DOC AIRBUS | AMM A320FInstallation of the Hydraulic Control Unit (HCU) Pressure Switch [PW11]
TASK 78-31-21-400-801-A
Installation of the Hydraulic Control Unit (HCU) Pressure Switch
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
B. Consumable Materials
C. Work Zones and Access Panels
D. Expendable Parts
E. Referenced Information
3. Job Set-up
Subtask 78-31-21-941-056-A ** ON A/C NOT FOR ALL
Subtask 78-31-21-420-050-A ** ON A/C NOT FOR ALL
Subtask 78-31-21-410-050-A ** ON A/C NOT FOR ALL
[Rev.10 from 2021]
2026.04.01 03:31:26 UTC
Installation of the Hydraulic Control Unit (HCU) Pressure Switch
WARNING:
BE CAREFUL WHEN YOU DO WORK ON THE ENGINE AFTER SHUTDOWN. THE ENGINE CAN STAY HOT FOR A LONG TIME. IF YOU DO NOT OBEY THIS INSTRUCTION, INJURY CAN OCCUR.
WARNING:
WEAR APPLICABLE PERSONAL PROTECTIVE EQUIPMENT (PPE) WHEN YOU DO THIS TASK. BEFORE YOU USE PPE, READ, UNDERSTAND AND OBEY ALL INSTRUCTIONS FOR ITS USE. THESE INSTRUCTIONS INCLUDE INSTRUCTIONS FROM THE MANUFACTURER, YOUR EMPLOYER AND GOVERNMENT REGULATIONS. YOU CAN GET INJURED IF YOU DO NOT USE PPE. GET INSTRUCTIONS FROM YOUR EMPLOYER ON WHICH PPE IS NECESSARY.
ZONE: 400
FIN: 102EG1 ** ON A/C NOT FOR ALL
FIN: 102EG2 ** ON A/C NOT FOR ALL
FIN: 103EG1 ** ON A/C NOT FOR ALL
FIN: 103EG2 ** ON A/C NOT FOR ALL
1. Reason for the JobFIN: 102EG1 ** ON A/C NOT FOR ALL
FIN: 102EG2 ** ON A/C NOT FOR ALL
FIN: 103EG1 ** ON A/C NOT FOR ALL
FIN: 103EG2 ** ON A/C NOT FOR ALL
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
| REFERENCE | QTY | DESIGNATION |
|---|---|---|
| No specific | 1 | ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE |
| No specific | AR | COVER - PROTECTION |
| No specific | 1 | PLIERS - JAWED, SOFT |
| No specific | AR | WARNING NOTICE(S) |
| No specific | Torque wrench: range to between 39.00 and 31.92 lbf.in (0.44 and 0.36 m.daN )  | |
| No specific | Torque wrench: range to between 125.64 and 102.72 lbf.in (1.42 and 1.16 m.daN ) | |
| A701191 | 1 | HCU PROX. SENSOR INSTALL |
| A708405 | 1 | PROX SENSOR R/I TOOL |
| REFERENCE | DESIGNATION |
|---|---|
| (Material No.PU5-0007) | A-A-59313 anti-seize compound, zinc dust petrolatum |
| ZONE/ACCESS | ZONE DESCRIPTION |
|---|---|
| 400 | POWER PLANT, NACELLES AND PYLONS |
| FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1) | |
| 413AT | |
| FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2) | |
| 423AT | |
| FIG.ITEM | DESIGNATION | IPC-CSN |
|---|---|---|
| 4 | WASHER | AIPC 78-31-86-10-030 |
| REFERENCE | DESIGNATION |
|---|---|
| TASK 54-52-11-000-805-A | Removal of the Access Skin Panels |
| TASK 54-52-11-400-805-A | Installation of the Access Skin Panels |
| TASK 71-00-00-860-832-A | Procedure to Prevent Engine Motoring and to Stop the Electrical Supply to the EEC |
| TASK 73-25-34-400-802-A | Installation of the Engine Interface Unit (EIU) |
| TASK 78-30-00-040-805-A | Deactivation of the Thrust Reverser System for Ground Maintenance |
| TASK 78-30-00-440-805-A | Reactivation of the Thrust Reverser System after Ground Maintenance |
| TASK 78-31-00-710-805-A | Operational Test of Thrust Reverser with MCDU |
| TASK 78-31-00-710-805-A-01 | Thrust Reverser Cycling Test (Engine Running) |
| FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1) | |
| TASK 29-10-00-864-001-A | Depressurize the Green Hydraulic System |
| TASK 29-14-00-614-001-A | Depressurization of the Hydraulic Reservoirs |
| TASK 29-14-00-614-002-A | Pressurization of the Hydraulic Reservoirs through the Ground Connector |
| TASK 29-14-00-614-002-A-01 | Pressurization of the Hydraulic Reservoirs with the Auxiliary Power Unit (APU) |
| FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2) | |
| TASK 29-10-00-864-002-A | Depressurize the Yellow Hydraulic System |
| TASK 29-14-00-614-001-A | Depressurization of the Hydraulic Reservoirs |
| TASK 29-14-00-614-002-A | Pressurization of the Hydraulic Reservoirs through the Ground Connector |
| TASK 29-14-00-614-002-A-01 | Pressurization of the Hydraulic Reservoirs with the Auxiliary Power Unit (APU) |
Hydraulic Control Unit (HCU) Pressure SwitchSubtask 78-31-21-941-056-A ** ON A/C NOT FOR ALL
A. Safety Precautions
(1) Make sure that you did the procedure to prevent engine motoring and to stop the electrical supply to the Electronic Engine Control (EEC)
(Ref. AMM TASK 71-00-00-860-832)
Subtask 78-31-21-864-051-A ** ON A/C NOT FOR ALL (1) Make sure that you did the procedure to prevent engine motoring and to stop the electrical supply to the Electronic Engine Control (EEC)
(Ref. AMM TASK 71-00-00-860-832)
B. Depressurization of the Aircraft Hydraulic Systems
(1) Make sure that the WARNING NOTICE(S) is in position to tell persons not to pressurize the applicable system.
