when the engine reaches approxi. 20% through the constant Delta P valve and the fuel filter.
speed during starting. Fuel continues to be supplied from this port during APU The fuel remaining in the pilot fuel manifold and injectors is purged to the
operation. During engine shutdown, fuel is purged from the pilot fuel nozzles exhaust.
and flows from the purge port of the fuel flow divider to the exhaust.
03|ï32|Fuel CTL|L2 Page 72

49ï32
PILOT FUEL
FCU INJECTORS (3)
BLEED CTL
FILTER
""""
""""
VLV ACTR
""""
IGV ACTR
""""
BYPASS PRESSURE
VALVE
""""
""""""
PRESSURE REGULATOR
FUEL DRAIN
RELIEF VALVE
""""""
DPI TO EXHAUST
SYSTEM
""""""
FUEL SERVO 3ïWAY SOL VLV
PILOT (PURGE)
""""""
"""""""""
VALVE INJECTOR
AND DRAIN
""""""
"""""""""
VALVE
FUEL INLET FUEL FLOW
""""""
"""""""""
FROM MAIN DIVIDER AND
INJECTOR
""""""
""""""""" " """"
AIRCRAFT HP PUMP VALVE DRAIN VALVE
ASSEMBLY
"""""""""
""""""""" """""
"""""
FUEL LOW
PRESSURE
SWITCH
CONSTANT """""""""
""""""""" """""
"""""
"""""
∆P-VALVE
"""""
LP PUMP
FUEL DRAIN
VENT VALVE
APU SPEED (%RPM)

DRAIN
EGT
P1 MAIN FUEL
T1 INJECTORS (6)
Figure 46 Fuel System Schematic

03|ï32|Fuel CTL|L2 Page 73
49ï32
FUEL CONTROL UNIT COMPONENT DESCRIPTION

The main features of the servo valve are
Low Pressure Fuel Pump
S Type: Torque motor
The low pressure fuel pump ensures a pressure increase in order to obtain a
S Current: 0 ï I 00 mA
positive pressure supply at the inlet of the high pressure pump to avoid
cavitation. S Metered flow: 0 ï 180 kg/h (O ï 395 PPH).
The pump is mechanically driven at the same speed as the high pressure
pump by a splined shaft (driven by one pinion of the gearbox). 3 Way Solenoid Valve
The drive shaft is provided with a seal and a drain connected to the drain The valve opens and closes the fuel supply for starting and shutdown.
system. The solenoid valve is energized open (control from ECB).
When the valve closes, the fuel returns to the inlet side of the high pressure
High Pressure Fuel Pump fuel pump.
The high pressure fuel pump supplies a fuel flow always higher than the APU
requirements. The excess fuel is returned to the pump inlet by the constant Constant Delta-P Valve
Delta P valve. The pump is provided with a pressure relief valve.
This valve keeps a constant pressure difference across the servo valve so as
to obtain a flow only depending upon the metering valve position.
Fuel Filter
The valve is subjected to upstream pressure on one side and downstream
The filter is located at the outlet of the low pressure pump. pressure plus the force of a spring on the other side. The valve position
The filter includes the following components : determines the amount of fuel which is returned to the inlet of the pump. In so
doing, the valve keeps the Delta P constant and reduces the load on the pump
S A Filter element to remove foreign material from Fuel.
The Delta P setting of the constant Delta P valve is of 689 kPa (100 PSID).
S An impending blockage Delta P indicator to indicate the preïblockage
situation of the filter element. (at 7PSID)
Pressure Regulator
S A byïpass valve to ensure the fuel supply in the event of filter blockage.
The pressure regulator provides the hydraulic fuel supply to the inlet guide
ServoïValve vane actuator and to the bleed control valve actuator.
The regulator controls a constant delivery pressure.
The servoïvalve meters the, fuel during starting and normal running conditions.
The delivery pressure of the pressure regulator is of 1724 kPa (250 PSI).
The valve consists of a servo coil which actuates a fuel metering valve (clevis
type). From 0 to 60 %, the pressure regulator is shutïoff. It opens above 60 %
The servo is electrically supplied by the ECB. The current operates the clevis
valve which determines the fuel flow.
During starting, the ECB and servoïvalve meter an increasing fuel flow to
obtain the acceleration.
In normal running conditions, the fuel flow is metered to obtain a constant
speed of the APU.
04|Fuel CTL|L3 Page 74

49ï32
FUEL PUMPS
PRESS. REGULATOR
PRESSURE
CENTERING PIN RELIEF VALVE
3 WAY FILTER
SOLENOID BY-PASS
VALVE VALVE
(UNDER COVER)
CONSTANT DP TO SERVOVALVE
VALVE ACTUATORS
FUEL INLET
TUBE
RETURN FROM
SERVOVALVE
DRAIN ACTUATORS
FILTER
SERVOVALVE IMPENDING
BLOCKAGE
∆P INDICATOR
Figure 47 Fuel Control Unit Components
49ï32
FCU OPERATION
General Running condition
The operation is considered in the following operating phases: starting, running S Stabilized condition
condition (stabilized and transient), shutdown. The pumps supply a flow higher than the APU requirements. The fuel flow is
metered by the servo valve according to the ECB programme. The excess
Starting
fuel is returned to the inlet side of the HP pump through the constant Delta
When APU starting is selected: P valve and the fuel filter.
S The starter motor operates and cranks the APU rotating assembly S Transient condition
S The ignition exciter operates and supplies high voltage to produce sparks at When the load applied to the power section changes, the rotation speed
the tip of the two igniter plugs changes. The ECB senses the change and implements a signal sent to the
S The 3 way solenoid valve is energized to open the fuel flow N > 3% servo valve. The fuel flow is thus metered to keep the rotation speed
S The servo valve is electrically supplied to control the fuel flow. constant.
The fuel from the aircraft fuel system is supplied by the low pressure and high S Shutdown
pressure pumps through the servo valve and the 3 way solenoid valve. When APU shutdown is initiated (automatically or manually controlled
When the fuel pressure reaches approximately 138 kPa (20 PSI), the flow shutïdown), the ECB deïenergizes the 3 way solenoid valve which closes
divider allows fuel supply to the pilot injectors. The fuel sprayed is ignited by the fuel supply to the pilot and main injectors. The APU decelerates.
the sparks of the igniter plugs. The ECB also deïenergizes the fuel servo valve which ”closes“ the fuel
supply to the 3 way solenoid valve. The excess fuel then returns to the HP
During starting, pump inlet through the constant Delta P valve and the fuel filter.
The fuel flow is controlled by the ECB and the servo valve. The fuel remaining in the pilot fuel manifold and injectors is purged to the
At selfïsustaining speed, the starter and the ignition system are deïactivated exhaust.
and the APU continues to accelerate.
At nominal speed, the “ECBïservo valve” assembly governs a constant speed
by metering the fuel flow.
The high pressure fuel pump also supplies the pressure regulator for the fuel
operated actuators of the pneumatic control system (Inlet guide vane control)
and (Bleed valve control).

49ï32
PILOT FUEL
MANIFOLD PILOT INJECTOR
PILOT INJECTOR
ÉÉÉÉ
AND PURGE VALVE LEGEND:
ÏÏÏÏ DRAIN PURGE

TO EXHAUST
ÏÏÏÏ
ÉÉÉÉ
ÏÏÏÏ
DRAIN
FUEL HIGH PRESSURE
FUEL LOW PRESSURE
FLOW DIVIDER REGULATED PRESSURE

METERED FUEL
SEAL DRAIN
MAIN INJECTOR (REF 49ï17ï00)
SOLENOID VALVE
VALVE
TO IGV ACTUATOR FROM IGV ACTUATOR
AND BCV ACTUATOR AND BCV ACTUATOR
ÉÉÉÉÉÉÉÉÉ
PRESS
SERVO REG REGULATOR
ÉÉÉÉÉÉÉÉÉ
VALVE
ÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉ HP FUEL
ÉÉÉÉÉÉÉÉÉ
PUMP
ÉÉÉÉÉÉÉÉÉ
ÉÉÉÉÉÉÉÉÉ LP FUEL
PUMP
ÏÏ SEAL DRAIN
FILTER BYPASS
DIFFERENTIAL ELEMENT FILTER
PRESSURE RELIEF
VALVE VALVE
FCU FUEL FROM

AIRCRAFT FUEL
SUPPLY
Figure 48 APU Fuel Schematic (FCU)

49ï32
START FUEL FLOW CONTROL OPERATION

General
This function meters the fuel flow during APU starting.
Components
S Speed sensors, the EGT thermocouples, the air inlet pressure and
temperature probes
S ECB (Electronic Control Box)
S Fuel servo valve.
System Operation
The fuel flow programme has two phases
S A first phase: Until a rise of EGT (Delta EGT) higher than 50’F is detected
S A second phase: From Delta EGT detection to 95 % speed + 2 seconds.
During the first phase, the fuel supply is mainly used to fill the manifold. The
fuel flow is metered as a function of the rotation speed only.
During the second phase, the fuel is scheduled as a function of two selectable
programmes (automatically selected):
S One programme controls the fuel flow rate after comparison of the actual
acceleration with an acceleration rate datum
S The other programme controls the fuel flow rate after comparison of the
actual EGT with an EGT datum variable with the rotation speed.

