Removal of the Hydraulic Control Unit [CFMB]

TASK 78-31-51-000-042-A
Removal of the Hydraulic Control Unit

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	CAN - DRAIN
No specific	AR	CAP - PROTECTION
No specific	AR	COVER - PROTECTION
No specific	AR	PLIERS - NOSE, SOFT, LONG
No specific	AR	PLUG - BLANKING
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

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

C. Referenced Information

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

3. Job Set-up
Subtask 78-31-51-941-051-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 78-31-51-010-052-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the fan cowl doors (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 in the right side of engine.

Subtask 78-31-51-040-051-A ** ON A/C NOT FOR ALL

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

Subtask 78-31-51-010-053-A ** ON A/C NOT FOR ALL

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

Subtask 78-31-51-614-050-A ** ON A/C NOT FOR ALL

E. Depressurization of the Hydraulic Reservoirs
(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 78-31-51-020-051-B ** ON A/C NOT FOR ALL

A. Removal of 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 clamps (10, 12) to the interface bracket (15).
(5) Move the right thrust reverser harness (30) aside.
(6) Put a COVER - PROTECTION on the engine case to keep hydraulic fluid off.
(7) Disconnect hoses:

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.

(a) Disconnect the supply hose (50), the return hose (45), and the latch return hose (40) from the left side of the HCU (20). Drain hydraulic fluid into the CAN - DRAIN.
(b) Disconnect the latch supply hose (55), the head supply hose (60), and the rod supply hose (65) from the pipes at the interface bracket (15).
(8) Disconnect the CVR pipe (100) from the check valve restrictor.
(9) Remove the nut (95) that attaches the CVR pipe (100) to the support (90). Remove the CVR pipe (100).
(10) Remove the nut (105) that attaches the rod supply pipe (75) to the interface bracket (15).
(11) Remove the nuts (80) and (85) that attach the latch return pipe (35), the head supply pipe (70) and the support (90) to the interface bracket (15).
(12) Disconnect the latch supply pipe (110), the head supply pipe (70) and the rod supply pipe (75) from the right side of the HCU (20).
(13) Remove the bolts (115) that attach the HCU (20) to the forward frame. Remove the HCU (20).
(14) Remove the thermal blankets as follows:

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

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 bolts (120) that attach the interface bracket (15) to the HCU (20).
(b) Remove the thermal blankets (175) and (180) from the HCU (20).
(15) Remove the unions (130), (135) and (140) from the left side of the HCU (20). Discard the packings (125), (145) and (150).
(16) Remove the unions (140), (160) and (165) from the right side of the HCU (20). Discard the packings (145), (155) and (170).
(17) Install PLUG - BLANKING on all open lines and HCU ports.
(18) Install CAP - PROTECTION on the three electrical connectors.

[Rev.10 from 2021] 2026.04.01 03:25:31 UTC