W DOC AIRBUS | TSM A320F

APU AUTO SHUTDOWN - LOSS OF DC POWER, Power Supply Interrupt (131-9(A))

TASK 49-00-81-810-850-A
APU AUTO SHUTDOWN - LOSS OF DC POWER, Power Supply Interrupt (131-9(A))

1. Possible Causes
  • POWER SUPPLY INTERRUPT
  • ELECTRONIC CONTROL BOX [59KD]
  • RELAY-APU MAIN CTL [4KD]
  • P/BSW-APU/MASTER SW [14KD]
  • aircraft wiring
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
TSM TASK 24-00-00-810-802-A
Power Supply Interruption
AMM 24-41-00-861-002
Energize the Aircraft Electrical Circuits from the External Power
AMM 49-00-00-710-010
Operational Test of the APU
ASM 496101
AMM 49-61-34-000-003
Removal of the Electronic Control Box (ECB) (131-9(A))
AMM 49-61-34-400-003
Installation of the Electronic Control Box (ECB) (131-9(A))
3. Fault Confirmation
Subtask 49-00-81-710-190-A ** ON A/C NOT FOR ALL
A. Read-out of ECB Trouble-Shooting Data
   (1) Put the APU MASTER SW to the ON position.
   (2) Get access to the APU SHUTDOWN report.
   (3) Push the '>' adjacent to LRU DATA:
  • the MCDU menu shows
    POWER SUPPLY INTERRUPT

   (4) Energize the aircraft electrical circuits
AMM 24-41-00-861-002
   (5) Make sure that the 28VDC power supply of the APU BAT BUS (301PP) is correct at ASM 496101:
  • the pin 2 on the circuit breaker ECB SUPPLY (1KD),
  • the pin 2 on circuit breaker APU CTL (2KD).
     (a) If the power supply is not correct:
     (b) If the power supply is correct:
4. Fault Isolation
Subtask 49-00-81-810-131-A ** ON A/C NOT FOR ALL
A. If an APU auto shutdown occurs during the APU operation and the APU SHUTDOWN report gives the maintenance message:

LOSS OF DC POWER
POWER SUPPLY INTERRUPT

associated with Fault Code Numbers (FCN) 218

  • do a check of the ELECTRONIC CONTROL BOX [59KD] ASM 496101:
  • do a check for 28VDC at the ECB (59KD) AC/7.
NOTE: The APU MASTER SW PBS/W (14KD) on the panel 25VU must be in the ON position during the check.
   (1) If the power supply to the ECB (59KD) is not correct:
  • do a check and replace ASM 496101:
    - the RELAY-APU MAIN CTL [4KD] ,
    - the P/BSW-APU/MASTER SW [14KD] .
     (a) If the fault continues:
  • do a check and repair the aircraft wiring from
    the ECB (59KD) AC/3 to the ground,
    and
    the ECB (59KD) AC/7 to the circuit breaker MAIN SUPPLY (1KD) via the APU MAIN RELAY (4KD),
    and
    the ECB (59KD) AB/F9 to the circuit breaker APU CTL (2KD) via the APU MAIN RELAY (4KD),
    and
    the ECB (59KD) AB/F9 to the ground via the APU/MASTER SW PBS/W (14KD) A/A1.
    ASM 496101.
   (2) If the power supply to the ECB (59KD) is correct:
[Rev.8 from Aug 2018] 2026.04.04 04:34:35 UTC
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