Removal of the Hydraulic Control Unit [CFMI]

TASK 78-31-51-000-040-A
Removal of the Hydraulic Control Unit

WARNING: PUT THE SAFETY DEVICES AND THE WARNING NOTICES IN POSITION BEFORE YOU START A TASK ON OR NEAR:

THE FLIGHT CONTROLS
THE FLIGHT CONTROL SURFACES
THE LANDING GEAR AND THE RELATED DOORS
COMPONENTS THAT MOVE.

MOVEMENT OF COMPONENTS CAN KILL OR CAUSE INJURY TO PERSONS AND/OR CAN CAUSE DAMAGE TO THE EQUIPMENT.

WARNING: WEAR A FACE SHIELD WHICH IS RESISTANT TO HIGH PRESSURE JETS WHEN YOU WORK ON PRESSURIZED SYSTEMS.

WARNING: DO NOT GET THE FLUID ON YOUR SKIN OR IN YOUR EYES. IF YOU DO:

FLUSH IT AWAY WITH CLEAN WATER
GET MEDICAL AID.

CAUTION: USE TWO WRENCHES TO REMOVE OR INSTALL THE TUBE COUPLING NUTS:

ONE WRENCH TO HOLD THE UNION, AND
ONE TO LOOSEN OR TIGHTEN THE COUPLING NUT.

THIS PREVENTS DAMAGE TO THE PARTS.

CAUTION: MAKE SURE THERE IS NO UNWANTED MATERIAL IN THE PORTS AND ORIFICES OR DAMAGE CAN OCCUR.

CAUTION: YOU MUST INSTALL HYDRAULIC TUBES WITH HYDRAULIC FLUID AS LUBRICANT.

FIN: 4101KS1 ** ON A/C NOT FOR ALL
FIN: 4101KS2 ** 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	AR	ACCESS PLATFORM 1M(3 FT)
No specific	AR	CAP - BLANKING
No specific	AR	CAP - PROTECTION
No specific	AR	PLIERS - NOSE, SOFT, LONG
No specific	AR	WARNING NOTICE(S)

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.14SBA1)	Textile-Lint free Cotton -

C. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
FOR [1000EM1] (ENGINE-1)
437AL, 438AR, 452AR
FOR [1000EM2] (ENGINE-2)
447AL, 448AR, 462AR

D. Referenced Information

REFERENCE	DESIGNATION
TASK 29-14-00-614-001-A	Depressurization of the Hydraulic Reservoirs
TASK 71-13-00-010-040-A	Opening of the Fan Cowl Doors
TASK 78-30-00-481-041-A	Make the Thrust Reverser Unserviceable for Maintenance
TASK 78-36-00-010-040-A	Opening of the Thrust Reverser Doors
Hydraulic Control Unit
Hydraulic Control Unit Thermal Blankets

3. Job Set-up
Subtask 78-31-51-941-060-A ** ON A/C NOT FOR ALL

A. 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 78-31-51-010-064-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the fan cowls (Ref. AMM TASK 71-13-00-010-040):
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR
(2) Put the ACCESS PLATFORM 1M(3 FT) in position.

Subtask 78-31-51-040-059-A ** ON A/C NOT FOR ALL

C. Make the thrust reverser unserviceable (Ref. AMM TASK 78-30-00-481-041).

Subtask 78-31-51-010-065-A ** ON A/C NOT FOR ALL

D. Open the right thrust reverser door (Ref. AMM TASK 78-36-00-010-040):
(1) FOR [1000EM1] (ENGINE-1)
452AR
(2) FOR [1000EM2] (ENGINE-2)
462AR

Subtask 78-31-51-614-052-A ** ON A/C NOT FOR ALL

E. Depressurize the aircraft hydraulic systems
(1) For engine 1 depressurize the Green hydraulic reservoir (Ref. AMM TASK 29-14-00-614-001).
(2) For engine 2 depressurize the Yellow hydraulic reservoir (Ref. AMM TASK 29-14-00-614-001).

4. Procedure
Subtask 78-31-51-020-054-A ** ON A/C NOT FOR ALL

A. Remove the Parts that Follow from the Hydraulic Control Unit (HCU)
(1) Disconnect the electrical connector 4101KS-A from solenoid A of the HCU.

NOTE: If necessary, use the PLIERS - NOSE, SOFT, LONG to loosen the electrical connectors.

(2) Disconnect the electrical connector 4101KS-B from solenoid B of the HCU.
(3) Disconnect the electrical connector 4102KS-A from the HCU pressure switch.
(4) Remove the nut (25) and the bolt (5) that attach the clamp (10) to the interface bracket (15).
(5) Move the right thrust reverser harness (30) aside.
(6) Put a Textile-Lint free Cotton - (Material No.14SBA1) on the engine below the HCU to protect it from the hydraulic fluid.

Subtask 78-31-51-020-055-A ** ON A/C NOT FOR ALL

B. Remove the Parts that Follow from Left Side of the HCU

WARNING: DO NOT GET THE FLUID ON YOUR SKIN OR IN YOUR EYES. IF YOU DO:

FLUSH IT AWAY WITH CLEAN WATER
GET MEDICAL AID.

(1) Drain the hydraulic fluid into the drain can.
(2) Disconnect the latch return hose (40) from the HCU (20).
(3) Disconnect the return hose (50) from the HCU (20).
(4) Disconnect the supply hose (45) from the HCU (20).
(5) Disconnect the latch supply hose (55) from the pipes at the interface bracket (15).
(6) Disconnect the head supply hose (60) from the pipes at the interface bracket (15).
(7) Disconnect the rod supply hose (65) from the pipes at the interface bracket (15).

Subtask 78-31-51-020-056-A ** ON A/C NOT FOR ALL

C. Remove the Parts that Follow from Right Side of the HCU
(1) Drain the hydraulic fluid into the drain can.
(2) Remove the nut (85) that attaches the latch return pipe (35) to the interface bracket (15).
(3) Remove the nut (80) that attaches the head supply pipe (110) to the interface bracket (15).
(4) Remove the nut (105) that attaches the rod supply pipe (75) to the interface bracket (15).
(5) Disconnect the head supply pipe (110) from the HCU (20).
(6) Disconnect the rod supply pipe (75) from the HCU (20).
(7) Disconnect the latch supply pipe (70) from the HCU (20).

Subtask 78-31-51-020-058-B ** ON A/C NOT FOR ALL

D. Remove the HCU from the Engine
(1) Remove the bolts (115) that attach the HCU (20) to the forward frame and remove the HCU (20).
(2) Remove the parts that follow from the HCU.

NOTE: Removal of the thermal blanket is not required, and is included for reference only. The thermal blanket must be installed if the HCU is to be returned to the supplier.

(a) Remove the thermal blankets as follows:

Hydraulic Control Unit Thermal Blankets ** ON A/C NOT FOR ALL

1 Remove the bolt (120) that attach the interface bracket (15) to the HCU (20).
2 Remove the thermal blankets (175) and (180) from the HCU (20).
(b) Remove the unions (130), (135) and (140) from the left side of the HCU (20). Discard the packings (125), (145) and (150).
(c) Remove the unions (140), (160) and (165) from the right side of the HCU (20). Discard the packings (145), (155) and (170).
(d) Install CAP - PROTECTION on the tubes, hoses, HCU fittings and all opened HCU ports.
(e) Put the CAP-BLANKING on each disconnected electrical connector and receptacle.

[Rev.10 from 2021] 2026.04.02 07:42:01 UTC