(a) On the HYD/FUEL panel 40VU of the overhead panel
(b) On the ground service panel of the applicable hydraulic system.
(2) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
(a) Make sure that the Green hydraulic system is depressurized (Ref. AMM TASK 29-10-00-864-001).
(b) Make sure that the reservoir of the Green hydraulic system is depressurized (Ref. AMM TASK 29-14-00-614-001).
(3) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
(a) Make sure that the Yellow hydraulic system is depressurized (Ref. AMM TASK 29-10-00-864-002).
(b) Make sure that the reservoir of the Yellow hydraulic system is depressurized (Ref. AMM TASK 29-14-00-614-001).
Subtask 78-31-21-865-051-A ** ON A/C NOT FOR ALL (1) Make sure that the WARNING NOTICE(S) is in position to tell persons not to pressurize the applicable system.
(a) On the HYD/FUEL panel 40VU of the overhead panel
(b) On the ground service panel of the applicable hydraulic system.
(2) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
(a) Make sure that the Green hydraulic system is depressurized (Ref. AMM TASK 29-10-00-864-001).
(b) Make sure that the reservoir of the Green hydraulic system is depressurized (Ref. AMM TASK 29-14-00-614-001).
(3) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
(a) Make sure that the Yellow hydraulic system is depressurized (Ref. AMM TASK 29-10-00-864-002).
(b) Make sure that the reservoir of the Yellow hydraulic system is depressurized (Ref. AMM TASK 29-14-00-614-001).
C. Make sure that this(these) circuit breaker(s) is(are) open, safetied and tagged:
Subtask 78-31-21-040-051-A ** ON A/C NOT FOR ALL | PANEL | DESIGNATION | FIN | LOCATION |
|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||
| FOR FIN: 4020KM1 (POWER PLANTDEMOUNTABLE, ENG 1) | |||
| 121VU | ENG1/REV/LOCK | 1EG1 | N44 |
| 121VU | ICU A/ENG1 PWR SUPPLY | 22KS1 | R39 |
| ** ON A/C NOT FOR ALL | |||
| 121VU | ICU B/ENG1 PWR SUPPLY | 101KS1 | R42 |
| ** ON A/C NOT FOR ALL | |||
| 121VU | ENG1/REV/LOCK | 1EG1 | R44 |
| 121VU | ICU A/ENG1 PWR SUPPLY | 22KS1 | R38 |
| ** ON A/C NOT FOR ALL | |||
| FOR FIN: 4020KM2 (POWER PLANTDEMOUNTABLE, ENG 2) | |||
| 121VU | ENG2/REV/LOCK | 1EG2 | N45 |
| 121VU | ICU A/ENG2 PWR SUPPLY | 22KS2 | R40 |
| ** ON A/C NOT FOR ALL | |||
| 121VU | ICU B/ENG2 PWR SUPPLY | 101KS2 | R43 |
| ** ON A/C NOT FOR ALL | |||
| 121VU | ENG2/REV/LOCK | 1EG2 | R45 |
| 121VU | ICU A/ENG2 PWR SUPPLY | 22KS2 | R39 |
D. Deactivation of the Thrust Reverser System for Maintenance
Subtask 78-31-21-010-051-A ** ON A/C NOT FOR ALL WARNING:
YOU MUST DEACTIVATE THE THRUST REVERSER BEFORE YOU DO WORK ON OR AROUND IT. IF YOU DO NOT, THE THRUST REVERSER CAN OPERATE ACCIDENTALLY AND CAUSE AN INJURY AND/OR DAMAGE.
