Failure of the GPWC A320
1.Possible Causes:
-GPWC (1WZ)
-C/B-EIS/GPWS/115VAC (3WZ)
-short to ground at the wiring between the circuit breaker (3WZ) and the GPWC (1WZ)
2. Job Set-up Information
A. Referenced Information
| REFERENCE | DESIGNATION |
| Ref. AMM 34-48-00-740-002 | BITE Test of the Enhanced EGPWS |
| Ref. ASM 34-48-01 | |
| Ref. AMM 34-48-34-000-001 | Removal of the GPWC |
| Ref. AMM 34-48-34-400-001 | Installation of the GPWC |
3. Fault Confirmation
SUBTASK 34-48-00-865-050-A
A. Make sure that this(these) circuit breaker(s) is(are) closed:
| PANEL | DESIGNATION | FIN | LOCATION |
| 121VU | EIS/GPWS/115VAC | 3WZ | P07 |
SUBTASK 34-48-00-740-050-C
B. Test
(1) If the circuit breaker (3WZ) trips, refer to Para. 4. C. of this trouble shooting procedure.
(2) Do the BITE test of the Enhanced GPWS Ref. AMM 34-48-00-740-002.
— If the BITE test is not possible, refer to Para. 4. B. of this trouble shooting procedure.
4. Fault Isolation
SUBTASK 34-48-00-810-050-A
A. If the circuit breaker (3WZ) is closed, and if the BITE test gives the maintenance message GPWC (1WZ):
— replace the GPWC (1WZ) Ref. AMM 34-48-34-000-001 and Ref. AMM 34-48-34-400-001.
SUBTASK 34-48-00-810-051-A
B. If the circuit breaker (3WZ) is closed and if the BITE test is not possible
— do a check for 115VAC at pin AC/2 of the GPWC.
(1) If there is no 115VAC:
— do a check of the wiring of the 115VAC signal from circuit breaker (3WZ) to GPWC (1WZ) Ref. ASM 34-48-01.
(a) If there is no continuity:
— repair the above wiring.
(b) If there is continuity:
— replace the C/B-EIS/GPWS/115VAC (3WZ).
(2) If there is 115VAC:
— do a check of the wiring of the ground signal at GPWC pin AC/3.
(a) If there is no continuity:
— repair the above wiring.
SUBTASK 34-48-00-810-093-A
C. If the circuit breaker (3WZ) is open:
— close this circuit breaker.
(1) If the circuit breaker (3WZ) trips:
— remove the GPWC (1WZ) Ref. AMM 34-48-34-000-001.
— close the circuit breaker (3WZ).
(a) If this circuit breaker stays closed:
— install the GPWC Ref. AMM 34-48-34-400-001
1 If the circuit breaker trips again:
— replace the GPWC Ref. AMM 34-48-34-000-001 and Ref. AMM 34-48-34-400-001.
(b) If this circuit breaker trips again:
— do a check for a short to ground at the wiring between the circuit breaker (3WZ) and the GPWC (1WZ) Ref. ASM 34-48-01.
1 If there is a short to ground:
— repair the above wiring.
2 If there is no short to ground:
— replace the C/B-EIS/GPWS/115VAC (3WZ).
3 Install the GPWC Ref. AMM 34-48-34-400-001.
SUBTASK 34-48-00-740-051-A
D. Do the test given in Para. 3.B.
