Loss of Power Supply 26VAC of the Position Feedback Transducers Side 2

TASK 22-61-00-810-808-A
Loss of Power Supply 26VAC of the Position Feedback Transducers Side 2

1. Possible Causes

wiring of the 26VAC signal from the circuit breaker 14CC2 to the first terminal block
C/B-AUTO FLT/FAC2/26VAC [14CC2]
LIMITATION UNIT-RUDDER TRAVEL [4CC]
ACTUATOR-RUDDER TRIM [10CC]
SERVO ACTR-YAW DAMPER, 2 [3CC2]
XDCR UNIT-YAW DAMPER POS [2CC]
short to ground between the circuit breaker 14CC2 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 27-23-51-400-001	Installation 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 22-61-00-865-053-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
121VU	AUTO FLT/FAC2/26VAC	14CC2	M18

Subtask 22-61-00-710-066-A

B. Test
(1) Do the Ground Scanning of the AFS AMM 22-91-00-710-001.
(a) If the circuit breaker 14CC2 is open, refer to Para. 4.B.

4. Fault Isolation
Subtask 22-61-00-810-059-A

A. If the circuit breaker 14CC2 is closed, and if the test gives the maintenance message AFS: 231 XPA BUS BAR:

do a check of the wiring of the 26VAC signal from the circuit breaker 14CC2 to the first terminal block , ASM 226701.

(1) If there is no continuity:

(2) If there is continuity:

Subtask 22-61-00-810-061-A

B. If the circuit breaker 14CC2 is open:

(1) If this circuit breaker opens again:

disconnect these four units:
LIMITATION UNIT-RUDDER TRAVEL [4CC]
ACTUATOR-RUDDER TRIM [10CC]
SERVO ACTR-YAW DAMPER, 2 [3CC2]
XDCR UNIT-YAW DAMPER POS [2CC]
close the circuit breaker 14CC2.

(a) If this circuit breaker stays closed:

connect the units one by one until the circuit breaker 14CC2 opens again
replace the related unit:
for LRU 4CC: AMM 27-23-51-000-001 and AMM 27-23-51-400-001
for LRU 10CC: AMM 27-22-51-000-001 and AMM 27-22-51-400-001
for LRU 3CC2: AMM 27-26-51-000-001 and AMM 27-26-51-400-001
for LRU 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 14CC2 and the four units , ASM 226701.

1 If there is a short to ground:

2 If there is no short to ground:

(2) Connect all the units.

Subtask 22-61-00-710-067-A

C. Do the test given in Para. 3.

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