Removal of the Pressure-Off Brake of the Slat Power Control Unit

TASK 27-84-52-000-001-A
Removal of the Pressure-Off Brake of the Slat Power Control Unit

WARNING: MAKE SURE THAT THE GROUND SAFETY-LOCKS ARE IN POSITION ON THE LANDING GEAR. THIS WILL PREVENT UNWANTED MOVEMENT OF THE LANDING GEAR, AND THUS POSSIBLE INJURY TO PERSONS AND DAMAGE TO THE AIRCRAFT AND/OR EQUIPMENT.

WARNING: MAKE SURE THAT THE TRAVEL RANGES OF THE FLIGHT CONTROLS SURFACES ARE CLEAR. MOVEMENT OF FLIGHT CONTROLS CAN CAUSE INJURY TO PERSONS AND/OR DAMAGE TO EQUIPMENT.

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.

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 3M (10 FT)- ADJUSTABLE
No specific	AR	CONTAINER 5 L (1.32 USGAL)
No specific	AR	PLUG - BLANKING
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	AR	WARNING NOTICE(S)
98D27504030001	1	LOCK-TORQUE SHAFT (FLAPS AND SLATS) WITH CLAMP-PIVOT
98D27803000000	1	LOCKING TOOL-FLAP SLAT LEVER,INT. POSITION

B. Referenced Information

REFERENCE	DESIGNATION
TASK 27-00-00-480-002-A	Installation of the Flap/Slat Control-Lever Locking Tool (98D27803000000)
TASK 27-80-00-866-005-A	Retracting the Slats on the Ground
TASK 29-00-00-864-001-A	Put the Related Hydraulic System in the Depressurized Configuration before Maintenance Action
TASK 29-14-00-614-001-A	Depressurization of the Hydraulic Reservoirs
TASK 32-12-00-010-001-A	Open the Main Gear Doors for Access
Pressure-Off Brake

3. Job Set-up
Subtask 27-84-52-866-050-A

A. Retraction of the Slats
(1) Retract the slats to the 0 degree position (Ref. AMM TASK 27-80-00-866-005).
(2) Install the 98D27803000000 LOCKING TOOL-FLAP SLAT LEVER,INT. POSITION (Ref. AMM TASK 27-00-00-480-002) on the slat/flap control lever.

Subtask 27-84-52-865-050-A

B. Open, safety and tag this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	FLIGHT CONTROLS/SLT/CTL AND MONG/SYS1	5CV	B06
** ON A/C NOT FOR ALL
49VU	FLIGHT CONTROLS/SLT/CTL AND MONG/SYS1	5CV	B01
** ON A/C ALL
121VU	FLIGHT CONTROLS/SLT/CTL/SYS2	7CV	R21

Subtask 27-84-52-010-050-A

C. Open the main doors of the main gear (Ref. AMM TASK 32-12-00-010-001).

Subtask 27-84-52-860-050-A

D. Aircraft Maintenance Configuration
(1) Put the ACCESS PLATFORM 3M (10 FT)- ADJUSTABLE in position at the opening of the main door of the main gear.
(2) Make sure that the Green and Blue hydraulic systems are depressurized and put them in the maintenance configuration (Ref. AMM TASK 29-00-00-864-001).
(3) Depressurize the reservoirs of the Blue and the Green hydraulic systems (Ref. AMM TASK 29-14-00-614-001).
(4) Put the WARNING NOTICE(S) in position to tell persons not to pressurize the hydraulic systems.
(5) Install the 98D27504030001 LOCK-TORQUE SHAFT (FLAPS AND SLATS) WITH CLAMP-PIVOT to lock the left slat transmission.
(6) Install the 98D27504030001 LOCK-TORQUE SHAFT (FLAPS AND SLATS) WITH CLAMP-PIVOT to lock the right slat transmission.
(7) Put a CONTAINER 5 L (1.32 USGAL) in position below the Power Control Unit (PCU) (1).

4. Procedure
Subtask 27-84-52-020-050-A

CAUTION: USE A SECOND WRENCH TO APPLY COUNTERTORQUE TO THE UNION WHEN YOU DISCONNECT/CONNECT HYDRAULIC LINES ON UNIONS. IF YOU DO NOT USE THE SECOND WRENCH, THERE IS A RISK THAT YOU WILL LOOSEN OR TIGHTEN THE UNION TOO MUCH.

CAUTION: DO NOT USE POINTED, SHARP OR METAL TOOLS TO REMOVE AND INSTALL PACKINGS OR RETAINERS. ALSO MAKE SURE THAT YOU USE THE CORRECT TOOLS TO REMOVE AND INSTALL LOCKING WASHERS OR RETAINING RINGS. IF YOU DO NOT USE THE CORRECT TOOLS, YOU CAN EASILY CAUSE DAMAGE TO THESE COMPONENTS.

CAUTION: YOU MUST BE CAREFUL WHEN YOU MOVE THE TRANSFER TUBES AND THE ADJACENT COMPONENTS. IF YOU ARE NOT CAREFUL, YOU CAN EASILY CAUSE DAMAGE TO THEM.

A. Removal of the Pressure-Off Brake

Pressure-Off Brake

NOTE: The removal procedure for the pressure-off brake at the valve block 25CV is given. The removal procedure for the pressure-off brake at the valve block 26CV is almost the same. The differences in the procedures are given.

(1) Remove the pressure-off brake (POB) (41) together with the hydraulic motor (7) and the block assembly (23) from the differential gearbox (40).
(a) Disconnect and remove the hydraulic lines (11) from the valve block assembly (23).
(b) Remove and discard the tie wrap (9) and disconnect the seal drain line (10).
(c) Disconnect and remove the case drain line (8) from the hydraulic motor (7).
(d) Install the blanking caps on the open line ends (8),(10),(11).
(e) Install the PLUG - BLANKING in the ports of the PCU (1).
(f) Disconnect the electrical connector (22) from the valve block assembly (23).
(g) Put blanking caps on the disconnected electrical connectors and receptacles.
(h) Support the POB (41), the hydraulic motor (7) and the valve block assembly (23).
(i) Remove the bolts (3) and the washers (2).
(j) Remove the nuts (24) and the washers (25) from the studs (42).
(k) Remove the POB (41) together with the hydraulic motor (7) and the valve block assembly (23).
(2) Remove the POB (41) from the hydraulic motor (7) and the valve block assembly (23).
(a) Remove the bolts (6) and the washers (5).
(b) Carefully remove the hydraulic motor (7) and the POB (41) from the transfer tubes (14),(33) on the valve block assembly (23).
(c) Remove and discard the packing (4).
(3) Remove and discard the locking washers (21) and the retaining ring (30) from the transfer tubes (14) and (33).
(4) Remove the transfer tubes (14) and (33) from the valve block assembly (23).
(5) Carefully remove and discard all the packings (13),(32) and all the retainers (12),(31) from the transfer tubes (14) and (33).

[Rev.10 from 2021] 2026.03.31 23:57:41 UTC