Test of the APU Front-Sealing Buffer-Pressure (APS 3200)

TASK 49-21-00-700-801-A
Test of the APU Front-Sealing Buffer-Pressure (APS 3200)

WARNING: MAKE SURE THAT THE CORRECT FIRE FIGHTING/EXTINGUISHING EQUIPMENT AND THE APPROVED PERSONNEL ARE AVAILABLE. THE APU FIRE EXTINGUISHING SYSTEM IS NOT SUFFICIENT TO EXTINGUISH A FIRE IF ACCESS DOORS 315AL AND 316AR ARE OPEN OR REMOVED.

WARNING: MAKE SURE THAT THE FWD AVIONICS ACCESS DOOR 811 IS OPEN WITH A WARNING PLACARD ATTACHED TO IT. THE WARNING NOTICE MUST TELL PERSONS NOT TO CLOSE THE DOOR. THIS PREVENTS ACCIDENTAL PRESSURIZATION OF THE AIRCRAFT.

WARNING: LOCK THE MECHANISM OF THE ACCESS DOOR 316AR WITH THE PIP PIN WHEN YOU OPEN THE ACCESS DOOR. THIS WILL PREVENT INJURY.

WARNING: DO NOT TOUCH THE APU UNTIL IT IS SUFFICIENTLY COOL TO PREVENT BURNS WHEN YOU DO THE MAINTENANCE TASK(S).

WARNING: WHILE THE APU OPERATES, DO NOT GO INTO THESE AREAS: - THE AREA BEHIND THE APU EXHAUST DUCT: 25 M (82 FT.) REARWARD OF THE DUCT, ABOVE THE GROUND, AND THE WIDTH OF THE HORIZONTAL STABILIZER WITH THE DOORS 315AL AND 316AR IN THEIR OPEN POSITION. - THE AREA AROUND THE APU AIR-INTAKE: 2 M (7 FT.) AROUND THE INTAKE - THE AREA OF THE OIL-COOLER OUTLET. THERE IS A RISK OF INJURY IF YOU GO INTO THESE AREAS WHILE THE APU OPERATES.

WARNING: MAKE SURE THAT ALL PERSONS WHO DO WORK NEAR THE APU USE EAR PROTECTION WHILE THE APU OPERATES. THE LOUD NOISE FROM THE APU CAN CAUSE TEMPORARY OR PERMANENT DAMAGE TO THE EARS.

CAUTION: MAKE SURE THAT THE AREA AROUND THE APU IS CLEAR BEFORE YOU START THE APU. TOOLS, EQUIPMENT AND MATERIALS IN THE APU COMPARTMENT AND/OR ON THE ACCESS PLATFORM CAN CAUSE DAMAGE TO THE APU WHEN IT OPERATES.

CAUTION: BEFORE YOU OPERATE THE APU, MAKE SURE THAT APPROVED PERSONNEL IS AVAILABLE AT MINIMUM ONE APU SHUTDOWN PANEL. THIS IS TO DO AN APU EMERGENCY SHUTDOWN IMMEDIATELY IF AN UNUSUAL MALFUNCTION OCCURS DURING APU OPERATION. IF YOU DO NOT OBEY THIS INSTRUCTION, DAMAGE TO THE EQUIPMENT CAN OCCUR.

CAUTION: DO NOT START OR TRY TO START THE APU MORE THAN THREE TIMES, ONE AFTER THE OTHER. AFTER THE THIRD TIME, THERE MUST BE A MINIMUM OF ONE HOUR BEFORE YOU START OR TRY TO START THE APU AGAIN. THIS MAKES SURE THAT THE TEMPERATURE OF THE STARTER MOTOR DECREASES SUFFICIENTLY.

