Removal of the Hydraulic Control Unit (HCU) Proximity Sensor [PW11]

TASK 78-31-22-000-801-A
Removal of the Hydraulic Control Unit (HCU) Proximity Sensor

WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE AND THE ADJACENT COMPONENTS AFTER ENGINE SHUTDOWN. THE ENGINE, THE ENGINE OIL AND THE ADJACENT COMPONENTS CAN STAY HOT FOR A LONG TIME. IF YOU DO NOT OBEY THIS INSTRUCTION, INJURY CAN OCCUR.

ZONE: 400
FIN: 100EG1 ** ON A/C NOT FOR ALL
FIN: 100EG2 ** ON A/C NOT FOR ALL
FIN: 101EG1 ** ON A/C NOT FOR ALL
FIN: 101EG2 ** ON A/C NOT FOR ALL

1. Reason for the Job
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	CAP - PROTECTION
No specific	AR	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

B. Work Zones and Access Panels

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

C. Referenced Information

REFERENCE	DESIGNATION
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
Hydraulic Control Unit (HCU) Proximity Sensors
Hydraulic Control Unit (HCU) Proximity Sensors - Tab Washer Installation
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

3. Job Set-up
Subtask 78-31-22-941-050-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 78-31-22-864-050-A ** ON A/C NOT FOR ALL

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 overhead panel, on the HYD/FUEL panel 40VU.
(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 78-31-22-865-050-A ** ON A/C NOT FOR ALL

C. Open, safety and tag this(these) circuit breaker(s):

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

Subtask 78-31-22-040-050-A ** ON A/C NOT FOR ALL

D. Deactivation of the Thrust Reverser for Maintenance

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).

Subtask 78-31-22-010-050-A ** ON A/C NOT FOR ALL

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:
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENG 1)
413AT
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENG 2)
423AT

4. Procedure

CAUTION: WIPE CLEAN ALL PARTS AND TOOLS AS NECESSARY TO REMOVE UNWANTED DEBRIS AND PREVENT DAMAGE TO THE ENGINE.

Subtask 78-31-22-020-050-A ** ON A/C NOT FOR ALL

A. Removal of the Hydraulic Control Unit (HCU) Proximity Sensor
(1) Disconnect the CH A ICU proximity sensor harness from the proximity sensor (1) (100EG).
(2) Disconnect the CH B ICU proximity sensor harness from the proximity sensor (4) (101EG).
(3) Remove the proximity sensors (1) and (4).
(a) Bend the tab washers (2) with the A701191 HCU PROX. SENSOR INSTALL to unlock the two nuts (3).
(b) Carefully, remove the two nuts (3) and the two tab washers (2) from the proximity sensors (1) and (4) with the A708405 PROX SENSOR R/I TOOL.
(c) Remove the proximity sensors (1) and (4) from the HCU.
(4) Install the CAP - PROTECTION on the connectors of the harnesses and the proximity sensors (1) and (4).
(5) 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 the COVER - PROTECTION as necessary to prevent damage to the engine.

[Rev.10 from 2021] 2026.04.01 03:31:27 UTC