DOC AIRBUS | TSM A320FLoss of the HMU Control through the two Channels on Engine 1
TASK 73-29-00-810-842-A
Loss of the HMU Control through the two Channels on Engine 1
1. Possible Causes
2. Job Set-up Information
A. Referenced Information
3. Fault Confirmation
Subtask 73-29-00-710-100-A ** ON A/C NOT FOR ALL
Subtask 73-29-00-810-104-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:35:56 UTC
Loss of the HMU 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 73-21-10-400-001 | 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 73-21-50-400-006 | Installation of the J7 Harness |
| AMM 73-21-50-400-007 | Installation of the J8 Harness |
| 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) |
Subtask 73-29-00-710-100-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.
(2) Read the TROUBLE SHOOTING DATA of the FADEC MENU on the MCDU (Ref. 70-00-00, P. Block 301).
4. Fault Isolation(1) Do the operational test of the FADEC 1A and 1B on the ground (with engine motoring) AMM 73-29-00-710-040.
(2) Read the TROUBLE SHOOTING DATA of the FADEC MENU on the MCDU (Ref. 70-00-00, P. Block 301).
Subtask 73-29-00-810-104-A ** ON A/C NOT FOR ALL
A. If the test gives the maintenance messages J7, HMU, ECU + J8, HMU, ECU and the TROUBLE SHOOTING DATA gives the complementary information VSV TORQUE MOTOR CURRENT:
Subtask 73-29-00-810-105-A ** ON A/C NOT FOR ALL - do a check for open or short to ground at pins J7/10, 25, 26 and J8/10, 25, 26 of the harnesses J7 and J8 from the ECU (4000KS) to the VSV torque motor in the HMU ASM 732518.
- repair the defective harness J7 or J8.
- disconnect the harnesses J7 and J8 from the ECU and do a check of the ECU cable resistance between:
. pins 25 and 26 (17 to 23 Ohms)
. pins 25 and 10 (> 10 Megohms)
. pin 25 and the ground (> 10 Megohms).
- replace the ECU [4000KS] , AMM 73-21-60-000-001 and AMM 73-21-60-400-001.
- disconnect the harnesses J7 and J8 from the HMU and do a resistance check of the HMU between:
. pins 25 and 26 (17 to 23 Ohms)
. pins 25 and 10 (> 10 Megohms)
. pin 25 and the ground (> 10 Megohms).
- replace the defective harness J7 , AMM 73-21-50-000-006 and AMM 73-21-50-400-006 or the defective harness J8 , AMM 73-21-50-000-007 and AMM 73-21-50-400-007.
- replace the HMU-1 [4000KC1] AMM 73-21-10-000-001 and AMM 73-21-10-400-001.
B. If the test gives the maintenance messages J7, HMU, ECU + J8, HMU, ECU and the TROUBLE SHOOTING DATA gives the complementary information VBV TORQUE MOTOR CURRENT:
Subtask 73-29-00-710-101-A ** ON A/C NOT FOR ALL - do a check for open or short to ground at pins J7/13, 29, 30 and J8/13, 29, 30 of the harnesses J7 and J8 from the ECU (4000KS) to the VBV torque-motor current in the HMU ASM 732518.
- repair the defective harness J7 or J8.
- disconnect the harnesses J7 and J8 from the ECU and do a check of the ECU cable resistance between:
. pins 29 and 30 (17 to 23 Ohms)
. pins 29 and 13 (> 10 Megohms)
. pin 29 and the ground (> 10 Megohms).
- replace the ECU [4000KS] , AMM 73-21-60-000-001 and AMM 73-21-60-400-001.
- disconnect the harnesses J7 and J8 from the HMU and do a resistance check of the HMU between:
. pins 29 and 30 (17 to 23 Ohms)
. pins 29 and 13 (> 10 Megohms)
. pin 29 and the ground (> 10 Megohms).
- replace the defective harness J7 , AMM 73-21-50-000-006 and AMM 73-21-50-400-006 or the defective harness J8 , AMM 73-21-50-000-007 and AMM 73-21-50-400-007.
- replace the HMU-1 [4000KC1] AMM 73-21-10-000-001 and AMM 73-21-10-400-001.
C. Do the test given in Para. 3.A.(1).