Loss of One Analog Output of the Cabin Pressure Controller 1 to the SDAC 1

TASK 31-54-00-810-930-A
Loss of One Analog Output of the Cabin Pressure Controller 1 to the SDAC 1

1. Possible Causes

SDAC-1 [1WV1]
wiring
VALVE-OUTFLOW (10HL), FEEDBACK ASSEMBLY
OUTFLOW VALVE [10HL]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 21-31-51-000-001	Removal of the Outflow Valve (From Inside)
AMM 21-31-51-000-005	Removal of the Outflow Valve - Feedback Assembly 10HL-6
AMM 21-31-51-400-001	Installation of the Outflow Valve (From Inside)
AMM 21-31-51-400-005	Installation of the Outflow Valve - Feedback Assembly 10HL-6
AMM 31-50-00-710-001	Ground Scanning of the Central Warning System
ASM 315402
AMM 31-55-34-000-001	Removal of the SDAC
AMM 31-55-34-400-001	Installation of the SDAC

3. Fault Confirmation
Subtask 31-54-00-865-127-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	AIR COND/CAB/PRESS/CTL1	1HL	D09

Subtask 31-54-00-710-293-A

B. Test
Do the ground scanning of the central warning systems AMM 31-50-00-710-001.

4. Fault Isolation
Subtask 31-54-00-810-179-B

A. If the test gives the maintenance message:
SDAC1: NO CPC1 ANALOG SIGNAL

replace the SDAC-1 [1WV1] AMM 31-55-34-000-001 and AMM 31-55-34-400-001.

(1) If the fault continues:

do a check of the wiring from SDAC 1 (1WV1) pins AB/10C, 10D to the first terminal block ASM 315402.

(a) If there is no continuity:

repair the above wiring.

(b) If there is continuity:

do a check of the wiring from SDAC 1 (1WV1) pins AE/10E, 10F to the first terminal block ASM 315402.

1 If there is no continuity:

repair the above wiring.

2 If there is continuity:

do a check of the wiring from SDAC 1 (1WV1) pins AE/10G, 10H to the first terminal block ASM 315402.

a If there is no continuity:

repair the above wiring.

(2) If the fault continues
(a) replace the VALVE-OUTFLOW (10HL), FEEDBACK ASSEMBLY (if installed) AMM 21-31-51-000-005 and AMM 21-31-51-400-005.
(b) If the fault continues:

replace OUTFLOW VALVE [10HL] AMM 21-31-51-000-001 and AMM 21-31-51-400-001.

Subtask 31-54-00-710-294-A

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

[Rev.8 from Aug 2018] 2026.04.04 04:30:32 UTC