Brake Grabbing or Aircraft Pulsating Felt at Alternate/Normal Braking

TASK 32-42-00-810-912-A
Brake Grabbing or Aircraft Pulsating Felt at Alternate/Normal Braking

1. Possible Causes

BRAKE-WHEEL 2 [2641GM]
BRAKE-WHEEL 4 [2642GM]
BRAKE-WHEEL 1 [2643GM]
BRAKE-WHEEL 3 [2644GM]
bleeding of the related braking system
bleeding of the control system of the alternate braking with A/SKID
DRIVE ASSY-TACHOMETER,WHEEL 4 [2678GM]
DRIVE ASSY-TACHOMETER,WHEEL 3 [2679GM]
DRIVE ASSY-TACHOMETER,WHEEL 2 [2680GM]
DRIVE ASSY-TACHOMETER,WHEEL 1 [2681GM]
TACHOMETER-WHEEL 1 [19GG]
TACHOMETER-WHEEL 3 [20GG]
TACHOMETER-WHEEL 2 [21GG]
TACHOMETER-WHEEL 4 [22GG]
SERVOVALVE-NORM BRK WHEEL 1 [15GG]
SERVOVALVE-NORM BRK WHEEL 3 [16GG]
SERVOVALVE-NORM BRK WHEEL 2 [17GG]
SERVOVALVE-NORM BRK, WHEEL 4 [18GG]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 29-00-00-210-001	Check for Air in the Green/Blue/Yellow Hydraulic System
AMM 32-42-00-710-004	Operational Test of the Automatic Braking when the Landing Gear is retracted
AMM 32-42-00-870-001	Bleeding of the Normal Braking at the Brake Units
AMM 32-42-27-000-001	Removal of the Brake
AMM 32-42-27-210-001	Inspection/Check of the Brake with the Wheel Installed
AMM 32-42-27-400-001	Installation of the Brake
AMM 32-42-48-000-001	Removal of the Normal Brake Servovalve
AMM 32-42-48-400-001	Installation of the Normal Brake Servovalve
AMM 32-42-57-000-001	Removal of the Tachometer
AMM 32-42-57-400-001	Installation of the Tachometer
AMM 32-42-68-000-003	Removal of the MLG Tachometer-Drive
AMM 32-42-68-400-003	Installation of the MLG Tachometer-Drive
AMM 32-43-00-612-001	Filling and Bleeding of the Low Pressure Control System of the Alternate Braking
AMM 32-43-00-870-002	Bleeding of the High Pressure Alternate Braking System

3. Fault Confirmation
Subtask 32-42-00-710-078-A

A. Test
Not applicable

4. Fault Isolation
Subtask 32-42-00-810-176-A ** ON A/C NOT FOR ALL

A. Brake Grabbing or Pulsating Felt at Pedal Operation
(1) If you feel brake grabbing or pulsating when you operate the pedals:

Do a reset of the BSCU with the A/SKID & NOSE WHEEL switch (5GG).

(2) If the fault occurs immediately after the replacement of a normal-brake servovalve:

Do the operational test of the automatic braking when the landing gear is retracted to do a reset of the EEPROM of the BSCU AMM 32-42-00-710-004.

(3) If the fault continues:

Do an inspection/check of the brake AMM 32-42-27-210-001.

(a) If you find defect on the brake unit:

Replace the BRAKE-WHEEL 2 [2641GM] or BRAKE-WHEEL 4 [2642GM] or BRAKE-WHEEL 1 [2643GM] or BRAKE-WHEEL 3 [2644GM] AMM 32-42-27-000-001 and AMM 32-42-27-400-001.

(b) If you find no defect:

Do a check for air in the Green/Yellow hydraulic system AMM 29-00-00-210-001.
Do a bleeding of the related braking system AMM 32-42-00-870-001 or AMM 32-43-00-870-002.

(4) If the fault continues:

Do a bleeding of the control system of the alternate braking with A/SKID AMM 32-43-00-612-001.

(5) If the fault continues:

Do a check of the related tachometer drives for damage.

(a) If you find damage on one or more tachometer drives:

Replace the damaged drive(s):
DRIVE ASSY-TACHOMETER,WHEEL 4 [2678GM] or DRIVE ASSY-TACHOMETER,WHEEL 3 [2679GM] or DRIVE ASSY-TACHOMETER,WHEEL 2 [2680GM] or DRIVE ASSY-TACHOMETER,WHEEL 1 [2681GM] AMM 32-42-68-000-003 and AMM 32-42-68-400-003.

(b) If you find no damage on the tachometer drives:

Replace the related tachometer:
TACHOMETER-WHEEL 1 [19GG] or TACHOMETER-WHEEL 3 [20GG] or TACHOMETER-WHEEL 2 [21GG] or TACHOMETER-WHEEL 4 [22GG] AMM 32-42-57-000-001 and AMM 32-42-57-400-001.

(6) If the fault continues:

Replace the related servovalve:
SERVOVALVE-NORM BRK WHEEL 1 [15GG] or SERVOVALVE-NORM BRK WHEEL 3 [16GG] or SERVOVALVE-NORM BRK WHEEL 2 [17GG] or SERVOVALVE-NORM BRK, WHEEL 4 [18GG] AMM 32-42-48-000-001 and AMM 32-42-48-400-001.

(7) If the fault continues:

Do a check for air in the Green/Yellow hydraulic system AMM 29-00-00-210-001.
Do a bleeding of the related braking system AMM 32-42-00-870-001 or AMM 32-43-00-870-002.

NOTE: It is important to do the check for air and the bleeding of the brake system carefully to remove all the air from the hydraulic system.

Subtask 32-42-00-810-176-C ** ON A/C NOT FOR ALL