49ï32
PILOT FUEL MANIFOLD

AND INJECTORS
FROM FUEL CONTROL

FLOW
AIRCRAFT UNIT PURGE TO EXHAUST
DIVIDER
FUEL SYSTEM (FUEL SERVOVALVE)
MAIN FUEL MANIFOLD

AND INJECTORS
CONTROL
SYSTEM
(ECB)
ROTATION SPEED
N%
N EGT P1 T1
100
95
2ND PHASE
∆EGT
(50 _F)
1ST PHASE
0
TIME
Figure 49 APU Start FF Control Schematic

49ï32
FLOW DIVIDER OPERATION

Purpose
The flow divider distributes the fuel from the fuel control unit to the pilot and
main injectors. It also ensures the purge of the pilot injectors during “APU
shutïdown. FUEL INLET
(FROM FUEL CONTROL UNIT)
Location
The flow divider is installed on the left side of the combustor housing.
In the fuel system, the flow divider is located downstream of the 3 way solenoid
valve.
System Layout
The flow divider mainly consists of: MAIN INJECTOR
S A pilot injector and purge valve set at approx. 20 PSID VALVE
(1380 kPa/200 PSID)
S A main injector valve set at approx. 200 PSID FILTER FUEL OUTLET
S A filter screen (located at the fuel inlet of the flow divider) SCREEN TO MAIN
INJECTOR
SYSTEM OPERATION
MANIFOLD
Starting
When APU start is selected, the supply pressure increases and, at 20 PSID,
the pilot injector valve opens, allowing fuel supply to the pilot injectors. All
pump flow goes to the pilot injectors.
When the pressure reaches 200 PSID, the main injector valve opens allowing
fuel supply to the main injectors without fuel pressure drop in the system.
Normal running condition FUEL OUTLET FUEL OUTLET
TO EXHAUST SYSTEM TO PILOT
The two valves are in the open position and the fuel is allowed to flow to the
(PURGE) INJECTOR
pilot injectors and to the main injectors. The continuous fuel flow through the
MANIFOLD
pilot injectors prevents coking.
Shutdown PILOT INJECTOR

As the Fuel pressure decreases, the two valves close. The Fuel remaining in AND
the pilot injectors is purged to the exhaust by compressed air flowing through PURGE VALVE
the purge valve. (138 kPa/20 PSID)
Figure 50 Flow Divider

49ï32
FUEL CONTROL
UNIT
3 WAY SOLENOID VALVE
PILOT FUEL MANIFOLD
AND INJECTORS
FLOW PURGE TO EXHAUST

DIVIDER
MAIN FUEL MANIFOLD

AND INJECTORS
PILOT INJECTOR
AND PURGE
VALVE (20PSID)
NORMAL
STARTING RUNNING SHUT-DOWN
CONDITION
MAIN INJECTOR
VALVE (200PSID)
Figure 51 Flow Divider Operation
49ï32
FUEL MANIFOLDS AND INJECTORS COMPONENT

DESCRIPTION
Pilot Fuel Manifold
The pilot fuel manifold delivers the Fuel from the flow divider to the 3 pilot
injectors which spray the fuel into the combustion chamber to permit starting. FLOW
DIVIDER
The pilot fuel manifold also supplies pilot fuel injectors with fuel during normal
running condition.
PILOT FUEL
The pilot fuel manifold is mounted around the combustor rear face close to the MANIFOLD
main fuel manifold.
Main Fuel Manifold
The main fuel manifold provides the fuel supply from the flow divider to the 6
main injectors which spray the fuel into the combustion chamber. MAIN FUEL
MANIFOLD
The main fuel manifold is mounted around the combustor rear face close to the
pilot fuel manifold.
Pilot Fuel Injectors
The 3 pilot injectors spray the fuel into the combustion chamber to permit
starting. They also remain in operation during normal running conditions.
Main Fuel Injectors
PILOT FUEL
The 6 main injectors spray the fuel into the combustion chamber to provide INJECTOR
efficient burning. The fuel that enters the injector is mixed with compressed air.
The flow of fluid is “broken” by shearing effects and thus, the fuel is finely
sprayed into the combustion chamber. The 6 airblast injectors penetrate
radially into the combustor and the spraying provides a stable and efficient MAIN FUEL
combustion. INJECTOR
Drain (Purge)
At APU shutdown, as the fuel pressure deceases, the two valves (main and
pilot injector valve) close. The fuel remaining in the pilot injectors is purged to
the APU exhaust by compressed air flowing through the purge valve.
Figure 52 Combustor Housing (LH-Side)

49ï32
FUEL INLET
(FROM PILOT FUEL PILOT INJECTOR
MANIFOLD) BODY
INJECTOR BODY
HOUSING
FUEL INLET (FROM

MAIN FUEL MANIFOLD)
FUEL FILTER
MAIN INJECTOR BODY
COMPRESSED
AIR (FROM PS
COMPRESSOR)
COMPRESSED
AIR (FROM PS
COMPRESSOR)
PILOT FUEL INJECTOR

FUEL SPRAYED INTO
THE COMBUSTOR
(SHEARING EFFECTS)
AIR BLAST
INJECTOR
MAIN FUEL INJECTOR
Figure 53 Fuel Manifolds and Injectors

AIR APS 3200
49ï50
49ï50 AIR SYSTEM

AIR SYSTEM DESCRIPTION
Purpose Component Location
The air system provides compressed air to the aircraft on the ground and in The inlet guide vane system components are located on the right upper part of
flight. the APU on the load compressor casing. The inlet guide vanes are located in
the load compressor air inlet.
Main Features
The air bleed system components are located on the right lower part of the
S Flow: 1.2 kg/s (2.6 PPS) APU at the scroll outlet.
S Pressure: 400 kPa (59.4 PSI) All the sensors are located on the APU.
S Temperature: 232 _C (450 _F).
Interfaces
Main Components S The ECB
Two systems are considered: S The aircraft pneumatic system
S The inlet guide vane system which operates so as to avoid overtemperature S The APU fuel system.
of the power section.
NOTE: The air system also includes the Accessory Cooling with Ducts,
It mainly includes:
Cooling Fan and Compartment Cooling Valve.
ï a servo valve
ï an actuator
ï an inlet guide vane control mechanism and the inlet guide vanes.
S The air bleed system which operates to deliver air while avoiding
compressor surge.
It mainly includes:
ï a servo valve
ï an actuator
ï a bleed control valve.
These two systems also include sensors (for temperature and pressure) and
uses fuel as the hydraulic fluid.
They are both controlled by the ECB.
01|ï50|Air|L2 Page 84
AIR APS 3200
49ï50
BLEED CONTROL VALVE OPEN (delivery)

S L
U O
R A
FUEL G D
E
TO AIRCRAFT
PNEUMATIC CLOSE (discharge)
SYSTEM
IGV ACTUATOR
FUEL
FUEL
DISCHARGE
PRESSURE SIGNAL
∆P SENSOR SIGNAL TO APU FRONT
AND REAR
BEARING
TO APU
COMP
OIL
COOLER
AIR/OIL
SEPARATOR
GEARCASE VENT AIR
TO OVBD
AIR INLET PRESSURE &
INTAKE TEMPERATURE SENSOR
PLENUM
Figure 54 Air System Schematic

01|ï50|Air|L2 Page 85
AIR APS 3200
49ï50
INLET GUIDE VANE SYSTEM OPERATION

Operation Principle Actuator
The inlet guide vane system controls the air flow into the load compressor in The actuator consists of a spool valve moving in a sleeve. The spool valve is
order to avoid overtemperature of the power section. subjected on one side to the fuel pressure and on the other side to the
The ECB implements a current signal in relation to the rotation speed, the EGT modulated fuel pressure supplied by the servo valve.
(Exhaust Gas Temperature) and to other parameters such as the operation The actuator housing also includes a linear bearing which has double dynamic
mode MES (Main Engine Start) or ECS (Environmental Control System) and seals with a chamber drain in between.
pressure and temperature parameters (OAT, OAP). This current signal is sent The spool valve is integral with the actuator piston which is connected to the
to the servo valve and causes the angular displacement of the spill valve which control mechanism.
controls the leak of the potentiometric jet. In stabilized condition, there is an
The position of the actuator is fed back to the ECB by a LVDT (Linear Voltage
average current (of approx. 50 mA) corresponding to a stabilized position of the
Differential Transformer) located inside the spool valve.
actuator.
The servo valve then delivers to the actuator a modulated fuel pressure in IGV Control Mechanism and IGVs
relation to the signal. The inlet guide vanes are mounted in a support assembly. Each vane has a
sector gear engaged in a common ring gear which is driven in rotation on the
support assembly by the inlet guide vane actuator. Thus, all vanes rotate
When the modulated fuel pressure varies, it creates a difference of pressure simultaneously.
between the two sides of the spool valve which moves and drives the actuator When the inlet guide vanes are fully open, the maximum air flow is delivered to
piston. The linear voltage differential transducer sends the spool valve position the load compressor.
signal to the ECB to control the operation of the actuator.
APU Starting
The piston displacement causes the displacement of the arm of the rack and
pinion system which rotates. The rack and pinion system rotation then causes During start, the inlet guide vanes are in the closed position to reduce the
the rotation of the inlet guide vanes through their sector gears. resisting torque of the load compressor.
The load compressor can then supply compressed air either to the exhaust In Flight Operation
system or to the aircraft pneumatic system according to the pilot selection and During flight operation, the opening or closing of the inlet guide vanes depends
operating conditions. on the aircraft pneumatic system requirements.
Servo Valve In case of EGT exceeding the limit, the inlet guide vanes also automatically
The servo valve consists of a flap valve which is opposed to a potentiometric move to the closed position to reduce the resisting torque of the load
jet. The servo valve has a fuel pressure inlet, a modulated fuel pressure outlet compressor.
and a fuel return outlet. The fuel pressure depends on the position of the servo In case of inlet guide vane control failure, the vanes automatically move to the
valve which is controlled by two solenoids. The solenoid control current closed position.
(0ï100 mA) is sent by the ECB in relation to reference signals.
02|IGV Ops|L3 Page 86

