Loss of the Brake-Accumulator Pressure

TASK 32-43-00-810-835-A
Loss of the Brake-Accumulator Pressure

1. Possible Causes

CTL VALVE-PARK BRK, ELEC [102GG]
SEL VALVE-ALTN BRK [99GG]
BRAKE RELIEF VALVE [3067GM]
ACCU-BRK YELLOW PRESS [2582GM]
CHECK VALVE Y [3058GM]
HYDR. PRESSURE TRANSMITTER [3068GN]
MANIFOLD [3016GM]
ABCU [95GG]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 12-14-32-614-002	Nitrogen Filling of the Yellow Hydraulic System, Brake Pressure Accumulator
AMM 29-14-00-614-001	Depressurization of the Hydraulic Reservoirs
AMM 29-14-00-614-002	Pressurization of the Hydraulic Reservoirs through the Ground Connector
AMM 29-32-11-000-004	Removal of the Hydraulic Pressure Transducer
AMM 29-32-11-400-004	Installation of the Hydraulic Pressure Transducer
AMM 32-43-34-000-001	Removal of the Alternate Braking Control Unit (ABCU)
AMM 32-43-34-400-001	Installation of the Alternate Braking Control Unit (ABCU)
AMM 32-43-51-000-001	Removal of the Alternate Braking Selector Valve
AMM 32-43-51-400-001	Installation of the Alternate Braking Selector Valve
AMM 32-44-00-720-002	Functional Check of Brake Accumulator System
AMM 32-44-11-000-001	Removal of the Accumulator
AMM 32-44-11-200-001	Functional Check of Parking/Emergency Brake Accumulator by Reading the Charge Pressure on the Accumulator Gauge
AMM 32-44-11-400-001	Installation of the Accumulator
AMM 32-44-15-000-001	Removal of the Pressure Relief Valve
AMM 32-44-15-400-001	Installation of the Pressure Relief Valve
AMM 32-44-17-000-001	Removal of the Brake Manifold
AMM 32-44-17-400-001	Installation of the Brake Manifold
AMM 32-45-51-000-001	Removal of the Parking-Brake Electrical Control-Valve
AMM 32-45-51-400-001	Installation of the Parking-Brake Electrical Control-Valve
Brake System with Parking Brake set to Off

3. Fault Confirmation
Subtask 32-43-00-720-050-A ** ON A/C NOT FOR ALL

A. Test
(1) Do the functional test of the brake accumulator system AMM 32-44-00-720-002.

4. Fault Isolation
Subtask 32-43-00-810-086-A ** ON A/C NOT FOR ALL

A. If the test confirms the fault:
(1) Do a check for leakage of the parking-brake control valve (102GG):
(a) On the Yellow brake-system relief-valve (3067GM) operate the manual depressurization pushbutton to release the accumulator pressure.
(b) On the Yellow hydraulic system, depressurize the hydraulic reservoir AMM 29-14-00-614-001.
(c) On the accumulator pressure gage (2585GM) make sure that nitrogen pressure is correct AMM 32-44-11-200-001.
(d) On the T-fitting, connected to the port D of the brake manifold (3016GM):
1 Disconnect the hydraulic return line that comes from the port B of the parking-brake control valve (102GG).
2 Install a plug on the open T-fitting connection.
(e) On the Yellow hydraulic system, pressurize the hydraulic reservoir AMM 29-14-00-614-002.
(f) Use the Yellow electric pump to pressurize the Yellow-pressure brake accumulator (2582GM) to 206 bar (2988 psi) and stop the pump.
(g) Do a check for hydraulic leakage of the parking-brake control valve (102GG).
1 If the leakage is more than 1 cm3/min:

Replace the CTL VALVE-PARK BRK, ELEC [102GG] AMM 32-45-51-000-001 AMM 32-45-51-400-001.

2 If leakage is in the permitted tolerances:

Operate the manual depressurization pushbutton of the relief valve (3067GM) to release the accumulator pressure.
Remove the plug on the T-fitting.
Connect the hydraulic return line, that comes from the port B of the parking-brake control valve (102GG), to the T-fitting.

(2) On the Yellow hydraulic system, pressurize the hydraulic reservoir AMM 29-14-00-614-002.

Use the Yellow electric pump to pressurize the Yellow-pressure brake accumulator (2582GM) to 206 bar (2988 psi) and stop the pump.

(3) If the fault continues:

Operate the manual depressurization pushbutton of the relief valve (3067GM) to release the accumulator pressure.
On the Yellow hydraulic system, depressurize the hydraulic reservoir AMM 29-14-00-614-001.
Replace the SEL VALVE-ALTN BRK [99GG] AMM 32-43-51-000-001 AMM 32-43-51-400-001.

(4) On the Yellow hydraulic system, pressurize the hydraulic reservoir AMM 29-14-00-614-002.

Use the Yellow electric pump to pressurize the Yellow-pressure brake accumulator (2582GM) to 206 bar (2988 psi) and stop the pump.

(5) If the fault continues:

Operate the manual depressurization pushbutton of the relief valve (3067GM) to release the accumulator pressure.
On the Yellow hydraulic system, depressurize the hydraulic reservoir AMM 29-14-00-614-001.
Replace the BRAKE RELIEF VALVE [3067GM] AMM 32-44-15-000-001 AMM 32-44-15-400-001.

(6) On the Yellow hydraulic system, pressurize the hydraulic reservoir AMM 29-14-00-614-002.

Use the Yellow electric pump to pressurize the Yellow-pressure brake accumulator (2582GM) to 206 bar (2988 psi) and stop the pump.

(7) If the fault continues, do a check of the Yellow-pressure brake accumulator (2582GM):

Operate the manual depressurization pushbutton of the relief valve (3067GM) to release the accumulator pressure.
On the Yellow hydraulic system, depressurize the hydraulic reservoir AMM 29-14-00-614-001.
On the Yellow-pressure brake accumulator (2582GM) release the nitrogen pressure.
Remove the Yellow-pressure brake accumulator (2582GM) AMM 32-44-11-000-001.
In the accumulator, on the nitrogen side, do a check for hydraulic fluid.

(a) If there is hydraulic fluid:

Collect and measure the volume of the hydraulic fluid.

1 If the volume of the hydraulic fluid is more than 100 cm3 (6.10 in.3):

Replace the ACCU-BRK YELLOW PRESS [2582GM] AMM 32-44-11-000-001 and AMM 32-44-11-400-001.

(b) If there is no hydraulic fluid or if the volume of the hydraulic fluid is less than 100 cm3 (6.10 in.3):

Replace the CHECK VALVE Y [3058GM] .
Install the Yellow-pressure brake accumulator (2582GM) AMM 32-44-11-400-001.
Inflate the accumulator with nitrogen AMM 12-14-32-614-002.
On the Yellow hydraulic system, pressurize the hydraulic reservoir AMM 29-14-00-614-002.
Use the Yellow electric pump to pressurize the Yellow-pressure brake accumulator (2582GM) to 206 bar (2988 psi) and stop the pump.

(8) If the fault continues:

Replace the HYDR. PRESSURE TRANSMITTER [3068GN] AMM 29-32-11-000-004 AMM 29-32-11-400-004.

(9) If the fault continues:

Replace the MANIFOLD [3016GM] AMM 32-44-17-000-001 AMM 32-44-17-400-001.

(10) If the fault continues:

Replace the ABCU [95GG] AMM 32-43-34-000-001 AMM 32-43-34-400-001.

[Rev.8 from Aug 2018] 2026.04.04 04:31:42 UTC