1. Reason for the Job
This procedure gives the instructions to do an operational test of the APU front-sealing buffer-air to measure the pressure.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	ACCESS PLATFORM 2M (6 FT)
No specific	1	ACCESS PLATFORM 5M (16 FT)- ADJUSTABLE
No specific	AR	CLAMPS
No specific	1	GAGE 5 BAR (75 PSI) - PRESSURE
No specific	1	HOSE LENGTH 5 M (16.4 FT) - FLEXIBLE
No specific	AR	WARNING NOTICE(S)
No specific	Torque wrench: range to between 56 and 51 lbf.in (0.63 and 0.58 m.daN )
No specific	Torque wrench: range to between 150 and 135 lbf.in (1.70 and 1.53 m.daN )

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
315AL, 316AR, 811

C. Expendable Parts

FIG.ITEM	DESIGNATION	IPC-CSN
9	PACKING	AIPC 49-21-04-53-030
9	PACKING	AIPC 49-21-84-20-470

D. Referenced Information

REFERENCE	DESIGNATION
TASK 23-44-00-860-001-A	Operation of the Service Interphone System
TASK 24-41-00-861-002-A	Energize the Aircraft Electrical Circuits from the External Power
TASK 24-41-00-861-002-A-01	Energize the Aircraft Electrical Circuits from the APU
TASK 24-41-00-861-002-A-02	Energize the Aircraft Electrical Circuits from Engine 1(2)
TASK 24-41-00-862-002-A	De-energize the Aircraft Electrical Circuits Supplied from the External Power
TASK 24-41-00-862-002-A-01	De-energize the Aircraft Electrical Circuits Supplied from the APU
TASK 24-41-00-862-002-A-02	De-energize the Aircraft Electrical Circuits Supplied from the Engine 1(2)
TASK 26-22-00-710-001-A	Operational Test of the APU Fire-Extinguishing Loop/Squib
TASK 29-00-00-864-001-A	Put the Related Hydraulic System in the Depressurized Configuration before Maintenance Action
TASK 31-60-00-860-001-A	EIS Start Procedure
TASK 49-11-11-000-003-A	Removal of the Power Plant (APU) (APS 3200)
TASK 49-11-11-400-003-A	Installation of the Power Plant (APU) (APS 3200)
TASK 52-41-00-010-001-A	Open the APU Doors for Access
TASK 52-41-00-010-002-A	Open the Avionics Compartment Doors for Access
TASK 52-41-00-410-001-A	Close the APU Doors after Access
TASK 52-41-00-410-002-A	Close the Avionics Compartment Doors after Access
Location of the APU Forward-Bearing Center-Drain
APU Connections

3. Job Set-up
Subtask 49-21-00-941-050-A ** ON A/C NOT FOR ALL

A. Safety Precautions
(1) Make sure that the fire-fighting/extinguishing equipment is serviceable.
(2) Make sure that the APU fire and overheat detection system and the APU fire-extinguishing system are serviceable (Ref. AMM TASK 26-22-00-710-001).
(3) Make sure that the dangerous areas are clear of persons and/or equipment.
(4) Make sure that the personnel in the cockpit and/or at the APU emergency-shutdown panel, the test personnel and the fire-fighting/extinguishing team can speak to each other.
(5) If necessary, make a service interphone connection from the cockpit to the APU compartment area (Ref. AMM TASK 23-44-00-860-001).
(6) If an emergency or a malfunction occurs during the operation of the APU, do the emergency shutdown procedure immediately. Do this procedure always before you enter the dangerous areas. You can start the emergency shutdown procedure from:

The APU FIRE PUSH pushbutton switch on APU FIRE panel 20VU
The APU SHUT-OFF pushbutton switch on external power panel 108VU.

NOTE: You must be prepared to do the emergency shutdown immediately if fire, smoke, unusual noise, fuel or oil leakage occurs.

Subtask 49-21-00-860-066-A ** ON A/C NOT FOR ALL

B. Aircraft Maintenance Configuration
(1) Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
(2) Depressurize the aircraft hydraulic systems
(Ref. AMM TASK 29-00-00-864-001).
(3) On the AIR COND section of panel 30VU:
(a) Make sure that the APU BLEED pushbutton-switch is in the OFF position (the ON and FAULT legends are off).
(b) Make sure that the X BLEED selector switch is in the AUTO position.
(4) On ENG panel 115VU:
(a) Make sure that the two ENG MASTER control switches are in the OFF position.
(5) Do the EIS start procedure (upper ECAM DU and lower ECAM DU only) (Ref. AMM TASK 31-60-00-860-001).
(a) On the ECAM control panel, push the APU pushbutton switch (on the lower ECAM DU, the APU page comes into view).

