W DOC AIRBUS | TSM A320F

DFDR Inoperative

TASK 31-33-00-810-801-A
DFDR Inoperative

1. Possible Causes
  • DFDR [1TU]
  • wiring
2. Job Set-up Information
 A. Referenced Information
REFERENCE
DESIGNATION
AMM 31-33-00-710-001
Operational Test of the Power Interlocks and Status Monitoring
AMM 31-33-00-710-007
Operational Test of the DFDR
ASM 313301
AMM 31-33-55-000-001
Removal of the Digital Flight Data Recorder (DFDR)
AMM 31-33-55-400-002
Installation of the Digital Flight Data Recorder (DFDR)
3. Fault Confirmation
Subtask 31-33-00-710-050-A
A. Do the Operational Test of the Power Interlocks and Status Monitoring AMM 31-33-00-710-001.
4. Fault Isolation
Subtask 31-33-00-810-050-A ** ON A/C NOT FOR ALL
A. If the test gives the maintenance message DFDR:
  • make sure that the CB 7TU and 4RK are closed,
  • make sure that the ground control pushbutton is pushed on,
  • do a check for 115 VAC at the DFDR (1TU) connectors AA/1 and AA/2 ASM 313301.

   (1) If there is 115 VAC:

   (2) If the failure continues:
  • replace the relays 6RK, 8RK and 10RK.

NOTE: It is not neccesary to replace all the relays. You can replace only the one which is defect.
   (3) If the failure continues and if there is no 115 VAC:
  • do a check and repair the wiring as necessary ASM 313301, between:

    CB 7TU and relay 6RK A/B,

    CB 7TU and relay 8RK A/B,

    Relay 6RK pin A/4 and DFDR (1TU) connector AA/1,

    Relay 6RK pin A/X and relay 10RK pin A/X,

    Relay 8RK pin A/3 and relay 6RK pin A/4,

    Relay 8RK pin A/Z and relay 10RK pin A/B,

    DFDR ground pin AA/6 and ground,

    DFDR ground pin AA/21 and ground,

  • do a check for 28VDC at the relay 6RK, 8RK and 10RK pin A/X and A/Z ASM 313301.

   (4) If the failure continues check and repair the wiring as necessary ASM 313301 between:

DFDR (1TU) connector AA/23 and SDAC 1 (1WV1), SDAC 2 (1WV2) connector AA/9K,

DFDR (1TU) connector AA/7 and FDIU (2TU) connector AA/9J,

DFDR (1TU) connector AA/8 and FDIU (2TU) connector AA/9K,

DFDR (1TU) connector AA/9 and FDIU (2TU) connector AA/9E,

DFDR (1TU) connector AA/10 and FDIU (2TU) connector AA/9F.
Subtask 31-33-00-810-050-B ** ON A/C NOT FOR ALL
A. If the test gives the maintenance message DFDR:
  • make sure that the CB 5TV and 4RK are closed,
  • on the 21VU make sure that the RCDR GND CTL switch is on (the blue light indicator is on).
  • do a check for 115 VAC at the DFDR (1TU) connectors AA/1 and AA/2 ASM 313301.

   (1) If there is 115 VAC:
     (a) If necessary, do the operational test of the DFDR AMM 31-33-00-710-007.

   (2) If the failure continues:
  • replace the relays 6RK, 8RK and 10RK.

NOTE: It is not neccesary to replace all the relays. You can replace only the one which is defect.
   (3) If the failure continues and if there is no 115 VAC:
  • do a check and repair the wiring if necessary ASM 313301, between:

    CB 7TU and relay 6RK A/B,

    CB 7TU and relay 8RK A/B,

    Relay 6RK pin A/4 and DFDR (1TU) connector AA/1,

    Relay 6RK pin A/X and relay 10RK pin A/X,

    Relay 8RK pin A/3 and relay 6RK pin A/4,

    Relay 8RK pin A/Z and relay 10RK pin A/B,

    DFDR ground pin AA/6 and ground,

    DFDR ground pin AA/21 and ground,

  • do a check for 28VDC at the relay 6RK, 8RK and 10RK pin A/X and A/Z ASM 313301.

   (4) If the failure continues check and repair the wiring if necessary ASM 313301 between:

DFDR (1TU) connector AA/23 and SDAC 1 (1WV1), SDAC 2 (1WV2) connector AA/9K,

DFDR (1TU) connector AA/7 and FDIMU (10TV) connector AA/12G,

DFDR (1TU) connector AA/8 and FDIMU (10TV) connector AA/12H,

DFDR (1TU) connector AA/9 and FDIMU (10TV) connector AB/12G,

DFDR (1TU) connector AA/10 and FDIMU (10TV) connector AB/12H.
Subtask 31-33-00-710-057-A
B. Do the test given in paragraph 3.A. again to check the correct operation
(no maintenance message display).
[Rev.8 from Aug 2018] 2026.04.04 04:40:05 UTC
"AVIABRAIN" 2025