W DOC AIRBUS | TSM A320F

APU Loop A and/or Loop B Fire Warning Signal Output

TASK 26-13-00-810-802-A
APU Loop A and/or Loop B Fire Warning Signal Output

1. Possible Causes
  • FDU-APU [13WG]
  • wiring
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
AMM 26-13-00-710-002
BITE Test of the APU Fire and Overheat Detection System
AWM 261302
AWM 261303
AMM 26-13-34-000-001
Removal of the APU Fire-Detection Unit (FDU)
AMM 26-13-34-400-001
Installation of the APU Fire-Detection Unit (FDU)
AWM 315218
3. Fault Confirmation
Subtask 26-13-00-710-051-A
A. Do the BITE test of the APU fire and overheat detection system AMM 26-13-00-710-002.
4. Fault Isolation
Subtask 26-13-00-810-064-A
A. If the test gives a different maintenance message:
  • Do the trouble shooting procedure related to the maintenance message.
Subtask 26-13-00-810-051-A
B. If the test gives the maintenance message:
CHECK FDU APU FIRE WARN CKT
and/or
CHECK FDU APU FIRE A WARN CKT
and/or
CHECK FDU APU FIRE B WARN CKT
   (1) If the fault continues:
     (a) Do a check and repair the wiring between:
  • FDU (13WG) connector A/E and connector 153VC pin 1,
  • Connector 153VC pin 1 and terminal block 1853VT/10E AWM 261302,
  • Terminal block 1853VT/10M and FWC-1 (1WW1) connector AA/5C,
  • Terminal block 1853VT/10N and FWC-2 (1WW2) connector AA/5C AWM 315218,

  • FDU (13WG) connector B/E and connector 153VC pin 4,
  • Connector 153VC pin4 and terminal block 1853VT/4A AWM 261302,
  • Terminal block 1853VT/4F and FWC-1 (1WW1) connector AD/5E,
  • Terminal block 1853VT/4G and FWC-2 (1WW2) connector AD/5E AWM 315218,

  • FDU (13WG) connector B/N and GND,
  • FDU (13WG) connector B/B and GND,
  • FDU (13WG) connector A/B and GND AWM 261302,

  • FDU (13WG) connector B/J and connector 2991VC pin 3,
  • Connector 2991VC pin 3 and APU fire detector loop-B (22WG) pin E,
  • FDU (13WG) connector B/K and connector 2991VC pin 4,
  • Connector 2991VC pin 4 and APU fire detector loop-B (22WG) pin A,

  • FDU (13WG) connector A/J and connector 2999VC pin 36,
  • Connector 2999VC pin 36 and APU fire detector loop-A (21WG) pin E,
  • FDU (13WG) connector A/K and connector 2999VC pin 37,
  • Connector 2999VC pin 37 and APU fire detector loop-A (21WG) pin A AWM 261303.
Subtask 26-13-00-710-054-A
C. Do the test as given in the Para. 3.A.
5. Close-up
Subtask 26-13-00-860-051-A
A. Put the aircraft back to its initial configuration.
[Rev.8 from Aug 2018] 2026.04.04 04:27:17 UTC
"WTRUIB" 2025