AIR APS 3200
49ï50
IGV ANGULAR POSITION (_)
START .......... -10_ CLOSED

ECS
IGV MODE EGT N(100%) ECS MIN ....... +40_ ...................
SERVO MES FUEL FUEL FUEL
OAT RETURN PRESS DRAIN
VALVE ECS MAX ...... +83_ FULL OPEN
OAP
ECB
mA ÜÜÜ
ÜÜÜ
MES .............. +83_ FULL OPEN
ÜÜÜ
ÜÜÜ
INTERFACES
ÜÜÜ
ÜÜÜ
ÜÜÜÜÜÜÜÜÜÜ mA
ÜÜÜ
ÜÜÜÜÜÜÜÜÜÜ
ÜÜÜ
POSITION
ÜÜÜ
ÜÜÜ
ÜÜÜÜÜÜÜÜÜÜ EGT
ÜÜÜ
0 0
SIGNAL
100 mA 0 mA
ÜÜÜ
IGV
ÜÜÜ
ACT
ÜÜÜ
LVDT
ÜÜÜ
ÜÜÜÜ
ÜÜÜÜ
REDUCED PRESSURE
ÜÜÜÜ
IGV IGV
MODULATED PRESSURE OPEN CLOSED
FUEL RETURN
IGV CLOSING
IGV OPENING
Figure 55 IGV Operation Schematic

02|IGV Ops|L3 Page 87
AIR APS 3200
49ï50
AIR BLEED SYSTEM OPERATION

Bleed Valve
The valve is of butterfly type. It has a compressed air inlet, exhaust and aircraft Discharge to Exhaust
outlets. It mainly consists of a flap which directs the compressed air to the The compressed air is discharged to the exhaust system to reduce the
exhaust system when closed or to the aircraft pneumatic system when open. resisting torque of the load compressor. According to inlet signals (pressure
The diverter valve also includes a visual position indicator. and rotation speed signals) the ECB implements a current signal. This current
The flap is driven in rotation by a rotary actuator. signal is sent to the servo valve and causes the angular displacement of the
spill valve which closes the leak of the potentiometric jet. The modulated fuel
Servo Valve pressure then increases. This increased modulated fuel pressure causes a
The servo valve consists of a spill valve which is opposed to a potentiometric difference of pressure between the two sides of the spool valve. The spool
jet. The servo valve has a pressure inlet, a modulated fuel pressure outlet and valve then moves and causes the actuator piston displacement. The LVDT
a fuel return outlet. The fuel pressure depends on the position of the spill sends the spool valve position signal to the ECB to control the operation of the
valve which is controlled by two solenoids. actuator. The linear motion of the actuator piston is transformed into angular
motion by the rotary actuator in order to set the flap in the discharge position.
The solenoid control current (Oï100 mA) is sent by the ECB according to
reference signals. The compressed air is then discharged to the exhaust system. The system
also discharges the compressed air into the exhaust to prevent surge during
Actuator APU shutdown.
The actuator consists of a spool valve moving in a sleeve. The spool valve is
Compressed Air Delivery to Aircraft
subjected on one side to the fuel pressure and on the other side to the
modulated fuel pressure delivered by the servo valve. According to inlet signals (pressure and rotation speed signals) the ECB
implements a current signal. This current signal is sent to the servo valve and
The actuator housing includes a linear bearing which has double dynamic seals
causes the angular displacement of the spill valve which opens the leak of the
with a chamber drain in between.
potentiometric jet. The modulated fuel pressure then decreases.
The position of the actuator is fed back to the ECB by a LVDT (Linear Voltage
This decreased modulated fuel pressure causes a difference of pressure
Differential Transformer) located inside the spool valve.
between the two sides of the spool valve. The spool valve then moves and
The spool valve is integral with the actuator piston which is mechanically causes the actuator piston displacement. The LVDT sends the spool valve
connected to the rotary actuator of the valve. position signal to the ECB to control the operation of the actuator. The linear
motion of the actuator piston is transformed into angular motion by the rotary
actuator in order to move the flap to the delivery position.
The system then delivers the compressed air to the aircraft pneumatic system.
In case of a control system failure, the valve automatically moves to the
discharge position.
NOTE: In stabilized condition, there is an average current
(of approx. 50 mA) corresponding to a stabilized position of the
actuator.
03|AirBleed Ops|L3 Page 88

AIR APS 3200
49ï50
P/P N(100%) FUEL FUEL FUEL The BCV is shown in the

RETURN PRESS DRAIN position:
”OPEN to SURGE ”
ECB
mA
ÎÎÎ
ÎÎÎ
and
”CLOSED to LOAD”
ÎÎÎ
ÎÎÎ
ÎÎÎ
ÎÎÎÎÎÎÎÎÎ ÎÎÎÎ
INTERFACES
ÎÎÎ
REDUCED PRESSURE
ÎÎÎ
MODULATED PRESSURE
POSITION ÎÎÎ
ÎÎÎÎÎÎÎÎÎ
ÎÎÎ
ÎÎÎÎÎÎÎÎÎ
FUEL RETURN
VALVE IN DELIVERY POS
ÎÎÎ
ÎÎÎÎÎÎÎÎÎ
SIGNAL
VALVE IN DISCHARGE POS
ÎÎÎ
ÎÎÎÎÎÎÎÎÎ
100 mA 0 mA
ÎÎÎ
ÎÎÎÎÎÎÎÎÎ
ACTUATOR
ÎÎÎ
ÎÎÎÎÎÎÎÎÎ
LVDT
SERVOVALVE
(LP)
AIRCRAFT P DELIVERY
OUTLET
0.2
DISCHARGE
0.1
G’
0
OPEN (delivery)
BCV POSITION
S L
U START TO DISCHARGE
O
R A BLEED “ON“, NO DEMAND TO DISCHARGE
G D
E BLEED “ON“ + DEMAND FROM 50% TO
CLOSE (discharge) FULL DELIVERY
EXHAUST FLAP
OUTLET BCV POSITION INDICATOR
Figure 56 Air Bleed System Operation Schematic
03|AirBleed Ops|L3 Page 89
AIR APS 3200
49ï50
AIR SYSTEM SENSORS DESCRIPTION

General
The Signals of the sensors are used by the ECB for fuel metering, EGT
limitation and air flow calculation.
Inlet Air Pressure/Temperature Sensor

Inlet Air Pressure and temperature sensor are housed in one sensor assembly
which is located on the air intake plenum.
The inlet air temperature and the inlet air pressure is used by the ECB for
control purposes (fuel metering, EGT limitation, air flow calculation).
In case of failure the condition monitoring parameters are not taken and a back
up value is used. A failure does not directly cause the APU to shutdown,
however it affects several functions (fuel, IGV, etc.).
Load Compressor Discharge Temperature Sensor
The temperature sensor is located on the air discharge duct. The temperature
is measured in order to calculate the bleed air flow condition. The purpose of
measuring the bleed air flow is to control the Bleed Control valve (and then to
avoid load compressor surge).
In case of failure, the ECB commands the Bleed Control Valve to close the
aircraft bleed and to bypass the compressed air to the discharge.
Load Compressor Discharge Pressure Sensors

The pressure Sensors (Delta P and Total P) are assembled together in one
unit and are located on the air intake plenum.
The load compressor discharge pressure sensors give 2 signals, the Delta P
and the total Press. in order to calculate the bleed air flow condition, to control
the Bleed Control Valve (and thus to avoid load compressor surge).
The sensor is also responsible for the revers flow shutdown protection
In case of failure, the ECB commands the Bleed Control Valve to close the
aircraft bleed and to bypass the compressed air to the discharge.
04|Sensors|L3 Page 90
AIR APS 3200
49ï50
PRESSURE MOUNTING
PORT FLANGE
MOUNTING
FLANGE
SENSOR
PRESSURE
TEMPERATURE MOUNTING PORTS
PROBE FLANGE
LOAD COMPRESSOR LOAD COMPRESSOR
INLET AIR TEMPERATURE SENSOR DISCHARGE DISCHARGE
TEMPERATURE SENSOR PRESSURE SENSOR
Figure 57 Air System Sensors
04|Sensors|L3 Page 91
AIR APS 3200
49ï50
ACCESSORY COOLING OPERATION

