Removal of the Thrust Reverser Actuation System (TRAS) Hydraulic Control Unit (HCU) [PW11]

TASK 78-31-01-000-801-A
Removal of the Thrust Reverser Actuation System (TRAS) Hydraulic Control Unit (HCU)

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.

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.

WARNING: YOU MUST NOT GET HYDRAULIC FLUID ON YOUR SKIN, IN YOUR EYES OR IN YOUR MOUTH. THE HYDRAULIC FLUID IS POISONOUS AND CAN BE ABSORBED INTO YOUR BODY. IF YOU ACCIDENTALLY GET HYDRAULIC FLUID IN YOUR EYES, MOUTH OR ON YOUR SKIN, FLUSH WITH WATER AND GET MEDICAL AID.

WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

CAUTION: YOU MUST NOT LET HYDRAULIC FLUID FALL ON THE ENGINE. UNWANTED HYDRAULIC FLUID MUST BE REMOVED IMMEDIATELY WITH A CLEAN LINT- FREE CLOTH. THE HYDRAULIC FLUID CAN CAUSE DAMAGE TO THE SURFACE PROTECTION AND SOME PARTS.

ZONE: 400
FIN: 4310EG1 ** ON A/C NOT FOR ALL
FIN: 4310EG2 ** 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)
No specific	AR	CAP - PROTECTION
No specific	1	CONTAINER 5 L (1.32 USGAL)
No specific	AR	COVER - PROTECTION
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	WARNING NOTICE(S)

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.PU1-0001)	cloth

C. 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

D. Referenced Information

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
Thrust Reverser Actuation System (TRAS) Hydraulic Control Unit (HCU)
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 78-31-01-941-050-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 78-31-01-864-050-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 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 78-31-01-865-050-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	DCV B/ENG1 PWR SUPPLY	103KS1	K44
121VU	DCV A/ENG1 PWR SUPPLY	102KS1	K42
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	DCV A/ENG1 PWR SUPPLY	102KS1	N44
121VU	DCV B/ENG1 PWR SUPPLY	103KS1	Q44
121VU	ICU A/ENG1 PWR SUPPLY	22KS1	R38
** ON A/C NOT FOR ALL
FOR FIN: 4020KM2 (POWER PLANTDEMOUNTABLE, ENG 2)
121VU	DCV B/ENG2 PWR SUPPLY	103KS2	K45
121VU	DCV A/ENG2 PWR SUPPLY	102KS2	K43
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	DCV A/ENG2 PWR SUPPLY	102KS2	N45
121VU	DCV B/ENG2 PWR SUPPLY	103KS2	Q45
121VU	ICU A/ENG2 PWR SUPPLY	22KS2	R39

Subtask 78-31-01-010-050-A ** ON A/C NOT FOR ALL

D. Get Access
(1) Put an ACCESS PLATFORM 2M (6 FT) 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

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

Subtask 78-31-01-020-050-A ** ON A/C NOT FOR ALL

A. Removal of the Hydraulic Control Unit (HCU)
(1) Disconnect the electrical harnesses:
(a) Disconnect the channel B Isolation Control Unit (ICU) proximity sensor harness from the TRAS HCU (1).
(b) Disconnect the channel A ICU proximity sensor harness from the TRAS HCU (1).
(2) Disconnect the hydraulic connections:

CAUTION: HYDRAULIC FLUID CAN CAUSE DAMAGE TO EQUIPMENT. IF HYDRAULIC FLUID FALLS ON A SURFACE, IMMEDIATELY CLEAN THE SURFACE WITH A CLEAN CLOTH.

(a) Put the cloth (Material No.PU1-0001) below the aft return line to collect hydraulic fluid that possibly can spill.
1 Disconnect the aft return line from the aft end of the HCU (1).
2 Drain the hydraulic fluid from the return line into the CONTAINER 5 L (1.32 USGAL).
(b) Put the cloth (Material No.PU1-0001) below the supply line to collect hydraulic fluid that possibly can spill.
1 Disconnect the supply line from the aft end of the HCU (1).
2 Drain the hydraulic fluid from the supply line into the CONTAINER 5 L (1.32 USGAL).

WARNING: USE PROTECTIVE GOGGLES WHEN YOU REMOVE OR INSTALL A COTTER PIN. EACH TIME YOU REMOVE A COTTER PIN DURING THE TASK, DISCARD IT IMMEDIATELY. A LOOSE COTTER PIN CAN CUT YOU OR MAKE YOU BLIND.

(c)
1 Remove the cotter pin (2) and the nut (3) that attach the upper inhibit cable to the HCU (1).
2 Discard the cotter pin (2).
(d) Disconnect the upper inhibit cable from the HCU (1).
(e) Disconnect the Direction Control Unit (DCU) coil harness from the HCU (1).
(f) Put the cloth (Material No.PU1-0001) below the right return line to collect hydraulic fluid that possibly can spill.
(g) Disconnect the right return line from the right side of the HCU (1).
(h) Drain the hydraulic fluid from the return line into the CONTAINER 5 L (1.32 USGAL).
(i) Disconnect the deploy line from the right side of the HCU (1).
(j) Drain the hydraulic fluid from the deploy line into the CONTAINER 5 L (1.32 USGAL).
(k) Put the cloth (Material No.PU1-0001) below the stow line to collect hydraulic fluid that possibly can spill.
(l) Disconnect the stow line from the right side of the HCU (1).
(m) Drain the hydraulic fluid from the stow line into the CONTAINER 5 L (1.32 USGAL).
(n) Disconnect the ICU coil harness from the HCU (1).
(o) Disconnect the channel A DCU proximity sensor harness from the HCU (1).
(p) Disconnect the channel B DCU proximity sensor harness from the HCU (1).
(3) Remove the HCU (1).
(a) Remove the four bolts (4) and the four washers (5) that attach the HCU (1) to the bracket on the pylon.
(b) Remove the varnish from the bolt as necessary.
(c) Remove the HCU (1).
(d) Drain the remaining hydraulic fluid in the HCU (1) into the CONTAINER 5 L (1.32 USGAL).
(4) 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 and the CAP - PROTECTION as necessary to prevent damage to the engine.

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