DOC AIRBUS | AMM A320FAPU Preservation / Storage / Return to Service (131-9(A))
TASK 49-20-00-600-803-A
APU Preservation / Storage / Return to Service (131-9(A))
The preservation procedure of the APU prevents internal and external corrosion and deterioration when the APU is not used. The preservation procedure will give the maximum protection and must be done in clean and dry conditions.
The de-preservation procedure removes preservation materials from the Auxiliary Power Unit (APU) to make the APU serviceable again.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
B. Consumable Materials
C. Work Zones and Access Panels
D. Referenced Information
3. Job Set-up
Subtask 49-20-00-941-061-A ** ON A/C NOT FOR ALL
Subtask 49-20-00-010-076-A ** ON A/C NOT FOR ALL
Subtask 49-20-00-620-062-A ** ON A/C NOT FOR ALL
Subtask 49-20-00-410-087-A ** ON A/C NOT FOR ALL
[Rev.10 from 2021]
2026.04.01 01:28:37 UTC
APU Preservation / Storage / Return to Service (131-9(A))
WARNING:
MAKE SURE THAT YOU HAVE THE CORRECT FIRE FIGHTING EQUIPMENT AVAILABLE.
WARNING:
BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.
WARNING:
PUT THE SAFETY DEVICES AND THE WARNING NOTICES IN POSITION BEFORE YOU START A TASK ON OR NEAR:
- THE FLIGHT CONTROLS
- THE FLIGHT CONTROL SURFACES
- THE LANDING GEAR AND THE RELATED DOORS
- COMPONENTS THAT MOVE.
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: 25m (82ft.) REARWARD OF THE DUCT, MORE THAN 3m (10ft.) ABOVE THE GROUND, AND THE WIDTH OF THE HORIZONTAL STABILIZER
- THE AREA AROUND THE APU AIR-INTAKE: 2m (7ft) AROUND THE INTAKE
- THE AREA OF THE OIL-COOLER OUTLET.
CAUTION:
DO NOT DO AN UNCONTROLLED PRESERVATION IN A SALT AIR ENVIRONMENT. SALT AIR ENVIRONMENT CAN CAUSE CORROSION.
CAUTION:
IF YOU DID NOT DO THE DEPRESERVATION OF THE APU:
- ONLY CLOSE THE CIRCUIT BREAKERS TO DO THE NECESSARY OPERATIONAL TESTS, AND
- OPEN THEM AGAIN AFTER YOU COMPLETE THE OPERATIONAL TESTS.
IF YOU DO NOT OBEY THESE INSTRUCTIONS, AN ACCIDENTAL START OF THE APU CAN OCCUR, WHICH CAN CAUSE DAMAGE TO THE APU.
1. Reason for the JobThe preservation procedure of the APU prevents internal and external corrosion and deterioration when the APU is not used. The preservation procedure will give the maximum protection and must be done in clean and dry conditions.