Cooling Fan
The cooling fan (driven by one of the gears of the gearbox) provides air
circulation for the oil cooler and for the ventilation of the engine compartment.
A cooling fan integral generator serves as a PMG (Permanent Magnetic
Generator) also provides an emergency direct current supply to the electronic
control box, should the Main supply fail.
S Cooling fan rotation speed is 51965 RPM
S Permanent Magnet Generator output is 40V DC (100 % of N).
It is used as an emergency supply to the ECB in the event of a faulty main
supply
S Speed signal for backup of the overspeed protection system: 107 %
S Compartment cooling valve is operated by air pressure to provide
compartment ventilation when the APU is operating.
Location
The cooling fan is located at the top of the gearbox front face and is secured by
a Vïband clamp.
05|AccCooling|L3 Page 92
AIR APS 3200
49ï50
PERMANENT MAGNET FAN OUTLET DUCT

GENERATOR CONTROL BOX (TO OIL COOLER)
FAN INLET DUCT

(FROM AIR INLET PLENUM)
COOLING FAN
ASSEMBLY
COOLING AIR COMPARTMENT VENTILATION
Figure 58 Accessory Cooling Components

05|AccCooling|L3 Page 93
IGNITION AND STARTING APS 3200
49ï40
49ï40 IGNITION AND STARTING

INTRODUCTION
Starter Control
The starting system drives the APU (Auxiliary Power Unit) rotor through a
clutch and gearbox. When the APU speed is 55% rpm, the start logic of the
ECB (Electronic Control Box) cuts off the supply to the start contactors, which
switch off the starter motor. The timed acceleration loop of the ECB causes the
APU to accelerate to reach the governed speed.
Ignition Control
The ignition system is used to ignite and maintain combustion during the start
phase. It operates from initial crank up to 55% rpm.
The ignition system includes the subsequent components:
S One Ignition Unit
S Two Ignition Leads
S Two Igniter Plugs
01|ï40|IGN&Starting|L1 Page 94
49ï40
ECB
STARTER MOTOR
FUEL CONTROL
UNIT
IGNITER PLUGS
FUEL SYSTEM
IGNITION EXCITER COMPONENTS
Figure 59 Ignition and Starting System Layout
01|ï40|IGN&Starting|L1 Page 95
49ï40
IGNITION AND STARTING SYSTEM DESCRIPTION

General Starting Operation
The starting system rotates and accelerates the rotor of the APU to 55 % of the After the start push button is pressed the following sequence occurs:
APU speed. The system also prevents excessive battery power consumption if S The Air Intake Flap is checked to be open
the APU does not start. Three starts, one after the other (with a one minute
S 100ms later the backup start contactor is energized,
interval) are allowed. After a third unsuccessful try the starter motor must cool
down for at least 60 minutes. S 1.5 sec later the gearbox deïoiling valve solenoid, the exciter and the main
start contactor are energized
NOTE: During RAT (Ram Air Turbine) extension, APU starting is
S At N > 3% the 3 way fuel solenoid valve is energized
inhibited by the BCL1 and BCL2 (Battery Charge Limiter), which
prevents operation of the main start contactor. S At N > 15% acceleration control to 100% is initiated,
S At N > 55% the exciter is turned off and the gearbox deï oiling valve
Starting Sequence Initiation solenoid and the main start contactor are deïenergized
The APU MASTER SW and the START switch are installed on the overhead S 5 sec. later the backup start contactor is deïenergized
panel 25VU in the cockpit. The start sequence begins when the MASTER SW
S At N > 95% the surge control is initiated
and then the START switch have been pressed to the ON position. The main
relay is energized when the MASTER SW is pressed. S 2 sec later the APU available signal is activated and the start in progress
signal is deïactivated
S steady state speed control is initiated and APU operates in the run state.
The EGT increases as the APU accelerates, with starter motor assistance.
Both, speed and EGT can be seen on the ECAM APU system display page,
when selected.
The ECB monitors and controls the APU. It will shutdown the APU if the
acceleration rate is not as shown:
ï 0.1 % per sec when gearbox oil temp is below or equal to ï40 _C
ï 0.5 % per sec when gearbox oil temp is greater than 21 _C
S acceleration rate is linear interpolated when ï40 _C and gearbox oil
temperature is below or equal to 21 _C
You can start the APU again if it is shutdown. To do this, the MASTER SW
must be switched off (until the inlet flap has closed) and then ON again,
before each start attempt.
Engagement of the starter motor is prevented when the APU speed is above
7 %, to prevent damage to the APU.
02|IGN&Starting|L2 Page 96
49ï40
BLEED CONTROL
VALVE
FUEL
TO A/C
PNEUMATIC
SYSTEM
COOLING PMG
FAN
G
E
A
R
AC B
25VU GENERATOR
O
X
STARTER
FUEL CTL LUBRICATION

UNIT UNIT
ECAM PAGE
IGNITION
UNIT
IGV CTL
CFDS FLAP CTL
ECB
Figure 60 Ignition & Starting System Schematic
02|IGN&Starting|L2 Page 97
49ï40
COMPONENT LOCATION
Main and Backup Start Contactor
The main start contactor 5KA and the backïup start contactor 10KA are
installed in the 120VU which is located in the rear of the cockpit. In this location
there is also the 400 ampere APU starter fuse installed.
03|Location|L2 Page 98
49ï40
120VU
120 VU
FR13
STA631
MAIN START CONTACTOR (5KA)
BACK UP START
CONTACTOR (10KA)
APU STARTER FUSE 6KA (400A)
Figure 61 Starting System Components (CFDS Monitored)

03|Location|L2 Page 99
49ï40
COMPONENT DESCRIPTION
Starter Motor
The starter motor 8KA is a series wound DC electric motor with four poles and
four brushes, and has a maximum speed of 17600 rpm. Both the positive and
negative terminals are insulated.
It is equipped with a visual and an electrical brush wear indicator. The visual
indicator pin protrudes up into a clear plastic cover. As the brush with the
indicator pin wears, the pin goes into the cover until it becomes flush inside the
cover. When the pin is flush, it is time to remove the starter motor and replace
the brushes. START CONTACTOR 5 KA
A voltage sense connector is internally wired to the positive terminal cable (this BACKUP START 10 KA
voltage signal is used by the ECB). CONTACTOR
The starter motor weighs approx. 10 pounds and is attached to the gearbox FUSE APU START 6 KA
with a Vïclamp. SUPPLY
The starter motor operates on 28V DC with a normal starter voltage being
approx. 18V DC. It drives the APU rotor to 55% of the APU speed through a
clutch assembly between the motor and the gearbox. At 55 % APU speed the
electrical power is removed from the starter motor.
Starter Sprag Clutch

RELAY BOX 103VU RELAY BOX 107VU
Two operating phases are considered: starter motor engaged and starter motor – RELAY APU MAIN 4KD
– RELAY APU AVAIL 6KD
disengaged.
– RELAY APU FUEL PUMP 50C
S Starter motor engaged – RELAY APU FUEL LINE VENT 60C
During start, the starter motor applies torque to the inner race; the sprag – RELAY FIRE EMERG. STOP 5WF
pawls pivot and lock the two races which accelerate together. – RELAY FIRE EMERG. STOP 6WF
– RELAY APU FUEL PUMP SUPPLY 90C
S Starter motor disengaged
At selfïsustaining speed, the electrical supply to the starter motor is
deïenergized while the APU continues to accelerate. The sprag pawls
disengage and the centrifugal force keeps them outward to prevent friction
against the inner race.
Start Contactor and Backup Start Contactor
The start contactor 5KA and the backup start contactor 10KA are installed on
rack 120VU, rear of the cockpit. These are heavy duty contactors that switch
electrical current to the starter motor 8KA.
Figure 62 Component Location
04|IGN Components|L3 Page 100

49ï40
PREFORMED
PACKING
POSITIVE AND NEGATIVE SPRAG PAWL
TERMINALS (“ENGAGED“) OUTER RACE
STARTER MOTOR APU

BODY
INTERFACE
V-CLAMP STARTER
ATTACHMENT STARTER MOTOR ENGAGED
SPRAG PAWL
APU (“DISENGAGED“)
VISUAL BRUSH
ELECTRICAL BRUSH WEAR INDICATOR
WEAR AND VOLTAGE INDICATOR
STARTER
START CONTACTORS
STARTER MOTOR DISENGAGED
- +
STARTER SPRAG CLUTCH
BATTERY OPERATION
STARTER VOLTAGE INDICATION