(1) Make sure that you did the deactivation of the thrust reverser system for maintenance (Ref. AMM TASK 78-30-00-040-805). E. Get Access
(1) Make sure that the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE is in position.
(2) Make sure that the pylon access panel is removed (Ref. AMM TASK 54-52-11-000-805):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
413AT
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
423AT
4. Procedure(1) Make sure that the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE is in position.
(2) Make sure that the pylon access panel is removed (Ref. AMM TASK 54-52-11-000-805):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
413AT
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
423AT
Subtask 78-31-21-420-050-A ** ON A/C NOT FOR ALL
A. Installation of the Hydraulic Control Unit (HCU) pressure switch
(1) Removal of the protection covers:
(2) Install the HCU pressure switches (102EG) (2) and (103EG) (3) and the switch plate on the HCU.
(3) Put the two HCU pressure switches (2) and (3) on the switch plate.
(4) Make sure that the master keyways of the two HCU pressure switches (2) and (3) are in the correct position.
(5) Install the two new AIPC 78-31-86-10-030 WASHER (4).
(6)PU5-0007 A-A-59313 anti-seize compound, zinc dust petrolatum
(8) Install the two lock nuts (5).
(9) Hold the HCU pressure switches (2) and (3) in position with the A708405 PROX SENSOR R/I TOOL.
(10) Torque the two lock nuts (5) to between 125.64 and 102.72 lbf.in (1.42 and 1.16 m.daN ).
(11) Examine the position of the lock nuts (5) in relation to the tabs of the tab washers (4).
(12) (13) If necessary, tighten the lock nuts (5) more to adjust the position of the lock nuts (5). Do not loosen the lock nuts (5) to get the correct position.
(14) Install the HCU pressure switches (2) and (3) and the switch plate on the HCU with the four bolts (1).
(15) TORQUE the bolts (1) to between 39.00 and 31.92 lbf.in (0.44 and 0.36 m.daN ).
(18) Examine the installation of the tab washers (4). Make sure that:
(20) Connect the CH B DCU proximity sensor harness to the HCU pressure switch (103EG) (3).
(21) Tighten the connector with your fingers. Then, tighten the connector 1/8 to 1/4 of a turn more with a PLIERS - JAWED, SOFT.
(22) Connect the CH A DCU proximity sensor harness to the HCU pressure switch (102EG) (2).
(23) Tighten the connector with your fingers. Then, tighten the connector 1/8 to 1/4 of a turn more with a PLIERS - JAWED, SOFT.
(24) Connect the ICU coil harness to the HCU.
(25) Tighten the connector with your fingers. Then, tighten the connector 1/8 to 1/4 of a turn more with a PLIERS - JAWED, SOFT.
5. Close-up(1) Removal of the protection covers:
CAUTION:
REMOVE THE PROTECTION COVERS FROM THE OPENINGS AS NECESSARY TO PREVENT ENGINE DAMAGE.
(a) Make sure that you remove all the necessary COVER - PROTECTION to prevent damage to the engine. (2) Install the HCU pressure switches (102EG) (2) and (103EG) (3) and the switch plate on the HCU.
(3) Put the two HCU pressure switches (2) and (3) on the switch plate.
(4) Make sure that the master keyways of the two HCU pressure switches (2) and (3) are in the correct position.
(5) Install the two new AIPC 78-31-86-10-030 WASHER (4).
(6)
WARNING:
BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.
(7) Apply the (8) Install the two lock nuts (5).
(9) Hold the HCU pressure switches (2) and (3) in position with the A708405 PROX SENSOR R/I TOOL.
(10) Torque the two lock nuts (5) to between 125.64 and 102.72 lbf.in (1.42 and 1.16 m.daN )
. (11) Examine the position of the lock nuts (5) in relation to the tabs of the tab washers (4).
(12) (13) If necessary, tighten the lock nuts (5) more to adjust the position of the lock nuts (5). Do not loosen the lock nuts (5) to get the correct position.
(14) Install the HCU pressure switches (2) and (3) and the switch plate on the HCU with the four bolts (1).
(15) TORQUE the bolts (1) to between 39.00 and 31.92 lbf.in (0.44 and 0.36 m.daN )
. NOTE: Make sure the breakaway torque for the bolts (1) is at least 2.0 lbf.in (0.023 m.daN).
(16) (17) Bend the tab washers (4) with the A701191 HCU PROX. SENSOR INSTALL to safety the two lock nuts (5). (18) Examine the installation of the tab washers (4). Make sure that:
- The location tab is in the location tab hole.