The de-preservation procedure removes preservation materials from the Auxiliary Power Unit (APU) to make the APU serviceable again.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
| REFERENCE | QTY | DESIGNATION |
|---|---|---|
| No specific | 1 | ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE |
| No specific | AR | COVER - PROTECTION |
| No specific | 1 | INDICATOR-HUMIDITY |
| No specific | AR | SAFETY CLIP - CIRCUIT BREAKER |
| No specific | AR | WARNING NOTICE(S) |
| 98L12003001000 | AR | HARNESS,SAFETY |
| REFERENCE | DESIGNATION |
|---|---|
| (Material No.08BBB1) | Non Aqueous Cleaner-- Petroleum Based - |
| No specific | Desiccant-Silica Gel |
| ZONE/ACCESS | ZONE DESCRIPTION |
|---|---|
| 315 | TAIL CONE APU AND ACCESSORY COMPARTMENT |
| 316 | TAIL CONE APU AND ACCESSORY COMPARTMENT |
| 315AL, 316AR |
| REFERENCE | DESIGNATION |
|---|---|
| TASK 10-11-00-555-013-A | Installation of the Aircraft Protection Equipment |
| TASK 10-11-00-555-014-A | Removal of the Aircraft Protection Equipment |
| TASK 24-23-51-400-001-A | Installation of the APU Generator |
| TASK 24-23-51-400-001-A-01 | Installation of the APU Generator with the Minilift Hoist |
| TASK 24-42-00-861-001-A | Energize the Ground Service Network from the External Power |
| TASK 24-42-00-862-001-A | De-energize the Ground Service Network Supplied from the External Power |
| TASK 28-22-00-710-001-A | Operational Test of the APU Fuel-Pump System on Ground to Purge the Fuel Line |
| TASK 29-00-00-864-001-A | Put the Related Hydraulic System in the Depressurized Configuration before Maintenance Action |
| TASK 49-00-00-100-003-A | Cleaning of the APU Compartment with installed APU (131-9(A)) |
| TASK 49-00-00-550-802-A | Manual Rotation of the APU (131-9(A)) |
| TASK 49-00-00-710-010-A | Operational Test of the APU |
| TASK 49-00-00-860-009-A | APU Shutdown by External Power (131-9(A)) |
| TASK 49-00-00-860-009-A-01 | APU Shutdown by Batteries (131-9(A)) |
| TASK 49-00-00-860-807-A | Dry Motoring of the APU (131-9(A)) |
| TASK 49-00-00-860-809-A | APU No Load Operation (131-9(A)) |
| TASK 49-16-00-100-005-A | Cleaning of the APU Air Intake (131-9(A)) |
| TASK 49-20-00-200-003-A | APU Power Plant Borescope Inspection (131-9(A)) |
| TASK 49-32-41-920-001-A | Replacement of the Fuel Filter (131-9(A)) |
| TASK 49-90-00-600-007-A | Check Oil Level and Replenish (131-9(A)) |
| TASK 49-90-00-600-008-A | Oil Change (Drain Procedure) (131-9(A)) |
| TASK 49-90-00-600-008-A-01 | Oil Change (Top-Off Procedure) (131-9(A)) |
| TASK 49-90-00-600-008-A-02 | Brand/Type Oil Change (Flush Procedure) (131-(A)) |
| TASK 49-91-41-200-002-A | Remove and Discard Oil Filter Elements (131-9(A)) |
| TASK 49-91-42-200-004-A | Inspection of the Metal Chip Detector (131-9(A)) |
| TASK 52-41-00-010-001-A | Open the APU Doors for Access |
| TASK 52-41-00-410-001-A | Close the APU Doors after Access |
Subtask 49-20-00-941-061-A ** ON A/C NOT FOR ALL
A. Safety Precautions
(1) Make sure that the APU fire and overheat detection-system and the APU Fire-Extinguishing system are serviceable.
(2) Follow the Warning related to the Safety Precautions when the APU operates.
(3) Preservation information:
Subtask 49-20-00-860-100-A ** ON A/C NOT FOR ALL (1) Make sure that the APU fire and overheat detection-system and the APU Fire-Extinguishing system are serviceable.
(2) Follow the Warning related to the Safety Precautions when the APU operates.
(3) Preservation information:
| Period/Status | Requirement | Reference |
|---|---|---|
| 0 - 30 DAYS | No preservation required | |
| Up to 3 months | Preserve | Refer to paragraph 4.B. |
| Up to 12 months | Preserve | Refer to paragraph 4.C. |
| Up to 24 months | Preserve | Refer to paragraph 4.D. |
| APU off wing | Follow supplier instructions | - |
| Preservation compromised | Preserve within 5 days | Refer to paragraph 4 |
| Others | Preservation avoidance | Refer to paragraph 4.A. |
B. Aircraft Maintenance Configuration
(1) Energize the ground service network
(Ref. AMM TASK 24-42-00-861-001).
