Loss of Power Supply 26VAC of the Position Feedback Transducers Side 1

TASK 22-61-00-810-807-A
Loss of Power Supply 26VAC of the Position Feedback Transducers Side 1

1. Possible Causes

Wiring of the 26VAC signal from the circuit breaker 14CC1 to the first terminal block
C/B-AUTO FLT/FAC1/26VAC [14CC1]
electronic module
LIMITATION UNIT-RUDDER TRAVEL [4CC]
ACTUATOR-RUDDER TRIM [10CC]
SERVO ACTR-YAW DAMPER, 1 [3CC1]
XDCR UNIT-YAW DAMPER POS [2CC]
Short to ground between the circuit breaker 14CC1 and the four units

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
ASM 226701
AMM 22-91-00-710-001	Ground Scanning of the AFS
AMM 27-22-51-000-001	Removal of the Rudder Trim Actuator
AMM 27-22-51-400-001	Installation of the Rudder Trim Actuator
AMM 27-23-51-000-001	Removal of the Rudder Travel Limitation Unit
AMM 27-23-51-000-002	Removal of the Electronic Module of the Rudder Travel Limitation Unit
AMM 27-23-51-400-001	Installation of the Rudder Travel-Limitation Unit
AMM 27-23-51-400-002	Installation of the Electronic Module of the Rudder Travel Limitation Unit
AMM 27-26-17-000-001	Removal of the Yaw Damper Position Transducer Unit
AMM 27-26-17-400-001	Installation of the Yaw Damper Position Transducer Unit
AMM 27-26-51-000-001	Removal of the Yaw Damper Servo Actuator
AMM 27-26-51-400-001	Installation of the Yaw Damper Servo Actuator

3. Fault Confirmation
Subtask 22-61-00-865-052-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	AUTO FLT/FAC1/26VAC	14CC1	B03

Subtask 22-61-00-710-064-A

B. Test
(1) Do the Ground Scanning of the AFS AMM 22-91-00-710-001.
(a) If the circuit breaker 14CC1 is open, refer to Para. 4.B.

4. Fault Isolation
Subtask 22-61-00-810-058-A

A. If the circuit breaker 14CC1 is closed, and if the test gives the maintenance message AFS: 431 XPA BUS BAR:

Do a check of the Wiring of the 26VAC signal from the circuit breaker 14CC1 to the first terminal block , ASM 226701.

(1) If there is no continuity:

Repair the above wiring.

(2) If there is continuity:

replace the C/B-AUTO FLT/FAC1/26VAC [14CC1] .

Subtask 22-61-00-810-060-A

B. If the circuit breaker 14CC1 is open:

Close this circuit breaker.

(1) If this circuit breaker opens again:

Disconnect these four units:
The rudder travel limitation unit (4CC)
The rudder trim actuator (10CC)
The yaw damper servo actuator 1 (3CC1)
The yaw damper position transducer unit (2CC).
Close the circuit breaker 14CC1.

(a) If this circuit breaker stays closed:

Connect the units one by one until the circuit breaker 14CC1 opens again.

NOTE: For the LRU 4CC, remove the electronic module before the connection. If the Circuit breaker (14CC1) remains closed, install the electronic module.

Replace the related units:
For LIMITATION UNIT-RUDDER TRAVEL [4CC] : AMM 27-23-51-000-001 and AMM 27-23-51-400-001
For electronic module of LIMITATION UNIT-RUDDER TRAVEL [4CC] : AMM 27-23-51-000-002 and AMM 27-23-51-400-002
For ACTUATOR-RUDDER TRIM [10CC] : AMM 27-22-51-000-001 and AMM 27-22-51-400-001
For SERVO ACTR-YAW DAMPER, 1 [3CC1] : AMM 27-26-51-000-001 and AMM 27-26-51-400-001
For XDCR UNIT-YAW DAMPER POS [2CC] : AMM 27-26-17-000-001 and AMM 27-26-17-400-001.

(b) If this circuit breaker opens again:

Do a check for a Short to ground between the circuit breaker 14CC1 and the four units , ASM 226701.

1 If there is a short to ground:

Repair the related wiring.

2 If there is no short to ground:

Replace the C/B-AUTO FLT/FAC1/26VAC [14CC1] .

(2) Connect all the units.

Subtask 22-61-00-710-065-A

C. Do the test given in Para. 3.

[Rev.8 from Aug 2018] 2026.04.04 04:25:11 UTC