W DOC AIRBUS | TSM A320F

APU Fuel Supply Failure

TASK 28-29-00-810-801-A
APU Fuel Supply Failure

1. Possible Causes
  • ACTUATOR-APU FUEL LP VALVE [3QF]
  • APU FUEL LP VALVE 14QM
  • RELAY 4KD
  • RELAY 5WF
  • RELAY 6WF
  • RELAY 6QC
  • Capacitor 74KD
  • Capacitor 76KD
  • Resistor 75KD
  • wiring
  • FUEL LINE VENT pushbutton switch
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
TSM TASK 28-29-00-810-802-A
APU Fuel LP Valve operates with one Motor only
ASM 262201
ASM 282201
AMM 28-29-00-710-001
Operational Test of the APU Low Pressure Fuel Valve using each individual Motor in turn
AMM 28-29-41-000-001
Removal of the APU Fuel Low-Pressure Valve
AMM 28-29-41-400-001
Installation of the APU Fuel Low-Pressure Valve
AMM 28-29-51-000-001
Removal of the APU Fuel LP Valve Actuator
AMM 28-29-51-400-001
Installation of the APU Fuel LP Valve Actuator
ASM 496100
ASM 496101
3. Fault Confirmation
Subtask 28-29-00-710-050-A
A. Do the operational test of the APU LP fuel-valve using each individual motor in turn AMM 28-29-00-710-001.
4. Fault Isolation
Subtask 28-29-00-810-050-B
A. If the test with both motors is not correct:
NOTE: When the actuator-APU fuel LP valve is removed, do a check of the APU fuel LP valve for correct function. If the function is not correct replace the APU FUEL LP VALVE 14QM AMM 28-29-41-000-001 and AMM 28-29-41-400-001.
   (1) If the fault continues:
  • do a check of the RELAY 4KD and replace if necessary.
   (2) If the fault continues:
  • do a check of the RELAY 5WF and replace if necessary.
   (3) If the fault continues:
  • do a check of the RELAY 6WF and replace if necessary.
   (4) If the fault continues:
  • do a check of the RELAY 6QC and replace if necessary.
   (5) If the fault continues:
NOTE: When the symptom were APU SHUT DOWN at the first start and the second start is OK.
  • do a check of the Capacitor 74KD , Capacitor 76KD , Resistor 75KD and replace if necessary.
    Use wiring ASM 496100 for FIN identification.
   (6) If the fault continues:
  • do a check and repair the wiring from the:
    CB 2KD to the APU MASTER SW 14KD via the RELAY 4KD,
    CB 3WF to the RELAY 5WF,
    RELAY 5WF to the GND,
    CB 4WF to the RELAY 6WF,
    RELAY 6WF to the GND,
    CB 3QC to the FUEL LINE VENT pushbutton switch 8QC ASM 496101, ASM 262201 and ASM 282201.
   (7) If the fault continues:
  • replace the FUEL LINE VENT pushbutton switch .
Subtask 28-29-00-810-051-A
B. If the test with one motor is not correct (Ref. TSM TASK 28-29-00-810-802).
Subtask 28-29-00-710-051-A
C. Do the test given in Para. 3.
5. Close-up
Subtask 28-29-00-860-050-A
A. Put the aircraft back to its initial configuration.
[Rev.8 from Aug 2018] 2026.04.04 04:28:53 UTC
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