- The anti-rotation tabs are bent and flush against the flat side of the lock nuts (5).
- The anti-rotation tabs prevent the rotation of the lock nuts (5).
- There are no sharp corners, nicks, or cracks at the bend of the anti-rotation tabs.
- There is no damage to surfaces or protective treatment of the lock nuts (5) or mating components.
(20) Connect the CH B DCU proximity sensor harness to the HCU pressure switch (103EG) (3).
(21) Tighten the connector with your fingers. Then, tighten the connector 1/8 to 1/4 of a turn more with a PLIERS - JAWED, SOFT.
(22) Connect the CH A DCU proximity sensor harness to the HCU pressure switch (102EG) (2).
(23) Tighten the connector with your fingers. Then, tighten the connector 1/8 to 1/4 of a turn more with a PLIERS - JAWED, SOFT.
(24) Connect the ICU coil harness to the HCU.
(25) Tighten the connector with your fingers. Then, tighten the connector 1/8 to 1/4 of a turn more with a PLIERS - JAWED, SOFT.
Subtask 78-31-21-410-050-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) Install the access panel on the pylon (Ref. AMM TASK 54-52-11-400-805):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
413AT
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
423AT
Subtask 78-31-21-440-050-A ** ON A/C NOT FOR ALL (1) Make sure that the work area is clean and clear of tools and other items.
(2) Install the access panel on the pylon (Ref. AMM TASK 54-52-11-400-805):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
413AT
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
423AT
B. Do the reactivation of the thrust reverser system after maintenance (Ref. AMM TASK 78-30-00-440-805).
Subtask 78-31-21-865-052-A ** ON A/C NOT FOR ALL C. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):
Subtask 78-31-21-863-050-A ** ON A/C NOT FOR ALL | PANEL | DESIGNATION | FIN | LOCATION |
|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||
| FOR FIN: 1000EM1 (ENGINE1) | |||
| 121VU | ENG1/REV/LOCK | 1EG1 | N44 |
| 121VU | ICU A/ENG1 PWR SUPPLY | 22KS1 | R39 |
| ** ON A/C NOT FOR ALL | |||
| 121VU | ICU B/ENG1 PWR SUPPLY | 101KS1 | R42 |
| ** ON A/C NOT FOR ALL | |||
| 121VU | ENG1/REV/LOCK | 1EG1 | R44 |
| 121VU | ICU A/ENG1 PWR SUPPLY | 22KS1 | R38 |
| ** ON A/C NOT FOR ALL | |||
| FOR FIN: 1000EM2 (ENGINE2) | |||
| 121VU | ENG2/REV/LOCK | 1EG2 | N45 |
| 121VU | ICU A/ENG2 PWR SUPPLY | 22KS2 | R40 |
| ** ON A/C NOT FOR ALL | |||
| 121VU | ICU B/ENG2 PWR SUPPLY | 101KS2 | R43 |
| ** ON A/C NOT FOR ALL | |||
| 121VU | ENG2/REV/LOCK | 1EG2 | R45 |
| 121VU | ICU A/ENG2 PWR SUPPLY | 22KS2 | R39 |
D. Pressurization of the Aircraft Hydraulic Systems
(1) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
(a) Pressurize the reservoir of the Green hydraulic system (Ref. AMM TASK 29-14-00-614-002).
(2) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
(a) Pressurize the reservoir of the Yellow hydraulic system (Ref. AMM TASK 29-14-00-614-002).
Subtask 78-31-21-942-050-A ** ON A/C NOT FOR ALL (1) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
(a) Pressurize the reservoir of the Green hydraulic system (Ref. AMM TASK 29-14-00-614-002).
(2) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
(a) Pressurize the reservoir of the Yellow hydraulic system (Ref. AMM TASK 29-14-00-614-002).
E. Put the aircraft back to its initial configuration.
(1) Remove the access platform(s).
(2) Remove the WARNING NOTICE(S).
Subtask 78-31-21-710-050-A ** ON A/C NOT FOR ALL (1) Remove the access platform(s).
(2) Remove the WARNING NOTICE(S).
F. Test
(1) Make sure that all the circuit breakers shown in the paragraph Procedure of the engine interface unit installation are closed. If they are not, close them in the recommended sequence
(Ref. AMM TASK 73-25-34-400-802)
(2) Do the operational test of the thrust reverser with MCDU (Ref. AMM TASK 78-31-00-710-805).
(1) Make sure that all the circuit breakers shown in the paragraph Procedure of the engine interface unit installation are closed. If they are not, close them in the recommended sequence
(Ref. AMM TASK 73-25-34-400-802)
(2) Do the operational test of the thrust reverser with MCDU (Ref. AMM TASK 78-31-00-710-805).