Loss of the Primary GPS Data on one ADIRU

TASK 34-14-00-810-972-A
Loss of the Primary GPS Data on one ADIRU

1. Possible Causes

wiring from the MMR1 to the ADIRU1
MMR-1 [40RT1]
wiring from the MMR2 to the ADIRU2
MMR-2 [40RT2]
wiring from the MMR1 to the ADIRU3

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
ASM 343601
ASM 343602
AMM 34-36-31-000-001	Removal of the ILS Receiver
AMM 34-36-31-400-001	Installation of the ILS Receiver

3. Fault Confirmation
Subtask 34-14-00-710-088-A ** ON A/C NOT FOR ALL

A. Not applicable, you cannot confirm this fault on the ground.

4. Fault Isolation
Subtask 34-14-00-810-228-C ** ON A/C NOT FOR ALL

A. If the STS - GNSSU 1 FLT message is shown on the ADIRS CDU (2FP) on the overhead panel 20VU:
(1) When the SYS OFF/1/3/2 selector switch is in the 1 position on the ADIRS CDU (20VU):

do a check and repair the wiring from the MMR1 to the ADIRU1 :
pins AB/2A, 2B to pins AB/14J, 15J ASM 343602.

(a) After the subsequent flight, if the fault continues:

replace the MMR-1 [40RT1] AMM 34-36-31-000-001 and AMM 34-36-31-400-001.

(2) When the SYS OFF/1/3/2 selector switch is in the 2 position on the ADIRS CDU (20VU):

do a check and repair the wiring from the MMR2 to the ADIRU2 :
pins AB/2A, 2B to pins AB/14J, 15J ASM 343602.

(a) After the subsequent flight, if the fault continues:

replace the MMR-2 [40RT2] AMM 34-36-31-000-001 and AMM 34-36-31-400-001.

(3) When the SYS OFF/1/3/2 selector switch is in the 3 position on the ADIRS CDU (20VU):

do a check and repair the wiring from the MMR1 to the ADIRU3 :
pins AB/7E, 7F to pins AB/14J, 15J ASM 343601.

(a) After the subsequent flight, if the fault continues:

replace the MMR-1 [40RT1] AMM 34-36-31-000-001 and AMM 34-36-31-400-001.

[Rev.8 from Aug 2018] 2026.04.04 04:32:53 UTC