Subtask 49-21-00-865-062-A ** ON A/C NOT FOR ALL

C. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	APU/FUEL/BLOW OFF/PUMP	2QC	B14
121VU	APU/FUEL/BLOW OFF/CTL	1QC	K39
121VU	APU/FIRE AND OVHT/DET/LOOP B	2WG	L44
121VU	APU/FIRE AND OVHT/DET/LOOP A	1WG	L43
121VU	APU/APU/CTL	2KD	L42
121VU	APU/ECB/SPLY	1KD	L41
121VU	APU/FIRE/EXTIG/SQUIB/B	2WF	L39
121VU	APU/FIRE/EXTIG/SQUIB/A	1WF	L38
121VU	APU/FIRE/LP VALVE/NORM	4WF	M42
121VU	APU/FIRE/LP VALVE/STBY	3WF	M41
121VU	APU/FUEL/LP VALVE/CTL	1QF	M40
121VU	APU/FUEL/LP VALVE/SPLY	2QF	M39
121VU	APU/FUEL/PUMP/CTL	3QC	M38

Subtask 49-21-00-010-062-A ** ON A/C NOT FOR ALL

D. Get Access
(1) Put an ACCESS PLATFORM 5M (16 FT)- ADJUSTABLE in position at APU access doors 315AL and 316AR.
(2) Open APU access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-010-001).
(3) Set the light switch 11LJ to the ON position.
(4) Remove the APU air intake and exhaust blanking plugs.
(5) Put an ACCESS PLATFORM 2M (6 FT) in position at access door 811.
(6) Open access door 811 (Ref. AMM TASK 52-41-00-010-002).
(a) Put the WARNING NOTICE(S) in position on open access door 811, to tell persons not to close the door.
(7) Remove the ground support equipment, special and standard tools and all other items that are not necessary.

4. Procedure
Subtask 49-21-00-480-050-A ** ON A/C NOT FOR ALL

A. Installation of the Test Equipment
(1) Attach the GAGE 5 BAR (75 PSI) - PRESSURE to the HOSE LENGTH 5 M (16.4 FT) - FLEXIBLE (3) with the CLAMPS (2).
(2) Connect the HOSE LENGTH 5 M (16.4 FT) - FLEXIBLE (3) to the forward bearing center-drain (1) installed at the bottom of the drain mast with the CLAMPS (2).
(3) Carefully pull the HOSE LENGTH 5 M (16.4 FT) - FLEXIBLE (3) below the forward bearing center-drain (1) to make sure that the HOSE LENGTH 5 M (16.4 FT) - FLEXIBLE (3) and the CLAMPS (2) are tight.

Subtask 49-21-00-700-050-A ** ON A/C NOT FOR ALL

B. APU Front-Sealing Buffer-Pressure Test
(1) Operational Test
(a) On the ELEC section of panel 35VU, push the BAT1 and BAT2 pushbutton switches to put them in the AUTO position.
(b) On the AIR COND section of panel 30VU, push the APU BLEED pushbutton switch to put it in the OFF position.
(c) On the AIR COND section of panel 30VU, set the APU X BLEED switch to the AUTO position.
(d) On FUEL control panel 40VU, push the X FEED pushbutton switch to put it in the CLOSED position.
(e) On ECAM control panel 11VU, push the APU pushbutton switch to get the APU systems page.
(f) On the APU section of panel 25VU, push the APU MASTER SW pushbutton switch to put it in the ON position.
(g) When the FLAP OPEN message comes into view on the APU systems page, on panel 25VU, push the APU START pushbutton switch to put it in the ON position.
(h) On the lower ECAM DU, when you get 100 per cent N, on panel 25VU, make sure that:

The ON legend of the START pushbutton switch is off, and
The AVAIL legend of the START pushbutton switch is on.

(i) Operate the APU for five minutes with no load. Measure and record the pressure.
(j) On the APU section of panel 25VU, release the APU MASTER SW pushbutton switch.
(k) On the APU section of panel 25VU, make sure that the ON legend of the APU MASTER SW pushbutton switch and the AVAIL legend of the APU START pushbutton switch go off.
(l) On the lower ECAM DU, make sure that:

The AVAIL indication goes out of view when the AVAIL legend of the APU START pushbutton switch goes off, and
The exhaust gas temperature and N indicators go off when the electronic control box is de-energized.

