Loss of the Altitude Bus 2 of the RA Transceiver 1 Identified by the GPWS

TASK 34-42-00-810-813-A
Loss of the Altitude Bus 2 of the RA Transceiver 1 Identified by the GPWS

1. Possible Causes

XCVR-RA, 1 [2SA1]
wiring of the ALTITUDE BUS 2 from the RA transceiver 1 (2SA1) to the first terminal block

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
ASM 344201
AMM 34-42-33-000-001	Removal of the Radio Altimeter Transceiver
AMM 34-42-33-400-001	Installation of the Radio Altimeter Transceiver
AMM 34-48-00-740-002	BITE Test of the GPWS

3. Fault Confirmation
Subtask 34-42-00-865-062-A

A. Make sure that this(these) circuit breaker(s) is(are) closed:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
121VU	COM NAV/RAD ALTM/1	1SA1	K11

Subtask 34-42-00-740-066-C

B. Test
(1) Do the BITE test of the Enhanced GPWS AMM 34-48-00-740-002.

4. Fault Isolation
Subtask 34-42-00-810-064-A

A. If the test gives the maintenance message RA1 (1SA1)/GPWC (1WZ):

(1) If the fault continues:

do a check and repair the wiring of the ALTITUDE BUS 2 from the RA transceiver 1 (2SA1) to the first terminal block ASM 344201.

Subtask 34-42-00-740-067-A

B. Do the test given in Para. 3.B.

[Rev.8 from Aug 2018] 2026.04.04 04:33:08 UTC