Failure of the BRK ALTN SERVOVALVE

TASK 32-43-00-810-825-A
Failure of the BRK ALTN SERVOVALVE

1. Possible Causes

SERVOVALVE-ALTN BRK, R [98GG]
PRESS XDCR-BRK, YELLOW R [100GG]
MANIFOLD-ALTN BRK, R [2852GM]
ABCU [95GG]
wiring

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 29-24-00-863-001	Pressurize the Yellow Hydraulic System with the Electric Pump
AMM 31-32-00-860-009	Procedure to Get Access to the SYSTEM REPORT/TEST/L/G Page
AMM 32-43-00-710-002	Operational Check to start the Functional Test of the Alternate Braking Automatically (flight simulated)
ASM 324303
AMM 32-43-32-000-001	Removal of the Alternate-Brake Manifold
AMM 32-43-32-400-001	Installation of the Alternate-Brake Manifold
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 32-43-35-000-001	Removal of the Alternate-Brake Direct Drive Valve
AMM 32-43-35-400-001	Installation of the Alternate-Brake Direct Drive Valve
AMM 32-44-19-000-001	Removal of the Pressure Transducer
AMM 32-44-19-400-001	Installation of the Pressure Transducer
TSM TASK 32-42-00-03	NORMAL BRAKING - TASK SUPPORTING DATA

3. Fault Confirmation
Subtask 32-43-00-740-068-A ** ON A/C NOT FOR ALL

A. Test
(1) Do the operational check to start the functional test of the Alternate Braking automatically (flight simulated) AMM 32-43-00-710-002.
(2) Read the TROUBLE SHOOTING DATA of the BSCU on the MCDU 32-42-00-03 TSM TASK 32-42-00-03.

4. Fault Isolation
Subtask 32-43-00-810-074-A ** ON A/C NOT FOR ALL

A. If the operational check gives the maintenance message BRK ALTN SERVOVLV (98GG)/ABCU (95GG) and the TROUBLE SHOOTING DATA gives the fault code 1521 or 1533:
(1) Do these steps:
(a) On the panel 400VU, make sure that the landing gear control lever is at down.
(b) Do a reset of the BSCU (10GG):

Set the A/SKID & N/W STRG switch to OFF then to ON.

(c) On the panel 110VU, make sure that the PARKING BRK control switch 73GG is at OFF.
(d) Pressurize the Yellow hydraulic system AMM 29-24-00-863-001.
(e) Set the PARKING BRK control switch 73GG to ON.
(f) On the MCDU, get the system SYSTEM REPORT/TEST/L/G Page AMM 31-32-00-860-009.
(g) On the system SYSTEM REPORT/TEST/L/G Page, push the line key adjacent to the BSCU CHAN 1 (2) indication.
(h) On the BSCU CHAN 1 (2) indication page, push the line key adjacent to the SPECIFIC DATA page 32-42-00-03 TSM TASK 32-42-00-03.
(i) On the BSCU CHAN 1 (2) SPECIFIC DATA page, push the line key adjacent to the SYSTEM DATA page.
(j) On the SYSTEM DATA page, push the line key adjacent to the REFRESH indication.
(k) Do a check of the Alternate Pressure Transducer Right (APTR) value page 1/3 32-42-00-03 TSM TASK 32-42-00-03.
(l) If the APTR pressure value is 145 +10 bar or -10 bar (2103.0467 +145.0377 psi or -145.0377 psi):

Replace the SERVOVALVE-ALTN BRK, R [98GG] AMM 32-43-35-000-001 AMM 32-43-35-400-001.

(m) If the APTR pressure value is not equal to 145 +10 bar or -10 bar (2103.0467 +145.0377 psi or -145.0377 psi):

Replace the PRESS XDCR-BRK, YELLOW R [100GG] AMM 32-44-19-000-001 AMM 32-44-19-400-001.

(2) If the fault continues:

Replace the MANIFOLD-ALTN BRK, R [2852GM] AMM 32-43-32-000-001 AMM 32-43-32-400-001.

(3) If the fault continues:

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

(4) If the fault continues:

Do a check and repair the wiring between the servovalve (98GG) and the ABCU (95GG) ASM 324303.

Subtask 32-43-00-740-069-A ** ON A/C NOT FOR ALL

B. Do the text given in para.3.A.

[Rev.8 from Aug 2018] 2026.04.04 04:31:41 UTC