W DOC AIRBUS | TSM A320F

Loss of the Power Supply of the Engine 2 FDU (Loop B)

TASK 26-12-00-810-826-A
Loss of the Power Supply of the Engine 2 FDU (Loop B)

1. Possible Causes
  • FDU-ENG2 [2WD2]
  • wiring of the 28VDC signal from the circuit breaker 8WD2 to the engine 2 FDU
  • wiring of the ground signal at the engine 2 FDU
  • C/B-ENGINE/2/FIRE DET/LOOP B [8WD2]
  • ENG/APU FIRE PNL [1WD]
  • BOARD-ANN LT TEST & INTFC [5LP]
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
TSM TASK 24-00-00-810-803-A
Circuit Breaker Tripped and/or C/B TRIPPED Warning
AMM 26-12-00-710-002
Operational Test of the Engine Fire and Overheat Detection with the Centralized Fault Display System (CFDS)
ASM 261201
AMM 26-12-12-000-001
Removal of the ENG/APU Fire Panel
AMM 26-12-12-400-001
Installation of the ENG/APU Fire Panel
AMM 26-12-34-000-001
Removal of the Engine Fire-Detection Unit (FDU)
AMM 26-12-34-400-001
Installation of the Engine Fire-Detection Unit (FDU)
AMM 33-14-33-000-001
Removal of the Annunciator-Light Test and Interface-Board
AMM 33-14-33-400-001
Installation of the Annunciator-Light Test and Interface-Board
3. Fault Confirmation
Subtask 26-12-00-710-098-A
A. Test
   (1) Do the operational test of the engine fire and overheat detection from the Multipurpose Control and Display Unit (MCDU) AMM 26-12-00-710-002.
     (a) If the circuit breaker 8WD2 is open, refer to Para. 4.C.
4. Fault Isolation
Subtask 26-12-00-865-059-A
A. Table of the circuit breakers used in this procedure:
PANELDESIGNATIONFINLOCATION
** ON A/C ALL
49VUENGINE/2/FIRE DET/LOOP B8WD2A07
121VUENGINE/ENG2/FIRE DET/LOOP A7WD2Q39
Subtask 26-12-00-810-078-A ** ON A/C NOT FOR ALL
B. If the circuit breaker 8WD2 is closed, and if the test gives the maintenance message CHECK FDU ENG 2 SUPPLY:
  • do a check for 28VDC at the pin B/A of the engine 2 FDU.
   (1) If there is 28VDC:
   (2) If there is no 28VDC:
  • do a check of the wiring of the 28VDC signal from the circuit breaker 8WD2 to the engine 2 FDU ASM 261201.
     (a) If there is no continuity:
  • repair the above wiring.
     (b) If there is continuity:
  • do a check of the wiring of the ground signal at the engine 2 FDU pin B/B ASM 261201.
       1 If there is no continuity:
  • repair the above wiring.
       2 If there is continuity:
  • replace the C/B-ENGINE/2/FIRE DET/LOOP B [8WD2] .
Subtask 26-12-00-810-078-B ** ON A/C NOT FOR ALL
B. If the circuit breaker 8WD2 is closed, and if the test gives the maintenance message CHECK FDU ENG 2 CHAN B SUPPLY:
  • do a check for 28VDC at the pin B/A of the engine 2 FDU.
   (1) If there is 28VDC:
   (2) If there is no 28VDC:
  • do a check of the wiring of the 28VDC signal from the circuit breaker 8WD2 to the engine 2 FDU ASM 261201.
     (a) If there is no continuity:
  • repair the above wiring.
     (b) If there is continuity:
  • do a check of the wiring of the ground signal at the engine 2 FDU pin B/B ASM 261201.
       1 If there is no continuity:
  • repair the above wiring.
       2 If there is continuity:
  • replace the C/B-ENGINE/2/FIRE DET/LOOP B [8WD2] .
Subtask 26-12-00-810-079-A
C. If the circuit breaker (8WD2) is open:
   (1) If the fault continues:
  • disconnect the three units below:
    FDU-ENG2 [2WD2]
    ENG/APU FIRE PNL [1WD]
    BOARD-ANN LT TEST & INTFC [5LP]
  • close the C/B-ENGINE/2/FIRE DET/LOOP B [8WD2] .
     (a) If the circuit breaker stays closed:
       1 If the fault continues:
  • replace the C/B-ENGINE/2/FIRE DET/LOOP B [8WD2] .
   (2) Connect all the units.
Subtask 26-12-00-710-099-A
D. Do the test given in Para. 3.
[Rev.8 from Aug 2018] 2026.04.04 04:27:10 UTC
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