DOC AIRBUS | AMM A320FRemoval of the Hydraulic Control Unit (HCU) Pressure Switch [PW11]
TASK 78-31-21-000-801-A
Removal of the Hydraulic Control Unit (HCU) Pressure Switch
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment
B. Work Zones and Access Panels
C. Referenced Information
3. Job Set-up
Subtask 78-31-21-941-050-A ** ON A/C NOT FOR ALL
Subtask 78-31-21-020-050-A ** ON A/C NOT FOR ALL
[Rev.10 from 2021]
2026.04.01 03:31:25 UTC
Removal 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.
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 | 1 | CAP - PROTECTION |
| No specific | 1 | COVER - PROTECTION |
| No specific | AR | SAFETY CLIP - CIRCUIT BREAKER |
| No specific | AR | WARNING NOTICE(S) |
| A701191 | 1 | HCU PROX. SENSOR INSTALL |
| A708405 | 1 | PROX SENSOR R/I TOOL |
| 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 | |
| REFERENCE | DESIGNATION |
|---|---|
| TASK 54-52-11-000-805-A | Removal 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 78-30-00-040-805-A | Deactivation of the Thrust Reverser System for Ground Maintenance |
| 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 |
| 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 |
Hydraulic Control Unit (HCU) Pressure SwitchSubtask 78-31-21-941-050-A ** ON A/C NOT FOR ALL
A. Safety Precautions
(1) Do 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 78-31-21-864-050-A ** ON A/C NOT FOR ALL (1) Do 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 Hydraulic System
(1) Put a WARNING NOTICE(S) 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) Depressurize the Green hydraulic system (Ref. AMM TASK 29-10-00-864-001).
(b) Depressurize the reservoir of the Green hydraulic system (Ref. AMM TASK 29-14-00-614-001).
(3) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
(a) Depressurize the Yellow hydraulic system (Ref. AMM TASK 29-10-00-864-002).
(b) Depressurize the reservoir of the Yellow hydraulic system (Ref. AMM TASK 29-14-00-614-001).
Subtask 78-31-21-865-050-A ** ON A/C NOT FOR ALL (1) Put a WARNING NOTICE(S) 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) Depressurize the Green hydraulic system (Ref. AMM TASK 29-10-00-864-001).
(b) Depressurize the reservoir of the Green hydraulic system (Ref. AMM TASK 29-14-00-614-001).
(3) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
(a) Depressurize the Yellow hydraulic system (Ref. AMM TASK 29-10-00-864-002).
(b) Depressurize the reservoir of the Yellow hydraulic system (Ref. AMM TASK 29-14-00-614-001).
C. Open, safety and tag this(these) circuit breaker(s):
Subtask 78-31-21-040-050-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 for Maintenance
Subtask 78-31-21-010-050-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) Do the deactivation of the thrust reverser system for maintenance (Ref. AMM TASK 78-30-00-040-805). E. Get Access
(1) Put an ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position.
(2) Remove the access panel on the pylon to get access to the HCU (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) Put an ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position.
(2) Remove the access panel on the pylon to get access to the HCU (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 78-31-21-020-050-A ** ON A/C NOT FOR ALL
A. Removal of the Hydraulic Control Unit (HCU) pressure switch:
(1) Disconnect the ICU coil harness from the HCU.
(2) Put CAP - PROTECTION on the harness and the connector on the HCU.
(3) Disconnect the CH A DCU proximity sensor harness from HCU pressure switch (102EG) (2).
(4) Put CAP - PROTECTION on the harness and the HCU pressure switch (2).
(5) Disconnect the CH B DCU proximity sensor harness from HCU pressure switch (103EG) (3).
(6) Put CAP - PROTECTION on the harness and the HCU pressure switch (3).
(7) Remove the four bolts (1) that attach the switch plate and HCU pressure switches (2) and (3) to the HCU.
(8) Remove the HCU pressure switches (2) and (3) from the switch plate.
(a) Bend the tab washers (4) with the A701191 HCU PROX. SENSOR INSTALL to unlock the two nuts (5).
(b) Carefully, remove the two nuts (5) and two tab washers (4) from the two HCU pressure switches (2) and (3) with the A708405 PROX SENSOR R/I TOOL.
(c) Remove the HCU pressure switches (2) and (3) from the switch plate.
(9) Installation of the protection covers
(1) Disconnect the ICU coil harness from the HCU.
(2) Put CAP - PROTECTION on the harness and the connector on the HCU.
(3) Disconnect the CH A DCU proximity sensor harness from HCU pressure switch (102EG) (2).
(4) Put CAP - PROTECTION on the harness and the HCU pressure switch (2).
(5) Disconnect the CH B DCU proximity sensor harness from HCU pressure switch (103EG) (3).
(6) Put CAP - PROTECTION on the harness and the HCU pressure switch (3).
(7) Remove the four bolts (1) that attach the switch plate and HCU pressure switches (2) and (3) to the HCU.
(8) Remove the HCU pressure switches (2) and (3) from the switch plate.
(a) Bend the tab washers (4) with the A701191 HCU PROX. SENSOR INSTALL to unlock the two nuts (5).
(b) Carefully, remove the two nuts (5) and two tab washers (4) from the two HCU pressure switches (2) and (3) with the A708405 PROX SENSOR R/I TOOL.
(c) Remove the HCU pressure switches (2) and (3) from the switch plate.
(9) Installation of the protection covers
CAUTION:
INSTALL PROTECTION COVERS ON ALL THE OPENINGS IMMEDIATELY TO PREVENT DAMAGE TO THE ENGINE.
(a) Make sure that you install COVER - PROTECTION on the harness connectors, HCU connectors, and HCU pressure switches (2) and (3) to prevent damage to the engine.