Removal of the Direction Control Unit (DCU) [CFML]

TASK 78-31-52-000-802-A
Removal of the Direction Control Unit (DCU)

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.

FIN: 4001EG

1. Reason for the Job
A. This task gives the instructions to remove the Direction Control Unit (DCU) from the thrust reverser.
B. The upper actuator is also known as the synchronized locking feedback actuator.
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	1	PLIERS - JAWED, SOFT
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
437AL, 438AR, 451AL
FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
447AL, 448AR, 461AL

C. Referenced Information

REFERENCE	DESIGNATION
TASK 70-70-00-910-804-A	Electrical Standard Practices
TASK 71-13-00-010-803-A	Opening of the Fan Cowl Doors
TASK 71-51-43-000-806-A	Removal of the Thrust Reverser Actuation System Electrical Harnesses
TASK 78-30-00-040-807-A	Deactivation of the Thrust Reverser System for Nacelle Maintenance (ICU)
TASK 78-31-44-000-802-A	Removal of the Sync Tubes, Sync Shafts, Flex Tubes and Flex Shaft
TASK 78-31-49-680-801-A	Draining of the Thrust Reverser Hydraulic Tubes
TASK 78-36-00-010-806-A	Opening of the Thrust Reverser Cowl Doors
TASK 78-36-00-410-806-A	Closing of the Thrust Reverser Cowl Doors
Direction Control Unit (DCU)
FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 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, ENGINE 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 78-31-52-941-053-A

A. Safety Precautions
(1) On the center pedestal, on ENG panel 115VU:
(a) Make sure that the ENG/MODE selector switch is in the NORM position.
(b) Make sure that the ENG/MASTER 1(2) control switch was in the OFF position not less than five minutes before you do this procedure.
(c) Put a WARNING NOTICE(S) in position to tell persons not to operate:

The ENG/MODE selector switch
The ENG/MASTER 1(2) control switch.

(2) On the ENG section of maintenance panel 50VU:
(a) Make sure that the ON legend of the FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) in position to tell persons not to energize FADEC 1(2).

Subtask 78-31-52-010-056-A

B. Get Access
(1) Open the fan cowl doors (Ref. AMM TASK 71-13-00-010-803):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
437AL 438AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
447AL 448AR
(2) Put an ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position below the left fan cowl door.

Subtask 78-31-52-864-052-A

C. 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, ENGINE 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, ENGINE 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 78-31-52-440-052-A

D. Deactivation of the Thrust Reverser System for Nacelle 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 nacelle maintenance (Ref. AMM TASK 78-30-00-040-807).

Subtask 78-31-52-010-058-A

E. Get Access
(1) Open the left thrust-reverser cowl-door (Ref. AMM TASK 78-36-00-010-806):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
451AL
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
461AL

Subtask 78-31-52-680-050-A

F. Drain the thrust reverser hydraulic tubes attached to the actuator (Ref. AMM TASK 78-31-49-680-801).

4. Procedure

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.

WARNING: OBEY THE HYDRAULIC SAFETY PROCEDURES.

WARNING: DO NOT TOUCH THE HYDRAULIC SYSTEM COMPONENTS FOR A SHORT TIME AFTER THE ENGINE IS SHUTDOWN. THE ENGINE COMPONENTS STAY HOT FOR SOME TIME AND CAN CAUSE INJURY.

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.

Subtask 78-31-52-020-051-A

A. Removal of the Directional Control Unit (DCU)
(1) Disconnect the electrical connector (4) and the electrical connector (5) from the DCU (2) (Ref. AMM TASK 70-70-00-910-804).

NOTE: If necessary, use a PLIERS - JAWED, SOFT.

(2) Remove the tertiary lock system harnesses (1) from the removal path of the DCU (2) and upper actuator (9) as follows:
(a) Disconnect the tertiary lock system harnesses (1) from the five locations and move them to the opposite of the upper actuator (9) from the DCU (2) (Ref. AMM TASK 71-51-43-000-806).
(b) Disconnect the tertiary lock system harnesses (1) from the upper actuator (9) and move it aside (Ref. AMM TASK 71-51-43-000-806).
(3) Loosen the over-the-top flex tube (6) from the tee connector (3) on the upper actuator (9) (Ref. AMM TASK 78-31-44-000-802).
(4) Loosen the coupling nut of the pylon hose (20) from the hydraulic tube (12).
(5) Loosen the coupling nut of the pylon hose (21) from the hydraulic tube (11).
(6) Loosen the coupling nut to disconnect the hydraulic tube (11) from the DCU (2).
(7) Loosen the coupling nut to disconnect the hydraulic tube (12) from the upper actuator (9).
(8) Loosen the coupling nut to disconnect the hydraulic tube (11) from the upper actuator (9).
(9) Remove the hydraulic tube (11) as follows:
(a) Loosen the two nuts (17) that attach the hydraulic tube (11) to the bracket (7).
(b) Remove the pylon hose (21), one nut (17) and one washer (19) from the hydraulic tube (11).
(c) Remove the hydraulic tube (11), one nut (17) and one washer (19).
(10) Loosen the coupling nuts of the hydraulic tube (10) from the DCU (2) and tee connector (3) and remove the hydraulic tube (10).
(11) Remove the hydraulic tube (12) as follows:
(a) Loosen the two nuts (17) that attach the hydraulic tube (12) to the bracket (7).
(b) Remove the pylon hose (20), one nut (17) and one washer (19) from the hydraulic tube (12).
(c) Loosen the coupling nut to disconnect the hydraulic tube (12) from the DCU (2).
(d) Remove the hydraulic tube (12), one nut (17) and one washer (19).
(12) Remove the four bolts (14) and two washers (16) that attach the DCU (2) and bracket (15) to the forward frame (8) and remove the DCU (2) from the nacelle.
(13) Install COVER - PROTECTION and CAP - PROTECTION on all the openings, tubes, hoses and connectors.
(14) Close the left thrust-reverser cowl-door (Ref. AMM TASK 78-36-00-410-806):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
451AL
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
461AL

[Rev.10 from 2021] 2026.04.01 03:35:32 UTC