(2) On the overhead panel 25VU, make sure that the APU MASTER SW pushbutton switch is released (ON legend is off).
(3) On the APU section of overhead panel 25VU, put a WARNING NOTICE(S) to tell persons not to start the APU.
(4) Make sure that the hydraulic systems are depressurized
(Ref. AMM TASK 29-00-00-864-001).
Subtask 49-20-00-865-101-A ** ON A/C NOT FOR ALL (1) Energize the ground service network
(Ref. AMM TASK 24-42-00-861-001).
(2) On the overhead panel 25VU, make sure that the APU MASTER SW pushbutton switch is released (ON legend is off).
(3) On the APU section of overhead panel 25VU, put a WARNING NOTICE(S) to tell persons not to start the APU.
(4) Make sure that the hydraulic systems are depressurized
(Ref. AMM TASK 29-00-00-864-001).
WARNING:
BEFORE YOU OPEN THESE CIRCUIT BREAKERS (1QF, 2QF, 3QC), MAKE SURE THAT THE "APU MASTER" SWITCH IS SET TO THE "OFF" POSITION. IF YOU DO NOT DO THIS, THE APU FUEL ISOLATION-VALVE WILL STAY OPEN AND FUEL CAN FLOW OUT. THIS CAN CAUSE A DANGEROUS RISK OF FIRE.
C. Open, safety and tag this(these) circuit breaker(s):| PANEL | DESIGNATION | FIN | LOCATION |
|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||
| 121VU | APU/APU/CTL | 2KD | L42 |
| 121VU | APU/ECB/SPLY | 1KD | L41 |
| 121VU | APU/FUEL/LP VALVE/CTL | 1QF | M40 |
| 121VU | APU/FUEL/LP VALVE/SPLY | 2QF | M39 |
| 121VU | APU/FUEL/PUMP/CTL | 3QC | M38 |
D. Get Access
(2) Put an ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE in position below the APU access doors 315AL and 316AR.
(3) Open APU access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-010-001).
(4) Set the light switch 11LJ to the ON position.
4. ProcedureWARNING:
BEFORE YOU START WORK, YOU MUST PUT ON A SAFETY HARNESS AND ATTACH IT TO THE ACCESS PLATFORM. WITHOUT A SAFETY HARNESS, YOU CAN FALL. THIS CAN KILL YOU OR CAUSE YOU INJURY.
(1) Put on and attach the HARNESS, SAFETY before you start work in the work area.(2) Put an ACCESS PLATFORM 4M (13 FT)-ADJUSTABLE in position below the APU access doors 315AL and 316AR.
(3) Open APU access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-010-001).
(4) Set the light switch 11LJ to the ON position.
Subtask 49-20-00-620-062-A ** ON A/C NOT FOR ALL
A. Conditions in which the preservation of the APU installed on the aircraft is not necessary:
(1) If the aircraft is in this (these) weather condition(s):
(3) It is not necessary to do the APU preservation for two years, if you:
(a) Do the dry-motoring of the APU at intervals of one month (Ref. AMM TASK 49-00-00-860-807).
(4) It is not necessary to do the APU preservation for more than two years, if you:
(a) Do the dry-motoring of the APU at intervals of one month (Ref. AMM TASK 49-00-00-860-807), and
(b) Operate the APU with no load at intervals of one month (Ref. AMM TASK 49-00-00-860-009).
Subtask 49-20-00-620-063-A ** ON A/C NOT FOR ALL (1) If the aircraft is in this (these) weather condition(s):
- Temperature less than 30 DEG.F (-1.11 DEG.C) or more than 125 DEG.F (51.67 DEG.C), and/or
- Humidity more than 40 per cent, and/or
- Salt air.
- Manual rotation of the APU (Ref. AMM TASK 49-00-00-550-802), or
- Dry-motoring of the APU (Ref. AMM TASK 49-00-00-860-807), or
- Operation of the APU with no load (Ref. AMM TASK 49-00-00-860-809).
