Failure of the Tachometer (Wheel 1)

TASK 32-42-00-810-959-A
Failure of the Tachometer (Wheel 1)

1. Possible Causes

DRIVE ASSY-TACHOMETER,WHEEL 1 [2681GM]
TACHOMETER-WHEEL 1 [19GG]
wiring from the tachometer (19GG) pins A/A, C to the first terminal block

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 31-32-00-810-933-A	Failure of the Analog Links
ASM 279225
AMM 32-41-11-000-006	Removal of the MLG Wheel
AMM 32-41-11-400-006	Installation of the MLG Wheel
ASM 324202
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

3. Fault Confirmation
Subtask 32-42-00-720-092-A

A. Do this TSM task if three Class 3 fault occur and are found in less than one week.

4. Fault Isolation
Subtask 32-42-00-810-264-A

A. Remove the hubcap or the debris guard (if the brake fans are installed) AMM 32-41-11-000-006.
(1) Do a visual inspection of the tachometer drive mechanism and make sure that:

The tachometer drive shaft moves freely.
There is no deformation (twisting) and/or signs of friction on the drive shaft.
The splines of the tachometer drive shaft are in the correct condition.
The splines of the tachometer hubcap or the splines of the debris guard (if the brake fans are installed) are in the correct condition.

(2) If the tachometer drive is damaged:

Replace the DRIVE ASSY-TACHOMETER,WHEEL 1 [2681GM] AMM 32-42-68-000-003 and AMM 32-42-68-400-003.

(3) If the tachometer hubcap or the debris guard (if the brake fans are installed) is damaged:

Replace the tachometer hubcap or the debris guard (if the brake fans are installed) AMM 32-41-11-000-006.

(4) If the tachometer drive mechanism is not damaged:

Make sure that there is a layer of grease on the splines of the tachometer before the final assembly AMM 32-41-11-400-006.

(a) If the test confirms the fault:

Replace the TACHOMETER-WHEEL 1 [19GG] AMM 32-42-57-000-001 AMM 32-42-57-400-001.

(5) If the fault continues:

Do the trouble shooting procedure (Ref. TSM TASK 31-32-00-810-933) related to the ANI-6 analog input signal of SEC 2 COM and SEC 3 COM ASM 279225.

(6) If the fault continues:

Do a check and repair the wiring from the tachometer (19GG) pins A/A, C to the first terminal block ASM 324202.

[Rev.8 from Aug 2018] 2026.04.04 04:31:39 UTC