MECHANICAL DRIVE
ECB
BRUSH WEAR INDICATION
Figure 63 Starter Motor and Sprag Clutch
49ï40
Ignition Exciter
The ignition exciter is a sealed metal box assembly with a mounting bracket on
one side.
Power is supplied to the ignition exciter through a multiïpin electrical connector
installed on one end of the box. The two igniter leads connect the two
connectors, located on the opposite end of the box, to the igniters. The unit is
shopïrepairable only.
The ignition exciter transforms the low DC voltage into a high energy supply for
the igniters.
Ignitor Plug
Two igniter plugs produce the sparks required to ignite the fuel during the initial
phase of starting. Two igniter cables carry high voltage current from the ignition
exciter to the igniter plugs.
The two igniter plugs are located at the rear of the combustor housing close to
the two pilot fuel injectors:
S One at 5 o’clock
S One at 9 o’clock

49ï40
FLOW DIVIDER
IGNITERS (2) COMBUSTOR HOUSING

REAR FACE
IGNITION EXCITER
IGNITER CABLE IGNITER SPARKS IN

THIS AREA
WIRE FROM ELECTRODE
TANK CAPACITOR
SHIELD
CONDUCTOR MOUNTING
(GROUND ) FLANGE ELECTRODE INSULATOR
Figure 64 Ignition Components

ENGINE CONTROLS APS 3200
49ï60
49ï60 ENGINE CONTROLS

GENERAL
Functions
The functions of the APU Control System FADEC (Full Authority Digital
Electronic Controller) are:
S To keep the power unit rotation speed constant so as to obtain a constant
AC generator frequency output,
S to protect the power unit from overtemperature,
S to avoid load compressor surge,
S to ensure a quick and safe start of the power unit,
S to provide the sequences of the operating states,
S to protect the APU in case of a component defective operation and
S to ease the APU maintenance by supplying information for trouble shooting,
engine condition and life (historical data retention).
Main Features
S FADEC
S Single computer
S Electrical supply from the aircraft DC system and the APU Generator
01|ï60|CTL System|L1 Page 104

49ï60
APU CONTROL
- CONSTANT ROTATION SPEED
N 100 %
- EGT LIMITATION
- LOAD COMPRESSOR SURGE
PROTECTION
- QUICK AND SAFE START
- OPERATION SEQUENCES
AIRCRAFT
CONTROL PANELS
APU MAINTENANCE
- TROUBLE SHOOTING
- CONDITION MONITORING DATA
- HISTORICAL DATA RETENTIONS
APU PROTECTION
- SHUTDOWN ELECTRONIC CONTROL BOX
- INDICATION
APU ACCESSORIES
Figure 65 APU Control System
01|ï60|CTL System|L1 Page 105
49ï60
ECB BITE
General Power up test (POST)
The ECB is a fully digital electronic controller. It does self tests, protective As soon as the MASTER SW Push Button is set to ON, the BITE of the ECB
shutdowns and continuous monitoring of APU function. starts the Power Up Test. It sends test signals to the different control system
APU continuously monitored functions are: components and sensors and does the analysis of the replies.
S Start sequence and Shutdown sequence incl. automatic shutdown The ECB makes a decision according to the collected data and permits or not
the APU start attempt. If any nonïcritical LRU has failed, it permits the APU
S Speed (N)
start to continue and uses alternate values and schedules. The failed LRUs are
S EGT (Exhaust Gas Temperature) memorized in the BITE fault memory.
S Bleed air supply
NOTE: The POST takes approximately 3 seconds. the APU will start
Power Supply only if it is completed.
The ECB is electrically supplied with 28V DC when the APU MASTER SW In Operation Test
push button is set to ON.
During APU start, operation and shutdown, the BITE of the ECB continuously
An internal TRU (Transformer Rectifier Unit) supplies the ECB circuit with 24V monitors the APU operation limits. It makes sure that the APU operates in a
DC power. The ECB continuously monitors its internal voltages and shuts down preïprogrammed envelope.
the APU in case of DC power loss. When the APU is running, its APU PMG
During an APU start, the BITE of the ECB monitors the APU performance and
supplies the internal TRU maintaining the APU control in case of short
stops it if it leaves the limits. The cause is memorized in the BITE fault
interruption of normal DC power.
memory. According to the type of failed LRU, it permits or not the operation of
BITE APU using alternate values and schedules. When the APU operates outside of
its limits according to the APU configuration and flight phase, the ECB stops
The BITE (Built In Test Equipment) of the ECB makes an analysis of the
the APU. The fault is memorized in the BITE fault memory.
performance of the APU. The readout of this analysis is shown on the MCDU,
through the functions of the CFDS. Self Test
The BITE of the ECB operates in three main modes: The Self Test is initiated from the MCDU APU menus when the APU is not
S Power Up Test mode running. It examines all the internal ECB and external APU circuits. A record of
S In Operation Test mode LRU failures is transmitted to the CFDS.
S Self Test mode. The Self Test is also used to make sure that the system works correctly after a
maintenance action.
The test mode depends on the step of APU operation and which of the LRUs
are examined. NOTE: Do the self test only if APU is not running. It takes also
The BITE memory of the ECB keeps the analysis data which are: approximately 3 seconds.
S the APU life data (containing the serial number of the APU, operating hours
and APU cycles).
S the APU fault data (when an LRU fails the ECB shuts down the APU and
the failed LRU information is kept in the BITE fault memory which is
nonïvolatile).
02|ECB BITE|L2 Page 106

49ï60
MASTER P/BSW POWER UP TEST

SET TO “ON“
TEST
NO SIGNALS
APU PMG
POWER SUPPLY
SHUT DOWN
AND
IN OPERATION LRUS
APU AVAIL TEST
DC POWER TEST
SUPPLY SIGNALS
SUPPLY
NO START SELF TEST
SPEED < 7% AND
MCDU TEST
ACTIVATION ANALYSIS
REPLY APU
SIGNALS
TEST NOT OK
APU OPERATION TEST
OK
DEGRADED NORMAL
FAULT
CFDS MEMORY OR
APU
OPERATION
APU
BITE SHUT DOWN
ECB
Figure 66 ECB Bite Schematic
49ï60
BITE TEST AND FAULT INDICATION

General 1. < LAST LEG REPORT >
By the use of both MCDUs (Multi Function Control and Display Units) in the This gives the LRU failures (class 1 and 2) during the last flight leg, related to
cockpit and the CFDS (Centralized Fault Display System) it is possible to do a the system selection.
Fault analysis and an APU System Test. 2. < PREVIOUS LEG REPORT >
The MCDU shows the APU information in normal mode and menu mode This gives all the LRU failures (class 1 and 2) for the previous flight legs, a
through the CFDS. maximum of 30 failures.
Normal Mode 3. < LRU IDENTIFICATION >
During a normal mode the ECB continuously transmits all class 1 and 2 faults This gives the part and serial number of the ECB only.
and messages to the CFDS. The MCDU display shows the faults and
4. < SYSTEM SELF TEST >
messages when the ”LAST LEG REPORT” is set. The CFDIU creates the
display on the MCDU in a normal mode. This will start a self test and will show any LRU failures (not related to class of
fault).
Menu Mode
5. < APU DATA / OIL >
The menu mode is available on the MCDU display when the ”SYSTEM
REPORT TEST” is set and an “APU“ selection is made. The MCDU display This gives the APU serial number, operation hours, cycles, ECB configuration
shows the related APU system data and the faults when a selection of the APU (TSO or JAR) and the oil level.
menu is made. The ECB makes the display on the MCDU in a menu mode. 6. <SHUT DOWNS>
The APU menu includes the: This gives the cause of the shutdown and the related class 1 LRUs. A list of
S LAST LEG REPORT, the shutdown faults and texts of the possible causes is shown in tables 2, 3
and 5.
S PREVIOUS LEG REPORT,
7. < CLASS 3 FAULTS >
S LRU IDENTIFICATION,
This gives every class 3 fault that has occurred, see table 6. The MCDU
S SYSTEM SELF TEST,
display format changes. The change is related to the mode selection that is
S APU DATA / OIL, made. The text of the LRU failures is related to which LRU has failed. A sample
S SHUT DOWNS, of the LRU failures is given in tables 2, 3, 4 and 6. A flight ”LEG” is specified as
S CLASS 3 FAULTS. from initial power up, through flight, to power off after the aircraft has landed.