(m) Wait for two minutes after the AVAIL legend goes off then put the BAT 1 and BAT 2 pushbutton switches in the OFF position.

NOTE: This gives sufficient time for the air intake to fully close.

(2) If the pressure measured at the forward bearing center-drain (1) is more than 4 psi (0.276 bar), it is sufficient. Do the test again after an interval of 600 flight hours.
(3) If the pressure measured at the forward bearing center-drain (1) is less than 4 psi (0.276 bar):
(a) Carefully pull the HOSE LENGTH 5 M (16.4 FT) - FLEXIBLE (3) below the forward bearing center-drain (1) to make sure that the HOSE LENGTH 5 M (16.4 FT) - FLEXIBLE (3) and the CLAMPS (2) stayed tight during the operational test.
(b) Make sure that there are no signs of loose b-nuts or connectors in the connections that follow:
1 Make sure that the nuts (4), (5) and (6) are tight:
a If there are signs of loose nuts, TORQUE the nuts (4), (5) and (6) to between 150 and 135 lbf.in (1.70 and 1.53 m.daN )

.
2 Make sure that the bolts (7), (8) and (10) are tight:
a If there are signs of loose bolts, TORQUE the bolts (7), (8) and (10) to between 56 and 51 lbf.in (0.63 and 0.58 m.daN )

.
(4) If there are no loose b-nuts or connections, do the steps that follow:
(a) Remove the bolts (10) and disconnect the tube (11).
(b) Remove and discard the packing (9).
(c) Install the new AIPC 49-21-04-53-030 PACKING (9) or the new AIPC 49-21-84-20-470 PACKING (9).
(d) Install the bolts (10).
(e) TORQUE the bolts (10) to between 56 and 51 lbf.in (0.63 and 0.58 m.daN )

.
(5) Do the pressure test again:
(a) If the pressure measured at the forward bearing center-drain (1) is more than 4 psi (0.276 bar), it is sufficient. Do the test again after an interval of 600 flight hours.
(b) If the pressure measured at the forward bearing center-drain (1) is between 1 psi (0.069 bar) and 4 psi (0.276 bar), do the test again after an interval of 200 flight hours. You can extend this interval if the pressure indications are stable in time.
(c) If the pressure measured at the forward bearing center-drain (1) continues to be less than 1 psi (0.069 bar), replace the APU at the next check (Ref. AMM TASK 49-11-11-000-003) and (Ref. AMM TASK 49-11-11-400-003).
(6) Carefully pull the HOSE LENGTH 5 M (16.4 FT) - FLEXIBLE (3) below the forward bearing center-drain (1) to make sure that the HOSE LENGTH 5 M (16.4 FT) - FLEXIBLE (3) and the CLAMPS (2) stayed tight during the operational test.
(a) If there are signs of loose b-nuts or connections, the pressure measured can change. Do the steps 4.B.(3)(b), and 4.B.(5) again.

Subtask 49-21-00-080-050-A ** ON A/C NOT FOR ALL

C. Removal of the Test Equipment
(1) Loosen the CLAMPS (2).
(2) Disconnect the HOSE LENGTH 5 M (16.4 FT) - FLEXIBLE (3) from the forward bearing center-drain (1).

5. Close-up
Subtask 49-21-00-410-062-A ** ON A/C NOT FOR ALL

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Remove the WARNING NOTICE(S).
(3) Close access door 811 (Ref. AMM TASK 52-41-00-410-002).
(4) Install the APU air intake and exhaust blanking plugs.
(5) Set the light switch 11LJ to the OFF position.
(6) Close APU access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-410-001).
(7) Remove the access platform(s).

Subtask 49-21-00-860-067-A ** ON A/C NOT FOR ALL

B. Aircraft Maintenance Configuration
(1) Put the related hydraulic system in the pressurized configuration (Ref. AMM TASK 29-00-00-864-001).
(2) De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).
(3) Put the aircraft back to its initial configuration.

[Rev.10 from 2021] 2026.04.01 01:28:54 UTC