DFDR Inoperative A320
1. Possible Causes:
-DFDR (1TU)
-DMU/FDIU (FDIMU) (10TV)
-wiring
2. Job Set-up Information
A. Referenced Information
| REFERENCE | DESIGNATION |
| Ref. AMM 31-33-00-710-001 | Operational Test of the Power Interlocks and Status Monitoring |
| Ref. AMM 31-33-00-710-007 | Operational Test of the DFDR |
| Ref. ASM 31-33-01 | |
| Ref. AMM 31-33-55-000-001 | Removal of the Digital Flight Data Recorder (DFDR) |
| Ref. AMM 31-33-55-400-002 | Installation of the Digital Flight Data Recorder (DFDR) |
| Ref. AMM 31-36-34-000-002 | Removal of the FDIU/DMU (FDIMU) |
| Ref. AMM 31-36-34-400-002 | Installation of the FDIU/DMU (FDIMU) |
3. Fault Confirmation
SUBTASK 31-33-00-710-050-A
A. Do the Operational Test of the Power Interlocks and Status Monitoring Ref. AMM 31-33-00-710-001.
4. Fault Isolation
SUBTASK 31-33-00-810-050-B
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 Ref. ASM 31-33-01.
(1) If there is 115 VAC:
(a) If necessary, do the operational test of the DFDR. Do not make the operational test of the DFDR in less than 5 minutes after power on Ref. AMM 31-33-00-710-007.
-replace the DFDR (1TU) Ref. AMM 31-33-55-000-001 and Ref. AMM 31-33-55-400-002.
(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 Ref. ASM 31-33-01, 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 Ref. ASM 31-33-01.
(4) If the failure continues check and repair the wiring if necessary Ref. ASM 31-33-01 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.
(5) If the failure continues:
— replace the DMU/FDIU (FDIMU) (10TV) Ref. AMM 31-36-34-000-002 and Ref. AMM 31-36-34-400-002.
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).