Lufthansa Technical Training

49ï60
STEP 1
OR

ENGINE WARNING DISPLAY

MCDU
STATUS PAGE
STEP 2 STEP 3
NEXT

PAGE

Figure 67 ECAM Messages and MCDU MENU

49ï60
STEP 4 B C

A
"
B "!
C #

EXAMPLE 1

!
OR $%
! "

#

EXAMPLE 2
Figure 68 LRU IDENT, Self Test and S/D Reports

49ï60

A
STEP 5 B
NEXT
PAGE

A B

&
& ''# "!
& ""' # "((

& !
# #((
$%

RESULT: NOT OK RESULT: OK
Figure 69 APU Data/Oil and Class 3 Reports

49ï60
STEP 1

!
"!
# ## "(#(

# "("(

STEP 2
NEXT !
PAGE "! $%
( "(#(

# "("(

Figure 70 APU Previous Legs Report

49ï60

CONTROL AND MONITORING APS 3200
49ï60
ELECTRONIC CONTROL BOX COMPONENT DESCRIPTION

FUNCTION OF ECB ECB OUTPUTS
The Electronic Control Box controls and monitors the Auxiliary Power System.
APU Discrete and Analog Outputs
This part lists all the inputs and outputs of the electronic control box.
S Oil system deïoiling valve
ECB INPUTS S Oil level RTD
S GEN scavenge oil filter differential pressure switch
Analog Inputs
S LOP switch
S Generator oil temperature sensor
S Pressure transducers excitation
S Inlet air pressure and temperature sensors
S Inlet Guide Vane LVDT
S EGT sensors
S Bleed Control Valve LVDT
S Rotation speed sensors
S Inlet Guide Vane, Bleed Control Valve and fuel servovalve
S Oil level sensor
S Exciter
S Two oil temperature sensors (ENG oil and GEN oil temperature)
S 3 way solenoid valve.
S Load compressor discharge air pressure sensors
S Load compressor discharge air temperature sensor Aircraft Discrete and Digital Outputs
S Engine ID module (data entry plug) S Backïup start contactor
S Inlet Guide Vane and Bleed Control Valve LVDTs S Main start contactor
S Starter motor voltage sensor S Aircraft relay
S PMG S Bleed control valve open
S APU available
Discrete Inputs
S Start in progress
S APU stop, emergency stop
S Fault
S MES mode
S Flap open and flap closed command
S Air/Ground position
S Aircraft serial communications (ARINC 429, RS 232 C).
S TSO/JAR and A320/A321 configurations
S Load compressor valve activation APU ECB Location
S Start contactor monitor, start command The ECB is installed in the aft Cargo compartment
S Air intake flap open and closed position
S Air intake flap movement
S Low fuel and low oil pressures
S Oil filter bypass
03|ECB|L3 Page 114

49ï60
ANALOG INPUTS TO THE APU

ECB POWER SUPPLY
S GENERATOR OIL TEMPERATURE S OIL SYSTEM (DE-OILING VALVE,
S INLET AIR PRESSURE OIL LEVEL RTD, OIL FILTER AND
S AND TEMPERATURE LOP SWITCHES
S EGT, ROTATION SPEED S PRESSURE TRANSDUCERS EXCITATION
S OIL LEVEL AND TEMPERATURE S LVDTs
S LC DISCHARGE AIR PRESSURE S SERVOVALVES (IGV, BCV, FUEL)
S AND TEMPERATURE S EXCITER
S ENGINE ID E S 3 WAY SOLENOID VALVE
E
S LVDTs C
C
S STARTER MOTOR VOLTAGE B
B
S PMG
O
I
U
N
T
P
DISCRETE INPUTS P TO THE AIRCRAFT
U
U
T
S STOPS (APU, EMERGENCY T S CONTACTORS (BACKUP START,
S
S CONFIGURATIONS (AIR/GROUND), S MAIN START)
TSO/JAR, A320/A321 ECB S AIRCRAFT RELAY
S MES MODE S BCV OPEN
S LC VALVE ACTIVATION S APU AVAILABLE
S STARTS (CONTACTOR MONITOR, S START IN PROGRESS
COMMAND) S FAULT
S AIR INTAKE FLAP POSITIONS S FLAP COMMANDS (OPEN, CLOSED)
(OPEN, CLOSED) S AIRCRAFT SERIAL COMMUNICATIONS
S AIR INTAKE FLAP MOVEMENT
S LOW PRESSURE (OIL, FUEL)
S OIL FILTER BY-PASS
Figure 71 APU ECB Description

03|ECB|L3 Page 115
49ï60
ECB POWER SUPPLY
Main Power Supply
With the APU Master Switch to ON the Main Relay 4KD will be powered from
the aircraft electrical system via 301PP Battery Bus.
Emergency Backup Supply

When The APU is running a PMG (Permanent Magnet Generator) will backup
the ECB power.
The PMG is part of the APU cooling fan.
The PMG sends also a speed signal to the ECB for a backup overspeed
protection (shutdown).
Power Cutoff
The ECB power is cutoff, when the APU is shutdown and the air intake door is
closed, or when the air inlet door fails to close (Door closing process exeeds
30 sec).
03|ECB|L3 Page 116

49ï60
PERMANENT MAGNET
GENERATOR (PMG)
1KD ECB SUPPLY PART OF THE COOLING FAN
301PP
BATTERY
4KD
MAIN RELAY
POWER SUPPLY DC
OR SUPPLY
113S DOOR CLOSURE COMPLETE

POWER
AND OR
14KD K/A SHUT DOWN
110.5S DOOR CLOSE FAILURE
MASTER SWITCH
(DOOR DOES NOT CLOSE
WITH IN 30 SEC)
59KD ECB
Figure 72 ECB Power Supply
03|ECB|L3 Page 117
49ï61
49ï61 CONTROL AND MONITORING

APU START EVENTS FUNCTIONAL OPERATION
APU Master switch- ”ON” ACCELERATION PROCESS
S APU main relay energizes (4KD)
3 % RPM
S Inlet door opens
S 3 way solenoid valve energized
S APU fuel feed pump ”ON” (if pressure < 22PSI)
S Servo valve pulses
S APU fuel low pressure shutoff valve opens
S ECB performs power up test 5 % RPM
S Inlet guide vanes are closed S ECB controls the ”basic” fuel flow to obtain correct ignition in combustion
chamber.
Start switch actuated S Delta EGT > 50 _F initiating acceleration control to 100 % RPM (fuel rate
S Backup start contactor 10KA closes depending on EGT and acceleration).
S 1,5 sec later main Start contactor 5KA closes
55 % RPM
S Starter cranks APU
S Exciter deenergized (Ignition ”OFF”)
S ”ON” light in start P/BSW ”ON”
S Deïoiling solenoid deenergized (closed)
S Inlet guide vanes are closed
S Main start contactor 5KA ”opens”
S Deïoiling valve solenoid energizes (open)
S Starter motor stops
S Exciter energizes (Ignition ”ON”)
S 55 % RPM + 5 sec later: Backup start contactor ”opens”
95 % RPM plus 2 sec
S ON light in start P/BSW ”OFF”
S AVAIL light in start P/BSW ”ON”
S Surge control activated
S Steady state speed control loop activation
100% RPM
S Steady state speed control active to keep constant speed
S Inlet guide vanes are closed until BLEED is switched ”ON”
S EGT control active (achieved by controlling IGV position)
04|CTL&MON|L3 Page 118

49ï61
APU SHUTDOWN EVENTS

COMMANDED SHUTDOWN
S Bleed switched ”OFF”
If bleed was not switched ”OFF” a cool down timer is activated. (120 sec)
S IGV closed
SHUTDOWN
S Fuel Valve (3 Way Solenoid Valve) closes
S 1 sec later Fuel Servo Valve ”Closes”
S EGT and RPM drops
95 % RPM
S AVAIL light in start P/BSW ”OFF”
90 % RPM
S Deïoiling solenoid energized (open)
7 % RPM
S Deïoiling valve deïenergizes (closed)
S Inlet flap closes
S APU main relay deïenergizes
S APU fuel low pressure shut off valve closes and APU fuel feed pump stops.

49ï61
PROTECTIVE AUTO SHUTDOWN OPERATION EMERGENCY SHUTDOWN OPERATION

The ECB initiates an Emergency shutdown when either the APU FIRE
Description
pushbutton located in the cockpit is released out, or when the APU SHUT OFF
When the ECB is electrically supplied, it controls the APU starting and running pushbutton located on the external power receptacle panel is pressed.
phases. If an abnormal parameter is detected, it initiates an immediate
The ECB initiates an automatic emergency shutdown when an APU FIRE is
shutdown without time delay, even if APU bleed air system is used.
detected on ground.
S Main start contactor if failed open
The APU shuts down immediately without time delay, even if the APU bleed air
S Back up start contactor if failed open system is used.
S LOP switch and OIL level RTD failed
S LOP switch and low oil level
S Overspeed/Back up overspeed
S Overtemperature
S Low oil pressure
S High oil temperature
S Failure EGT sensor No1 and No2
S Air intake flap not fully open
S IGV shutïdown
S IGNITION unit
S No flame
S Reverse flow
S No acceleration/low acceleration
S DC power lost
S ECB failure
S Generator high oil temperature
S Loss of speed sensing No I and No 2
S Underspeed
S Generator and gearbox OIL RTDs lost
S Speed sensor No1 and opposite Nïconverter
S Speed sensor No2 and opposite Nïconverter
S 3 way fuel solenoid valve (FCU)
S Fuel servo valve (FCU)
S EGT sensor No1 and opposite EGT converter
S EGT sensor No2 and opposite EGT converter

