W DOC AIRBUS | TSM A320F

Loss of the VBV Torque Motor Control - Engine 1 - Channel A

TASK 73-29-00-810-888-A
Loss of the VBV Torque Motor Control - Engine 1 - Channel A

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 73-21-50-000-040
Removal of the HJ7 Harness for SAC Engines
AMM 73-21-50-210-001
Visual Inspection of the Wiring Harness
AMM 73-21-50-210-002
Visual Inspection of the Wiring Harnesses
AMM 73-21-50-400-006
Installation of the J7 Harness
AMM 73-21-50-400-040
Installation of the HJ7 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)
AMM 73-29-00-710-040
Operational Test of the FADEC on the ground (with Engine Motoring)
3. Fault Confirmation
Subtask 73-29-00-710-192-A ** ON A/C NOT FOR ALL
A. Test
   (1) Do the operational test of the FADEC 1A on the ground (with engine non motoring) AMM 73-29-00-710-040.
4. Fault Isolation
Subtask 73-29-00-810-180-A ** ON A/C NOT FOR ALL
A. This fault is generated if there is an open or short to ground in the VBV torque motor current loop on channel A.
   (1) If the failure message J7, HMU(VBV TM), ECU is not confirmed:
  • no maintenance action is required.
   (2) If the failure message J7, HMU(VBV TM), ECU is not confirmed, but is repetitive:
     (a) If the fault continues during the subsequent flights:
     (b) If the fault continues during the subsequent flights:
   (3) If the failure message J7, HMU(VBV TM), ECU is confirmed:
     (a) Disconnect the J7 harness from the ECU (4000KS) receptacle.
       1 Visually examine the ECU (4000KS) receptacle and the J7 harness connector for damaged pins and contamination AMM 73-21-50-210-001.
         a If harness connector or ECU receptacle is damaged:
  • repair or replace as required.
         b If no damage is found:
  • do an electrical resistance test through the J7 harness between:
    . pins 29 and 30 (17 to 23 ohms)
    . pins 29 and 13 (> 10 megohms)
    . pin 29 and the ground (> 10 megohms).
         c If the resistance values are in the specified limits:
         d If the resistance values are out of the specified limits:
  • reconnect the J7 harness to the ECU (4000KS).
     (b) Disconnect the J7 harness from the HMU receptacle (HMU-A) (located in the left core compartment).
       1 Visually examine the J7 harness connector and the HMU receptacle for damaged pins and contamination AMM 73-21-50-210-001.
         a If harness connector or ECU receptacle is damaged:
  • repair or replace as required.
         b If no damage is found:
  • do an electrical resistance test through the HMU receptacle between:
    . pins 29 and 30 (17 to 23 ohms)
    . pins 29 and 13 (> 10 megohms)
    . pin 29 and the ground (> 10 megohms).
         c If the resistance values are out of the specified limits:
         d If the resistance values are in the specified limits:
Subtask 73-29-00-810-180-B ** ON A/C NOT FOR ALL
A. This fault is generated if there is an open or short to ground in the VBV torque motor current loop on channel A.
   (1) If the failure message J7, HMU(VBV TM), ECU is not confirmed:
  • no maintenance action is required.
   (2) If the failure message J7, HMU(VBV TM), ECU is not confirmed, but is repetitive:
     (a) If the fault continues during the subsequent flights:
     (b) If the fault continues during the subsequent flights:
   (3) If the failure message J7, HMU(VBV TM), ECU is confirmed:
     (a) Disconnect the HJ7 harness from the ECU (4000KS) receptacle.
       1 Visually examine the ECU (4000KS) receptacle and the HJ7 harness connector for damaged pins and contamination AMM 73-21-50-210-002.
         a If harness connector or ECU receptacle is damaged:
  • repair or replace as required.
         b If no damage is found:
  • do an electrical resistance test through the HJ7 harness between:
    . pins 29 and 30 (17 to 23 ohms)
    . pins 29 and 13 (> 10 megohms)
    . pin 29 and the ground (> 10 megohms).
         c If the resistance values are in the specified limits:
         d If the resistance values are out of the specified limits:
  • reconnect the HJ7 harness to the ECU (4000KS).
     (b) Disconnect the HJ7 harness from the HMU receptacle (HMU-A) (located in the left core compartment).
       1 Visually examine the HJ7 harness connector and the HMU receptacle for damaged pins and contamination AMM 73-21-50-210-002.
         a If harness connector or HMU receptacle is damaged:
  • repair or replace as required.
         b If no damage is found:
  • do an electrical resistance test through the HMU receptacle between:
    . pins 29 and 30 (17 to 23 ohms)
    . pins 29 and 13 (> 10 megohms).
    . pin 29 and the ground (> 10 megohms).
         c If the resistance values are out of the specified limits:
         d If the resistance values are in the specified limits:
Subtask 73-29-00-710-193-A ** ON A/C NOT FOR ALL
B. Do the test given in Para. 3.A.
   (1) No additional maintenance action is required if the fault is not confirmed.
   (2) Repeat the fault isolation procedure if the fault continues.
[Rev.8 from Aug 2018] 2026.04.04 04:41:04 UTC
"AVIABRAIN" 2025