(3) It is not necessary to do the APU preservation for two years, if you:
(a) Do the dry-motoring of the APU at intervals of one month (Ref. AMM TASK 49-00-00-860-807).
(4) It is not necessary to do the APU preservation for more than two years, if you:
(a) Do the dry-motoring of the APU at intervals of one month (Ref. AMM TASK 49-00-00-860-807), and
(b) Operate the APU with no load at intervals of one month (Ref. AMM TASK 49-00-00-860-009).
B. APU Preservation for Storage during a Maximum of Three Months
(1) Do a general visual inspection of the APU and the APU compartment for oil leaks. No leaks are permitted:
(a) If you find oil leaks:
1 Repair all the oil leaks.
2 Clean the APU externally.
3 Clean the APU compartment (Ref. AMM TASK 49-00-00-100-003).
4 Clean the APU air intake (Ref. AMM TASK 49-16-00-100-005).
(2) Do a general visual inspection of the APU and the APU compartment for fuel leaks. No leaks are permitted:
(a) If you find fuel leaks:
1 Repair all the fuel leaks.
2 Clean the APU externally.
3 Clean the APU compartment (Ref. AMM TASK 49-00-00-100-003).
4 Clean the APU air intake (Ref. AMM TASK 49-16-00-100-005).
(3) Do a general visual inspection of the APU inlet plenum to find Foreign Object Damage (FOD):
(a) If you find FOD:
1 Do a borescope inspection of the APU power plant (Ref. AMM TASK 49-20-00-200-003).
a If you find no damage:
(5) Do not fill the APU reservoir after you drain the oil.
(6) Add desiccant bags:
(8) Clean the engine and the APU compartment:
(a) Clean the engine and the APU compartment from unwanted fuel and oil with Non Aqueous Cleaner-- Petroleum Based - (Material No.08BBB1) .
(9) Attach the COVER - PROTECTION to the air inlets and outlets (Ref. AMM TASK 10-11-00-555-013).
(10) Record in the logbook that the APU preservation procedure is completed.
Subtask 49-20-00-620-064-A ** ON A/C NOT FOR ALL (1) Do a general visual inspection of the APU and the APU compartment for oil leaks. No leaks are permitted:
(a) If you find oil leaks:
1 Repair all the oil leaks.
2 Clean the APU externally.
3 Clean the APU compartment (Ref. AMM TASK 49-00-00-100-003).
4 Clean the APU air intake (Ref. AMM TASK 49-16-00-100-005).
(2) Do a general visual inspection of the APU and the APU compartment for fuel leaks. No leaks are permitted:
(a) If you find fuel leaks:
1 Repair all the fuel leaks.
2 Clean the APU externally.
3 Clean the APU compartment (Ref. AMM TASK 49-00-00-100-003).
4 Clean the APU air intake (Ref. AMM TASK 49-16-00-100-005).
(3) Do a general visual inspection of the APU inlet plenum to find Foreign Object Damage (FOD):
(a) If you find FOD:
1 Do a borescope inspection of the APU power plant (Ref. AMM TASK 49-20-00-200-003).
a If you find no damage:
- Continue the APU preservation procedure.
(5) Do not fill the APU reservoir after you drain the oil.
(6) Add desiccant bags:
CAUTION:
DO NOT PUT THE DESICCANT IN THE BLEED AIR DUCTS. IT CAN CAUSE SMELL IN THE CABIN.
(a) Add one pound (0.454 kg) of Desiccant-Silica Gel to the gas path. NOTE: It is possible to add one pound of desiccant between the air inlet and the exhaust.
(7) Put the WARNING NOTICE(S) in position in the cockpit to tell persons that the APU is not serviceable. (8) Clean the engine and the APU compartment:
(a) Clean the engine and the APU compartment from unwanted fuel and oil with Non Aqueous Cleaner-- Petroleum Based - (Material No.08BBB1) .