49ï61

ANALYZERS APS 3200
49ï73
49ï73 ANALYZERS
FAULT TABLES PRESENTATION
NOTE: An (n) at the end of text messages, indicates the number of occurrences (when more than one). Occurrences of four or more are indicated with the
number 4. In normal mode the ATA chapter will be transmitted without hyphens.
Class 1 faults
1st Table: These faults cause the APU to shutdown (or not available)
BITE Detection ATA Chapter Text for CFDS Indication BITE Detection ATA Chapter Text for CFDS Indication
Main Start Contactor 49ï42ï41 CONTACTOR 5KA (n) Speed Sensor No.2 and 49ï71ï13 SPEED SNSR P27 AND
(if failed open) opposite NïConverter ECB 59KD (n)
Backïup Start Contactor 49ï42ï42 CURRENT LIMITER 6KA EGT Sensor No.1 and 49ï72ï15 EGT TC1 P30 AND
(if failed open) OR CONTACTOR 10KA (n) EGT Sensor No.2 EGT TC2 P31 (n)
Main Start Contactor 49ï42ï41 CONTACTOR 5KA or EGT Sensor No.1 and 49ï72ï15 EGT TC1 P30 AND
(if output open or shorted) ECB 59KD (n) opposite EGTïconverter ECB 59KD (n)
B/U Start Contactor 49ï42ï42 CONTACTOR 10KA or EGT Sensor No.2 and 49ï72ï15 EGT TC2 P31 AND
(if output open or shorted) ECB 59KD (n) opposite EGTïconverter ECB 59KD (n)
Low Oil Pressure Switch 49ï94ï14 OIL PRESS SW P14 and Generator and Gearbox 49ï91ï51 OIL TEMP SNSR P25
/oil level RTD failed OIL LEVEL SNSR P8 (n) Oil RTDs AND GENERATOR 8XS (n)
Low Oil Pressure Switch 49ï94ï14 OIL PRESS SW P14 and
and Low Oil Level LOW OIL LEVEL (n)
Air Intake Actuator 49ï16ï51 AIR INTAKE FLAP ACTR
(if inlet door failed in not (n)
fully open position)
Fuel Solenoid 49ï32ï11 FUEL CTL UNIT P19 (n)
Fuel Servo 49ï32ï11 FUEL CTL UNIT P19 (n)
Ignition Unit 49ï41ï38 IGNITION UNIT P10 (n)
ECB 49ï61ï34 ECB 59KD (n)
Speed Sensor No.1 and 49ï71ï13 SPEED SNSRS P26, P27
Speed Sensor No2 (n)
Speed Sensor No.1 and 49ï71ï13 SPEED SNSR P26 AND
opposite NïConverter ECB 59KD (n)
05|ï73|Fault Tables|L2 Page 122

ANALYZERS APS 3200
49ï73
2nd Table: These faults are likely to cause the APU to shutdown 3rd Table: These faults lead to reduced air bleed performance
Overspeed S/D, Primary 49ï32ï11 FUEL CTL UNIT P19 OR Delta P Transducer 49ï51ï19 BLEED FLOW XDCR P24
ECB 59KD (n) (n)
Overspeed S/D, Backup 49ï61ï34 ECB 59KD (n) Bleed Flow Transducer 49ï51ï19 BLEED FLOW XDCR P24
Overtemperature S/D 49ï23ï51 IGV ACTR P21 OR (n)
FUEL CTL UNIT P19 (n) Bleed Control Valve 49ï51ï53 BLEED CTL VLV P33 (n)
Low Oil Pressure S/D 49ï91ï00 CHECK OIL LEAKAGE OR IGV Actuator 49ï23ï53 INLET GUIDE VANE ACTR
OIL PRESS SW P14 (n) P21 (n)
High Oil Temp S/D 49ï52ï51 COOLING FAN/PMG ASSY Failed 10V Pressure 49ï61ï34 ECB 59KD OR
OR OIL COOLER ASSY (n) Excitation APU HARNESS (n)
No Flame S/D 49ï41ï38 IGNITION UNIT P10 OR T LCD Temp. RTD 49ï23ï16 LCDT SENSOR P29 (n)
FUEL CTL UNIT P19 (n)
T Inlet Sensor 49ï23ï17 INLET TEMP/PRESS
No Acceleration S/D 49ï32ï11 FUEL CTL UNIT P19 OR SNSR P22 (n)
(Low Acceleration) DEïOILING SOL P15 (n)
P Inlet Sensor 49ï23ï17 INLET TEMP/PRESS
Reverse Flow S/D 49ï51ï19 BLEED FLOW XDCR P24 SNSR P22 (n)
OR BLEED CONTROL
LC reverse flow detected 49ï51ï19 BLEED FLOW XDCR P24
VALVE P33 (n)
(n)
Generator High Oil 49ï91ï00 CHECK OIL SYSTEM OR
Temperature S/D GENERATOR 8XS (n)
Loss of DC Power – –
Emergency Stop – –
Underspeed S/D 49ï32ï11 FUEL CTL UNIT P19 (n)
No Acceleration S/D 49ï42ï51 STARTER MOTOR 8KA
(Fail to Crank) OR STARTER CLUTCH
ASSY (n)
No Acceleration S/D 49ï32ï11 FUEL CTL UNIT P19 OR
(Deceleration) FUEL FLOW DIVIDER (n)
No APU Connected – –
Overspeed S/D, Backup 49ï52ï51 FAN/PMG ASSY OR
(Fan/PMG Assembly) ECB 59KD (n)

ANALYZERS APS 3200
49ï73
Class 2 faults Class 3 faults
These faults may have consequences if a second fault occurs No shutdowns
Fuel Low Pressure 49ï34ï00 FUEL LOW PRESSURE APU Serial Number 49ï73ï51 SERIAL NUMBER ENCDR
OR LOW FUEL PRESS SW Encoder P20
P17 (n)
ECS Demand Signal 21ï63ï34 NO DATA FROM ECS
Air Intake Actuator 49ï16ï51 AIR INTAKE FLAP ACTR
Failed in Not Fully Closed (n) Incorrect ID Pin Coding 49ï61ï00 WRG ACFT TYPE PIN
Position PROG OR ECB 59KD
ECB 49ï61ï34 ECB 59KD (n) EGT Sensor No.1 49ï72ï15 EGT TC1 P30
Oil Filter 49ï91ï41 OIL FILTER P5 (n) EGT Sensor No.2 49ï72ï15 EGT TC2 P31
(scavenge generator) Speed Sensor No.1 49ï71ï13 SPEED SNSR P26
Fuel Valve Stuck Open 49ï32ï11 FUEL CTL UNIT P19 (n) Speed Sensor No.2 49ï71ï13 SPEED SNSR P27
Low Oil Pressure Switch 49ï94ï14 OIL PRESS SW P14 (n) Gearbox Oil Temp RTD 49ï91ï51 OIL TEMP SNSR P25
Low Oil Level Sensor 49ï93ï17 OIL LEVEL SNSR P8 (n) Generator Oil Temp RTD 24ï23ï51 GENERATOR 8XS
Low Oil Level 49ï93ï00 LOW OIL LEVEL (n) Gearbox Deprime Valve 49ï91ï49 DEïOILING SOL P15
Illogical Flap Actuator 49ï16ï51 AIR INTAKE FLAP ACTR Cold Junction RTD 49ï61ï34 ECB 59KD
Switch Inputs (n)
Low PMG Voltage 49ï52ï53 COOLING FAN/PMG ASSY
APU Low Fuel Pressure 26ï22ï00 FIRE EMERG STOP RLY
Valve Output 6WF
Main Start Contactor 49ï42ï41 CONTACTOR 5KA
Failed Closed
Backup Start Contactor 49ï42ï42 CONTACTOR 10KA
Failed Closed

ANALYZERS APS 3200
49ï73

INDICATING APS 3200
49ï70
49ï70 INDICATING
SYSTEM DESCRIPTION
SPEED SENSORS (2)
General
It is necessary for the APU control system to have a correct speed signal.
Two identical, but separate speed sensors are used. They are located on the
gearbox casing.
A phonic wheel with 24 teeth is attached to the rotor shaft. The gap between
the phonic wheel and the speed sensor is 5 mm and is nonïadjustable.
Electronic Components in the ECB

The two sensors are connected to the ECB which calculates the average value
of the sensors signals.
When the signal difference is greater than 5%, the sensor with the highest
value is selected. This voltage (signal) is sent to an ARINC driver which,
through the ARINC 429 bus, supplies the speed information to the system
page of the ECAM.
Indication
The system page of the ECAM shows the APU speed information.
The ECB 59KD transmits the speed information to the ECAM through the
ARINC 429 Bus as a binary word with Label 176.
The display format has:
S an analog scale from 0 % to 120 % with an amber box at 102 % and with a
RED sector for speeds more than 105 %,
S a digital readout in %
NOTE: A speed signal is also delivered by the PMG (part of the cooling
fan). This speed signal is used by the backïup overspeed
protection 107 %.
13|Iï70|ndicating|L2 Page 126

INDICATING APS 3200
49ï70
SPEED SENSOR
1 2
FRONT BEARING
ECB
MOUNTING
FLANGE
SPEED SENSOR (2) PHONIC WHEEL FRONT BEARING ELECTRICAL PLUG

SUPPORT
GEARBOX LEFT SIDE ECAM (LOWER DISPLAY)
APU SYSTEM PAGE
ROTATION
SPEED
INDICATION
Figure 73 RPM Speed Sensor Description

INDICATING APS 3200
49ï70
THERMOCOUPLES
General
The chromel and alumel type thermocouples provide an electromotive force in
function of the temperature difference between the hot junction in the exhaust
gas stream and the cold junction connected to the measuring device.
The voltage value is approx. one millivolt per 24 _C (75 _F ).
Electronic Components in ECB. The ECB compares the two effects, adjusts
automatically for the cold junction effect and calculates the average EGT value.
An EGT system failure is declared if:
S EGT is lower than 120 _C (250 _F), on an running APU
S EGT is higher than 1200 _C (2200 _F),
If the difference between the thermocouples is higher than 41 _C (105 _F), the
thermocouple with the highest EGT value is selected. As there are two
separate thermocouples, should one fail, the ECB will continue to use the
output of the other.
Indication
The System page of the ECAM shows the APU EGT information. The ECB
59KD transmits the EGT information to the ECAM through the ARINC 429 Bus
as a binary word with label 175.
The display format has:
S a green analog scale which has an amber (advisory) sector and a red
(warning) sector,
S a digital readout in _C.

