Failure of the TCAS A320
1.Possible Causes:
-CMPTR-TCAS (1SG)
-short to ground at the wiring between the circuit breaker (4SG) and the TCAS (1SG)
-C/B-NAV/TCAS
2. Job Set-up Information
A. Referenced Information
| REFERENCE | DESIGNATION |
| Ref. AMM 34-43-00-740-001 | BITE Test of the TCAS |
| Ref. ASM 34-43-01 | |
| Ref. AMM 34-43-34-000-001 | Removal of the TCAS Computer |
| Ref. AMM 34-43-34-400-001 | Installation of the TCAS Computer |
3. Fault Confirmation
SUBTASK 34-43-00-865-065-A
- A. Make sure that this(these) circuit breaker(s) is(are) closed:
| PANEL | DESIGNATION | FIN | LOCATION |
| 121VU | COM NAV/TCAS | 4SG | K10 |
SUBTASK 34-43-00-740-050-A
- B. Test
(1) If the circuit breaker (4SG) trips, refer to Para. 4. C. of this trouble shooting procedure.
(2) Do the BITE test of the TCAS Ref. AMM 34-43-00-740-001.
— If the BITE test is not possible, refer to Para. 4. B. of this trouble shooting procedure.
4. Fault Isolation
SUBTASK 34-43-00-810-050-A
- A. If the circuit breaker (4SG) is closed, and if the BITE test gives the maintenance message TCAS (1SG):
— replace the CMPTR-TCAS (1SG) Ref. AMM 34-43-34-000-001 and Ref. AMM 34-43-34-400-001.
SUBTASK 34-43-00-810-051-A
- B. If the circuit breaker (4SG) is closed and if the BITE test is not possible
— do a check for 115VAC at pin AC/1 of the TCAS.
(1) If there is no 115VAC:
— do a check of the wiring of the 115VAC signal from circuit breaker (4SG) to TCAS computer (1SG) Ref. ASM 34-43-01.
(a) If there is no continuity:
— repair the above wiring.
(b) If there is continuity:
— replace the C/B-NAV/TCAS (4SG).
(2) If there is 115VAC:
— do a check of the wiring of the ground signal at pin AC/7.
(a) If there is no continuity:
— repair the above wiring.
SUBTASK 34-43-00-810-079-F
- C. If the circuit breaker (4SG) is open:
— close this circuit breaker.
(1) If the circuit breaker (4SG) trips:
— disconnect the: CMPTR-TCAS (1SG) Ref. AMM 34-43-34-000-001
— close the circuit breaker (4SG).
(a) If this circuit breaker stays closed:
— replace the TCAS computer Ref. AMM 34-43-34-000-001 and Ref. AMM 34-43-34-400-001
(b) If this circuit breaker trips again:
— do a check for a short to ground at the wiring between the circuit breaker (4SG) and the TCAS (1SG) Ref. ASM 34-43-01.
1 If there is a short to ground:
— repair the above wiring.
2 If there is no short to ground:
— replace the C/B-NAV/TCAS.
3 Install the TCAS computer Ref. AMM 34-43-34-400-001
SUBTASK 34-43-00-740-051-A
D. Do the test given in Para. 3.