(9) Attach the COVER - PROTECTION to the air inlets and outlets (Ref. AMM TASK 10-11-00-555-013).
(10) Record in the logbook that the APU preservation procedure is completed.
C. APU Preservation for Storage during a Maximum 12 Months
(1) Do the steps for the APU preservation storage during a maximum of three months.
(2) Install the sealing caps:
(3) Clean the APU:
(a) Remove all the oil and fuel from the external surface of the APU with Non Aqueous Cleaner-- Petroleum Based - (Material No.08BBB1) .
(4) Attach the WARNING NOTICE(S) in position on the APU to tell persons that preservation procedure for the APU is completed.
(5) Install the INDICATOR-HUMIDITY on the APU. Make sure that you can see the indicator with the APU in the storage position.
(6) Do a check of the humidity indicator every 30 days:
(a) If the relative humidity is less than 40 per cent, no maintenance action is necessary until the next check.
(b) If the relative humidity is more than 40 per cent do a visual inspection of the APU:
Subtask 49-20-00-550-061-A ** ON A/C NOT FOR ALL (1) Do the steps for the APU preservation storage during a maximum of three months.
(2) Install the sealing caps:
CAUTION:
PUT PLASTIC CAPS OR PLUGS ON ALL FUEL AND/OR LUBRICATION SYSTEM COMPONENTS AND LINES. IF YOU USE TAPE, CLOTH, OR METAL CAPS ON THEM, YOU CAN DAMAGE THE APU.
(a) Attach the COVER - PROTECTION to the air inlets and outlets (Ref. AMM TASK 10-11-00-555-013). (3) Clean the APU:
(a) Remove all the oil and fuel from the external surface of the APU with Non Aqueous Cleaner-- Petroleum Based - (Material No.08BBB1) .
(4) Attach the WARNING NOTICE(S) in position on the APU to tell persons that preservation procedure for the APU is completed.
(5) Install the INDICATOR-HUMIDITY on the APU. Make sure that you can see the indicator with the APU in the storage position.
(6) Do a check of the humidity indicator every 30 days:
(a) If the relative humidity is less than 40 per cent, no maintenance action is necessary until the next check.
(b) If the relative humidity is more than 40 per cent do a visual inspection of the APU:
- If you find corrosion, return the APU to a maintenance facility.
- If you find no signs of corrosion, replace the desiccant bags and INDICATOR-HUMIDITY.
D. APU Preservation for Storage Up to 24 Months
(1) Do the steps for the APU preservation storage up to 12 months.
(2) Add one pound (0.454 kg) of Desiccant-Silica Gel to the gas path.
Subtask 49-20-00-550-062-A ** ON A/C NOT FOR ALL (1) Do the steps for the APU preservation storage up to 12 months.
(2) Add one pound (0.454 kg) of Desiccant-Silica Gel to the gas path.
NOTE: The total desiccant quantity will be two pounds (0.908 kg).
NOTE: The desiccant can be added between the air inlet and the exhaust.
E. De-preservation of the Engine
(2) Remove the desiccant and the INDICATOR-HUMIDITY from the gas path.
(3) Make sure that the APU generator is correctly attached (Ref. AMM TASK 24-23-51-400-001).
(4) Do a check of the metal chip detector for unwanted metal (Ref. AMM TASK 49-91-42-200-004).
(5) Do a check of the oil filter elements for contamination, replace if necessary (Ref. AMM TASK 49-91-41-200-002).
(6) Make sure that the oil level is correct (Ref. AMM TASK 49-90-00-600-007).
(7) Do a check of the fuel filter element, replace if necessary (Ref. AMM TASK 49-32-41-920-001).
(8) Purge the APU fuel line (Ref. AMM TASK 28-22-00-710-001).
(9) Do the operational test of the APU (Ref. AMM TASK 49-00-00-710-010). Run the APU for at least five minutes.
(10) Do a check of the APU and the APU connections for fuel, oil and air leaks during operation.