INDICATING APS 3200
49ï70
THERMOCOUPLE LOCATION
THERMOCOUPLES
ECB
APU LEFT SIDE
THERMOCOUPLE (2)
ELECTRICAL SUPPORT
CONNECTOR SPRING EGT
INDICATION
MOUNTING
FLANGE
ECAM (LOWER DISPLAY)

APU SYSTEM PAGE
Figure 74 EGT Thermocouple Description.
INDICATING APS 3200
49ï70
SERIAL NUMBER ENCODER
General
To associate the engine serial number to all information supplied by the ECB.
The ID (IDentification) module ïSERIAL NUMBER ENCODERï consists of a
printed circuit board which has resistors.
The ECB provides the ID number to the CFDS MCDU display system.
Functional Description
The ID module is made of resistors located on printed circuit board.
The board is housed in an electrical plug and is connected to the ECB by
means of 4 electrical wires.
There are 3 voltage lines VI, V2, V3 and a return line.
The engine ID number is read, validated and stored during the power up phase
of the ECB.
In case of ID module failure, the APU system history data is associated with
the last valid ID number.
If a new valid ID number is available, it is used without erasing the previously
recorded historical data.
Location
The module is installed on the ignition exciter support (APU left side).

INDICATING APS 3200
49ï70
V1
V2
R R R
ENGINE IDENTIFICATION V3 ECB
MODULE
– RETURN
ELECTRICAL DIAGRAM
ELECTRICAL PLUG COVER
RESISTORS
PRINTED
CIRCUIT BOARD
Figure 75 Serial Number Encoder Description

INDICATING APS 3200
49ï70
APU ECAM SYSTEM PAGE DESCRIPTION

AVAIL Indication APU N Indication
Displayed green when APU N is above 95% S APU speed is displayed in green.
S Becomes amber when N > 102 %.
APU BLEED VALVE POSITION S Becomes red when N > 105 %.
S In line
Valve not closed, green. APU EGT Indication
S cross line S APU EGT is displayed in green.
Valve fully closed, green. S Advisory pulses green at 675_C (inhibited during APU start).
S Becomes amber execssive EGT (above 758_ C with APU running)
APU BLEED AIR PRESSURE and (above 1038_ C during APU start).
The relative air pressure is displayed in green. S Becomes red * over temperature (above 798_ C with APU running).
Amber ”XX” replaces the indication when the ADIRS #2 is not available or * EGT max is calculated in the ECB and transmitted to ECAM it is a function
selected OFF. of N during start and a function of ambient temperature when APU is
running.
APU GENERATOR LINE CONTACTOR Indication
LOW OIL LEVEL
Displayed green when the APU GEN line contactor is closed.
This message is displayed pulsing on the ECAM APU page when the APU
APU GEN Parameters MASTER SW is ON and the oil quantity is below the set operation level.
* LOW OIL LEVEL (green) if the quantity becomes lower than 2.6 liter the
Identical with APU GEN parameter on ELEC page.
indication than pulses on the APU page.
FUEL LO PR Indication
Displayed amber in case of APU fuel low pressure detection (Fuel press in
APU fuel feed line is below 16 PSI).
FLAP OPEN Indication

S Displayed green when APU air intake flap is fully open (Master Switch at
ON).
S Advisory if not fully closed 3 mn after Master Switch has been set to OFF.

INDICATING APS 3200
49ï70
4
2
3
5
6
8
9 10
Figure 76 APU ECAM System Display

INDICATING APS 3200
49ï70
ENG WARNING AND STATUS PAGE PRESENTATION
1 APU AVAIL. 4 APU

If APU is running the green ”APU AVAIL” Message will be displayed on the If APU is shown on the STS-page a Class 2 Fault is present. Using the CFDS
MEMO page. If APU Bleed is ”ON” the Message will be ”APU BLEED”. the fault which is stored in the ECB can be identified.
Warnings and Cautions
2 APU Emerg. STOP or APU Auto Shut Down
When the Auxiliary Power Unit operates outside its set limits, the ECB
”APU EMERG STOP” is displayed in case of fire. (Electronic Control Box) shuts down the APU automatically.
”APU AUTO SHUT DOWN” is displayed in case of a FAULT other than a fire. If an Automatic Shutdown occurs, the following cockpit warnings are set.
3 STS
2nd ENG SHUT DOWN

1st ENG TO PWR
800 ft
1st ENG START
1.500 ft
TOUCH DOWN
5mn AFTER
ELEC PWR
LIFT OFF
80 Kts
80 Kts
1 2 3 4 5 6 7 8 9 10
E / WD : FAILURE TITTLE SD FLT

AURAL MASTER AURAL
PAGE PHASE
condition WARNING LIGHT
CALLED WARNING INHIB
AUTO SHUT DOWN SINGL MASTER 3

automatic shut down of APU for a reason E CAUT APU
MASTER 4
other than fire CHIME APU 5
SW
FAULT 7
EMER SHUT DOWN
REPETITIVE MASTER LT 8
fire detection on ground or use of APU shut off CHIME WARN
P/B on interphone panel or APU FIRE P/B pushed
MEMO DISPLAY
APU AVAIL message is displayed in green when the APU N is above 95 %.

Figure 77 ECAM Flight Phases
INDICATING APS 3200
49ï70
2 1
ENGINE WARNING DISPLAY (E/WD)

4
STATUS PAGE (SD)

Figure 78 ECAM Warning and Cautions

INICIAL APU APS_231107_232152

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Airbus

Line and Base Maintenance

ATA 49 AIRBORNE AUXILIARY POWER

49ï00 AIRBORNE AUXILIARY POWER GENERAL

PRIORITY TO ELECTRICAL POWER

GROUND OPERATION LIMIT

SPECIFIC FUEL CONSUMPTION

NOISE LEVEL ï70 ï40 0 15 34 39 55

Figure 1 APU Operating Envelope

Purpose Component Location

AIRCRAFT TAIL CONE

AUXILIARY POWER UNIT (APU)

Figure 2 APU Presentation

APU SYSTEMS INTRODUCTION

BLEED CONTROL VALVE

Figure 3 APU Systems Overview

CONTROL AND INDICATING

Master SW ”Off” (P/B released out)

Figure 4 APU Control Panels

8 APU SHUT OFF PUSH BUTTON

9 APU FIRE LIGHT

Figure 5 APU ECAM SYSTEM DISPLAY

EXTERNAL POWER CONTROL PANEL (108VU)

Figure 6 APU External Controls & Indicating

Figure 7 Safety Precautions

OPERATING ENVELOPE STARTING TIME

APU ROTATION SPEED ELECTRICAL LIMITATION

Figure 8 Operating Limitations

49ï11 POWER PLANT

EQIPM COMP APU COMPARTMENT MUFFLER

APU ACCESS DOOR

Figure 9 APU Installation

APU ACCESS DOOR DESCRIPTION

02|AccDoors OPS|L2 Page 18

The door spring will hold the door in

Figure 11 APU Access Door Opening

Figure 12 Access Door Latches

02|AccDoors OPS|L2 Page 20

APU COMPONENT LOCATION (APU LEFT SIDE)

The load compressor casing which houses the loadcompressor, the

03|Comp LOC|L2 Page 22

5 FUEL CONTROL DE - OILING APU AIR 13

COMPONENT LOCATION (APU RIGHT SIDE)

The AC generator which transforms the mechanical power into electrical

Inlet air pressure and temperature sensor

Load compressor discharge temperature sensor

03|Comp LOC|L2 Page 24

Figure 15 APU Components (Right Side)

49ï12 APU MOUNTS

04|APU Mounts|L2 Page 26

49ï16 AIR INTAKE SYSTEM

AIR INTAKE DUCT

AIR INTAKE FIXED AIR INTAKE

AIR INTAKE FLAP ACTUATOR OPERATION

02|ACT Ops|L3 Page 30

301PP 4KD APU

ECB POWER SUPPLY CLOSING

COMMAND FLAP OPEN

Figure 18 Air Intake Flap Electrical Schematic

AIR INTAKE COMPONENT DESCRIPTION