Bleeding Procedure of the Yellow Hydraulic System Upstream of the Engine Pump

TASK 29-00-00-870-004-A
Bleeding Procedure of the Yellow Hydraulic System Upstream of the Engine Pump

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: 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.

1. Reason for the Job
Do this procedure after maintenance of the Yellow hydraulic system upstream of the engine pump.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	CONTAINER 10 L(2 1/2 USGAL)
No specific	AR	SAFETY CLIP - CIRCUIT BREAKER
No specific	Torque wrench: range to between 289 and 262 lbf.in (3.27 and 2.96 m.daN )

B. Referenced Information

REFERENCE	DESIGNATION
TASK 12-12-29-611-001-A	Fill the Hydraulic Fluid Reservoir with a Hand Pump
TASK 12-12-29-611-002-A	Fill the Hydraulic Fluid Reservoir with a Hydraulic Service Cart
TASK 29-00-00-210-001-A	Check for Air in the Green/Blue/Yellow Hydraulic System
TASK 29-00-00-910-002-A	Safety Procedures of the Hydraulic System
TASK 29-14-00-614-002-A	Pressurization of the Hydraulic Reservoirs through the Ground Connector
TASK 29-14-00-614-002-A-01	Pressurization of the Hydraulic Reservoirs with the Auxiliary Power Unit (APU)
TASK 71-13-00-010-010-A	Opening of the Fan Cowls 437AL(447AL),438AR(448AR)
TASK 71-13-00-010-040-A	Opening of the Fan Cowl Doors
TASK 71-13-00-010-040-B	Opening of the Fan Cowl Doors
TASK 71-13-00-410-010-A	Closing of the Fan Cowls 437AL(447AL),438AR(448AR)
TASK 71-13-00-410-040-A	Closing of the Fan Cowl Doors
TASK 71-13-00-410-040-B	Closing of the Fan Cowl Doors
TASK 29-00-00-870-005-A	Bleeding Procedure of the Yellow Hydraulic System Upstream of the PTU (for corrective action)
TASK 29-00-00-870-006-A	Bleeding Procedure of the Yellow Hydraulic System Upstream of the Yellow E-Pump (for corrective action)
TASK 29-00-00-870-007-A	Bleeding Procedure of the Yellow Hydraulic System Downstream of the Engine Pump (for corrective action)
TASK 29-13-00-00	YELLOW MAIN HYDRAULIC POWER - DESCRIPTION AND OPERATION

3. Job Set-up
Subtask 29-00-00-860-064-A

A. Aircraft Maintenance Configuration

WARNING: OBEY THE HYDRAULIC SAFETY PROCEDURES.

(1) Obey the hydraulic safety procedures (Ref. AMM TASK 29-00-00-910-002).
(2) Make sure that the replaced component is correctly installed.
(3) Make sure that the hydraulic reservoir of the Yellow hydraulic system is pressurized. If necessary pressurize it (Ref. AMM TASK 29-14-00-614-002).

Subtask 29-00-00-865-070-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	HYDRAULIC/G HYD/PUMP ENG1/CTL	1701GK	H12
** ON A/C NOT FOR ALL
121VU	HYDRAULIC/G HYD/PUMP ENG1/CTL	1701GK	R35
** ON A/C ALL
121VU	HYDRAULIC/Y HYD/PUMP ENG2/CTL	3701GD	Q36

Subtask 29-00-00-010-063-A

C. Open the left fan cowl door (Ref. AMM TASK 71-13-00-010-040) or
(Ref. AMM TASK 71-13-00-010-040) or
(Ref. AMM TASK 71-13-00-010-010) or
(Ref. AMM D/O 71-13-00-01).

4. Procedure
Subtask 29-00-00-870-059-A

A. Bleeding Procedure of the Yellow Hydraulic System Upstream of the Engine Pump

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.

(1) Identify the locations of the related components to do the bleeding procedure (Ref. AMM D/O 29-13-00-00).
(2) Put a CONTAINER 10 L(2 1/2 USGAL) under the engine pump.
(3) Loosen the nut of the case drain hose until the air (or the hydraulic fluid mixed with air bubbles) comes out of the connection.
(4) Tighten the nut of the case drain hose when the hydraulic fluid flows freely.
(5) TORQUE the nut to between 289 and 262 lbf.in (3.27 and 2.96 m.daN )

.
(6) Do the check for Air in the Yellow hydraulic system (Ref. AMM TASK 29-00-00-210-001).
(a) If the check for air is not in the given limits, do the bleeding procedure again.

NOTE: Do not do the bleeding procedure more than two times.

(b) If the result is not satisfactory after two bleeding cycles, you must:

do the bleeding procedure of the Yellow hydraulic system upstream of the PTU (Ref. AMM TASK 29-00-00-870-005).
do the bleeding procedure of the Yellow hydraulic system upstream of the Yellow E-Pump (Ref. AMM TASK 29-00-00-870-006).
do the bleeding procedure of the Yellow hydraulic system downstream of the engine pump (Ref. AMM TASK 29-00-00-870-007).

(7) Remove the container.
(8) Make sure that the level of the hydraulic fluid in the reservoir of the Yellow hydraulic system is correct. Add fluid as necessary (Ref. AMM TASK 12-12-29-611-001) or (Ref. AMM TASK 12-12-29-611-002).
(9) Make sure that the air pressure in the reservoir of the Yellow hydraulic system is not less than 50 psi (3.4474 bar). If necessary pressurize the reservoir (Ref. AMM TASK 29-14-00-614-002).

5. Close-up
Subtask 29-00-00-410-065-A

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close the left fan cowl door (Ref. AMM TASK 71-13-00-410-040) or
(Ref. AMM TASK 71-13-00-410-040) or
(Ref. AMM TASK 71-13-00-410-010) or
(Ref. AMM D/O 71-13-00-41).

Subtask 29-00-00-865-071-A

B. Remove the safety clip(s) and the tag(s) and close this(these) circuit breaker(s):

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
49VU	HYDRAULIC/G HYD/PUMP ENG1/CTL	1701GK	H12
** ON A/C NOT FOR ALL
121VU	HYDRAULIC/G HYD/PUMP ENG1/CTL	1701GK	R35
** ON A/C ALL
121VU	HYDRAULIC/Y HYD/PUMP ENG2/CTL	3701GD	Q36

[Rev.10 from 2021] 2026.04.01 00:13:14 UTC