Removal of the Thrust Reverser Hydraulic Control Unit (HCU) [IAE]

TASK 78-31-51-000-010-A
Removal of the Thrust Reverser Hydraulic Control Unit (HCU)

WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE PARTS AFTER THE ENGINE SHUTDOWN. USE APPLICABLE THERMAL GLOVES. THE ENGINE PARTS CAN STAY HOT FOR ONE HOUR AFTER SHUTDOWN AND CAN BURN YOU.

WARNING: DO NOT GET HYDRAULIC FLUID ON YOUR SKIN, IN YOUR EYES OR IN YOUR MOUTH. HYDRAULIC FLUID IS POISONOUS AND CAN GO THROUGH YOUR SKIN AND INTO YOUR BODY. FLUSH HYDRAULIC FLUID FROM YOUR EYES, MOUTH OR SKIN WITH WATER. GET MEDICAL AID IF YOU GET HYDRAULIC FLUID IN YOUR EYES OR MOUTH.

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

ZONE: 400
FIN: 4101KS1 ** ON A/C NOT FOR ALL
FIN: 4101KS2 ** ON A/C NOT FOR ALL

1. Reason for the Job
This task supplies the data to remove the thrust reverser Hydraulic Control Unit (HCU).
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE
No specific	AR	CAP - BLANKING
No specific	1	CONTAINER 10 L(2 1/2 USGAL)
No specific	1	PLUG - BLANKING
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
400	POWER PLANT, NACELLES AND PYLONS
FOR [1000EM1] (ENGINE-1)
437AL, 438AR
FOR [1000EM2] (ENGINE-2)
447AL, 448AR

C. Referenced Information

REFERENCE	DESIGNATION
TASK 29-10-00-864-001-A	Depressurize the Green Hydraulic System
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 71-13-00-010-010-A	Opening of the Fan Cowls 437AL(447AL),438AR(448AR)
TASK 78-30-00-040-012-A	Deactivation of the Thrust Reverser Hydraulic Control Unit (HCU) for Ground Maintenance
Thrust-Reverser Hydraulic Control Unit

3. Job Set-up
Subtask 78-31-51-864-052-A ** ON A/C NOT FOR ALL

A. Depressurization of hydraulic systems:
(1) Put a WARNING NOTICE(S) in position to tell persons not to pressurize the applicable system.
(a) On the HYD/FUEL panel 40VU.
(b) On the ground service panel of the applicable hydraulic system.
(2) Depressurize the applicable hydraulic system (Ref. AMM TASK 29-10-00-864-001) or (Ref. AMM TASK 29-10-00-864-002).
(3) Depressurize the reservoir of the applicable hydraulic system (Ref. AMM TASK 29-14-00-614-001).

Subtask 78-31-51-941-055-A ** ON A/C NOT FOR ALL

B. Safety Precautions
(1) On the center pedestal, on the ENG panel 115VU:
(a) Put a WARNING NOTICE(S) to tell persons not to start the engine.
(2) Make sure that the engine 1(2) shutdown occurred not less than 5 minutes before you do this procedure.
(3) On the overhead maintenance panel 50VU:
(a) Make sure that the ON legend of the ENG/FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) to tell persons not to energize the FADEC 1(2).

Subtask 78-31-51-010-059-A ** ON A/C NOT FOR ALL

C. Get Access
(1) Open the fan cowls (Ref. AMM TASK 71-13-00-010-010):
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR
(2) Put the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in to position.

Subtask 78-31-51-040-055-A ** ON A/C NOT FOR ALL

D. Deactivate the thrust reverser

WARNING: MAKE SURE THAT THE THRUST REVERSER HYDRAULIC CONTROL UNIT (HCU) IS DEACTIVATED BEFORE YOU DO WORK ON OR AROUND THE THRUST REVERSER. IF THE HCU IS NOT DEACTIVATED, THERE IS A RISK OF UNWANTED THRUST REVERSER OPERATION WHICH CAN CAUSE INJURY TO PERSONS AND/OR DAMAGE TO EQUIPMENT.

(1) Deactivate the thrust reverser Hydraulic Control Unit (Ref. AMM TASK 78-30-00-040-012)

4. Procedure
Subtask 78-31-51-020-053-A ** ON A/C NOT FOR ALL

A. Removal of the HCU

Thrust-Reverser Hydraulic Control Unit ** ON A/C NOT FOR ALL

(1) Disconnect the electrical and hydraulic connections:
(a) Disconnect the two electrical connectors (8) from the HCU (3).
(b) Put the clean CONTAINER 10 L(2 1/2 USGAL) in position to catch the hydraulic fluid from the connections when they are opened.
(c) Disconnection of the hydraulic connections:

CAUTION: HOLD THE HYDRAULIC CONTROL UNIT CONNECTOR WITH A WRENCH WHILE YOU LOOSEN THE HYDRAULIC CONNECTIONS TO PREVENT DAMAGE TO THE HCU.

1 Disconnect the pressure hydraulic tube (2) and the return hydraulic tube (1) from the forward end of the HCU.
(d) Disconnect the pressure hydraulic tube (6) and the return hydraulic tube (7) from the aft end of the HCU.
(e) Remove the container and discard the drained hydraulic fluid.
(2) Remove the HCU (3):
(a) Remove the three bolts (5) and the three washers (4) that attach the HCU (3) to the pylon.
(b) Remove the HCU (3) from the pylon.
(3) Remove the return fitting (9) and packing (10) from the HCU (3).
(4) Discard the packing (10).
(5) Install the PLUG - BLANKING into the casing of the HCU (3).
(6) Install the CAP - BLANKING to all the openings.

[Rev.10 from 2021] 2026.04.01 03:27:38 UTC