W DOC AIRBUS | TSM A320F

Failure of the High Pressure Shut Off Valve Switch of the HMU on Engine 1

TASK 73-20-00-810-931-A
Failure of the High Pressure Shut Off Valve Switch of the HMU on Engine 1

1. Possible Causes
2. Job Set-up Information
 A. Fixtures, Tools, Test and Support Equipment
REFERENCE
QTY
DESIGNATION
No specific
AR
BRUSH - BRISTLED
 B. Consumable Materials
REFERENCE
DESIGNATION
(Material No.CP2011)
stoddard solvent
 C. Referenced Information
REFERENCE
DESIGNATION
AMM 71-00-00-710-002
Wet Motoring Check
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 73-21-50-210-001
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 73-21-50-400-007
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 73-20-00-710-250-A ** ON A/C NOT FOR ALL
A. Test
   (1) Do the Wet Motoring Check AMM 71-00-00-710-002.
   (2) Do the operational test of the FADEC 1B on the ground (with engine non motoring) AMM 73-29-00-710-040.
4. Fault Isolation
Subtask 73-20-00-810-201-A ** ON A/C NOT FOR ALL
A. If the CLASS 3 FAULTS page of the channel B gives the maintenance message J7, J8, HMU:
  • do a check for open or short to ground of the harnesses J7 and J8 between the ECU (4000KS) and the HMU pins J7 and J8/9, 22 to pins J7 and J8/9, 22 ASM 732518.
   (1) If one of these wirings is not correct:
  • repair the defective above wiring.
   (2) If these wirings are correct:
  • disconnect the cables J7 and J8 from the HMU.
  • install a jumper wire between the pins 9 and 22 on the cables J7 and J8.
  • disconnect the cables J7 and J8 from the ECU (4000KS).
  • do a visual inspection of the harness connector and receptacle. Look for contamination or oxidation or pins that have damage.
  • if you find damage, repair or replace as required.
  • clean the connector and receptacle with a BRUSH - BRISTLED and stoddard solvent (Material No.CP2011) AMM 73-21-50-210-001.
  • do a resistance check of the cable J7 then J8 at the ECU connectors between:
    . pins 9 and 22 (< 5 ohms)
    . pins 8 and 9 (> 10 megohms)
    . pins 9 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:
   (3) If the fault continues:
Subtask 73-20-00-810-201-B ** ON A/C NOT FOR ALL
A. If the test gives the maintenance message J7/J8, HMU (SOV SW) or J7/J8, HMU (SOV SW)*:
  • do a check for open or short to ground of the harnesses J7 and J8 between the ECU (4000KS) and the HMU pins J7 and J8/9, 22 to pins J7 and J8/9, 22 ASM 732518.
   (1) If one of these wirings is not correct:
  • repair the defective above wiring.
   (2) If these wirings are correct:
  • disconnect the cables J7 and J8 from the HMU.
  • install a jumper wire between the pins 9 and 22 on the cables J7 and J8.
  • disconnect the cables J7 and J8 from the ECU (4000KS).
  • do a visual inspection of the harness connector and receptacle. Look for contamination or oxidation or pins that have damage.
  • if you find damage, repair or replace as required.
  • clean the connector and receptacle with a BRUSH - BRISTLED and stoddard solvent (Material No.CP2011) AMM 73-21-50-210-002.
  • do a resistance check of the cable J7 then J8 at the ECU connectors between:
    . pins 9 and 22 (< 5 ohms)
    . pins 8 and 9 (> 10 megohms)
    . pins 9 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:
   (3) If the fault continues:
Subtask 73-20-00-810-201-C ** ON A/C NOT FOR ALL
A. If the test gives the maintenance message J7/J8, HMU (SOV SW)*:
  • do a check for open or short to ground of the harnesses J7 and J8 between the ECU (4000KS) and the HMU pins J7 and J8/9, 22 to pins J7 and J8/9, 22 ASM 732518.
   (1) If one of these wirings is not correct:
  • repair the defective above wiring.
   (2) If these wirings are correct:
  • disconnect the cables J7 and J8 from the HMU.
  • install a jumper wire between the pins 9 and 22 on the cables J7 and J8.
  • disconnect the cables J7 and J8 from the ECU (4000KS).
  • do a visual inspection of the harness connector and receptacle. Look for contamination or oxidation or pins that have damage.
  • if you find damage, repair or replace as required.
  • clean the connector and receptacle with a BRUSH - BRISTLED and stoddard solvent (Material No.CP2011) AMM 73-21-50-210-001.
  • do a resistance check of the cable J7 then J8 at the ECU connectors between:
    . pins 9 and 22 (< 5 ohms)
    . pins 8 and 9 (> 10 megohms)
    . pins 9 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:
   (3) If the fault continues:
[Rev.8 from Aug 2018] 2026.04.04 04:35:27 UTC
"WTRUIB" 2025