Loss of the HPTC Torque Motor Control through the two Channels on Engine 1

TASK 73-29-00-810-850-A
Loss of the HPTC Torque Motor Control through the two Channels on Engine 1

1. Possible Causes

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 73-21-10-000-001	Removal of the Hydromechanical Unit (HMU)
AMM 73-21-10-000-002	Removal of the Hydromechanical Unit (HMU)
AMM 73-21-10-400-001	Installation of the Hydromechanical Unit (HMU)
AMM 73-21-10-400-002	Installation of the Hydromechanical Unit (HMU)
AMM 73-21-50-000-006	Removal of J7 Harness
AMM 73-21-50-000-007	Removal of J8 Harness
AMM 73-21-50-000-040	Removal of the HJ7 Harness for SAC Engines
AMM 73-21-50-000-041	Removal of the HJ8 Harness for SAC Engines
AMM 73-21-50-400-006	Installation of the J7 Harness
AMM 73-21-50-400-007	Installation of the J8 Harness
AMM 73-21-50-400-040	Installation of the HJ7 Harness for SAC Engines
AMM 73-21-50-400-041	Installation of the HJ8 Harness for SAC Engines
AMM 73-21-60-000-001	Removal of the Electronic Control Unit (ECU)
AMM 73-21-60-400-001	Installation of the Electronic Control Unit (ECU)
ASM 732518
AMM 73-29-00-710-040	Operational Test of the FADEC on the ground (with Engine Motoring)

3. Fault Confirmation
Subtask 73-29-00-710-112-A ** ON A/C NOT FOR ALL

A. Test
(1) Do the operational test of the FADEC 1A and 1B on the ground (with engine motoring) AMM 73-29-00-710-040.

4. Fault Isolation
Subtask 73-29-00-810-140-A ** ON A/C NOT FOR ALL

A. If the test gives the maintenance messages J7, HMU (HPTCTM), ECU + J8, HMU (HPTCTM), ECU:

do a check for open or short to ground at pins J7/10, 23, 24 and J8/10, 23, 24 of the harnesses J7 and J8 between the ECU (4000KS) and the HPT torque-motor current in the HMU, ASM 732518.

(1) If one of these wirings is not correct:

(2) If these wirings are correct:

disconnect the harnesses J7 and J8 from the ECU and do a check of the ECU cable resistance between:
. pins 23 and 24 (17 to 23 Ohms)
. pins 23 and 10 (> 10 Megohms)
. pin 23 and the ground (> 10 Megohms).

(a) If the resistance values are in the specified limits:

(b) If the resistance values are out of the specified limits:

disconnect the harnesses J7 and J8 from the HMU and do a check of the HMU receptacle resistance between:
. pins 23 and 24 (17 to 23 Ohms)
. pins 23 and 10 (> 10 Megohms)
. pin 23 and the ground (> 10 Megohms).

1 If the resistance values are in the specified limits:

2 If the resistance values are out of the specified limits:

Subtask 73-29-00-810-140-B ** ON A/C NOT FOR ALL