(12) Do the check of the oil filter elements for contamination again, replace if necessary (Ref. AMM TASK 49-91-41-200-002).
(13) Do the check of the fuel filter element, replace if necessary (Ref. AMM TASK 49-32-41-920-001).
(14) Do the check of the oil level (Ref. AMM TASK 49-90-00-600-007).
(15) Record in the log book to show that the APU De-preservation procedure has been done.
(16) Return the serviceable APU to operation.
5. Close-upNOTE: This step is only necessary after APU preservation.
(1) Remove any blanking caps or protective covers (Ref. AMM TASK 10-11-00-555-014). (2) Remove the desiccant and the INDICATOR-HUMIDITY from the gas path.
(3) Make sure that the APU generator is correctly attached (Ref. AMM TASK 24-23-51-400-001).
(4) Do a check of the metal chip detector for unwanted metal (Ref. AMM TASK 49-91-42-200-004).
(5) Do a check of the oil filter elements for contamination, replace if necessary (Ref. AMM TASK 49-91-41-200-002).
(6) Make sure that the oil level is correct (Ref. AMM TASK 49-90-00-600-007).
(7) Do a check of the fuel filter element, replace if necessary (Ref. AMM TASK 49-32-41-920-001).
(8) Purge the APU fuel line (Ref. AMM TASK 28-22-00-710-001).
(9) Do the operational test of the APU (Ref. AMM TASK 49-00-00-710-010). Run the APU for at least five minutes.
(10) Do a check of the APU and the APU connections for fuel, oil and air leaks during operation.
NOTE: Leaks of fuel, oil or air during APU operation are not permitted.
(11) Do the check of the metal chip detector for unwanted metal again (Ref. AMM TASK 49-91-42-200-004). (12) Do the check of the oil filter elements for contamination again, replace if necessary (Ref. AMM TASK 49-91-41-200-002).
(13) Do the check of the fuel filter element, replace if necessary (Ref. AMM TASK 49-32-41-920-001).
(14) Do the check of the oil level (Ref. AMM TASK 49-90-00-600-007).
(15) Record in the log book to show that the APU De-preservation procedure has been done.
(16) Return the serviceable APU to operation.
Subtask 49-20-00-410-087-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) Set the light switch 11LJ to the OFF position.
(3) Close access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-410-001).
(4) Remove the access platform(s).
(5) Remove the safety harness.
Subtask 49-20-00-865-102-A ** ON A/C NOT FOR ALL (1) Make sure that the work area is clean and clear of tools and other items.
(2) Set the light switch 11LJ to the OFF position.
(3) Close access doors 315AL and 316AR (Ref. AMM TASK 52-41-00-410-001).
(4) Remove the access platform(s).
(5) Remove the safety harness.
B. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):
Subtask 49-20-00-860-101-A ** ON A/C NOT FOR ALL | PANEL | DESIGNATION | FIN | LOCATION |
|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||
| 121VU | APU/APU/CTL | 2KD | L42 |
| 121VU | APU/ECB/SPLY | 1KD | L41 |
| 121VU | APU/FUEL/LP VALVE/CTL | 1QF | M40 |
| 121VU | APU/FUEL/LP VALVE/SPLY | 2QF | M39 |
| 121VU | APU/FUEL/PUMP/CTL | 3QC | M38 |
C. Aircraft Maintenance Configuration
(1) De-energize the ground service network
(Ref. AMM TASK 24-42-00-862-001).
(2) Remove the ground support and maintenance equipment, the special and standard tools and all other items.
(3) Remove the WARNING NOTICE(S).
(1) De-energize the ground service network
(Ref. AMM TASK 24-42-00-862-001).
(2) Remove the ground support and maintenance equipment, the special and standard tools and all other items.
(3) Remove the WARNING NOTICE(S).
NOTE: If the APU is not de-preserved do not remove the warning notice.
(4) Put the aircraft back to its initial configuration.