Loss of the Signal from the Yaw-Damper Position Transducer-Unit to the FAC 2

TASK 22-63-00-810-806-A
Loss of the Signal from the Yaw-Damper Position Transducer-Unit to the FAC 2

1. Possible Causes

FAC-2 [1CC2]
wiring of the 26VAC signal at RVDT box (2CC)
wiring of the ground signal at RVDT box (2CC)
XDCR UNIT-YAW DAMPER POS [2CC]
wirings of the YAW V1 MON and YAW V2 MON discretes (from the RVDT box (2CC) to the FAC 2 (1CC2)

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
AMM 22-63-00-710-001	Operational Test of the Yaw Damper Function
AMM 22-66-34-000-002	Removal of the FAC
AMM 22-66-34-400-002	Installation of the FAC
ASM 226804
AMM 22-96-00-710-001	Operational Test of the AFS
AMM 24-41-00-861-002	Energize the Aircraft Electrical Circuits from the External Power
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 29-10-00-863-003	Pressurize the Blue Hydraulic System with a Hydraulic Ground Power-Cart
AMM 29-23-00-863-001	Pressurize the Green Hydraulic System from the Yellow Hydraulic System through the PTU with the Electric Pump
AMM 29-24-00-863-001	Pressurize the Yellow Hydraulic System with the Electric Pump

3. Fault Confirmation

WARNING: MAKE SURE THAT ALL THE CIRCUITS IN MAINTENANCE ARE ISOLATED BEFORE YOU SUPPLY ELECTRICAL POWER TO THE AIRCRAFT.

WARNING: MAKE SURE THAT THE TRAVEL RANGES OF THE FLIGHT CONTROL SURFACES ARE CLEAR BEFORE YOU PRESSURIZE/DEPRESSURIZE A HYDRAULIC SYSTEM.

Subtask 22-63-00-860-053-A

A. Job Set-Up
(1) Aircraft Maintenance Configuration
(a) Energize the aircraft electrical circuits
AMM 24-41-00-861-002.
(b) Pressurize the aircraft hydraulic systems
AMM 29-23-00-863-001 AMM 29-24-00-863-001 AMM 29-10-00-863-003.

Subtask 22-63-00-865-053-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
121VU	AUTO FLT/FAC2/28VDC	5CC2	M19

Subtask 22-63-00-710-062-A

C. Test
(1) Open the circuit breaker 5CC2.
(2) After a minimum of 10 seconds, close the circuit breaker 5CC2.
(3) After 2 minutes, do the operational test of the AFS AMM 22-96-00-710-001 and read the result for the FAC 2.

4. Fault Isolation
Subtask 22-63-00-810-057-A

A. If the test gives the maintenance message AFS : FAC2/YD RVDT BOX 2CC:

replace the FAC-2 [1CC2] , AMM 22-66-34-000-002 and AMM 22-66-34-400-002.

(1) If the fault continues:

do a check of the wiring of the 26VAC signal at RVDT box (2CC) from pin B/A to the first terminal block ASM 226804.

(a) If there is no continuity:

repair the above wiring.

(b) If there is continuity:

do a check of the wiring of the ground signal at RVDT box (2CC) pin B/B ASM 226804.

1 If there is no continuity:

repair the above wiring.

2 If there is continuity:

replace the XDCR UNIT-YAW DAMPER POS [2CC] , AMM 27-26-17-000-001 and AMM 27-26-17-400-001.

(2) If the fault continues:

do a check and repair the wirings of the YAW V1 MON and YAW V2 MON discretes (from the RVDT box (2CC) to the FAC 2 (1CC2) ASM 226804.

Subtask 22-63-00-710-063-A

B. Do the operational test of the yaw damper function AMM 22-63-00-710-001.

[Rev.8 from Aug 2018] 2026.04.04 04:25:13 UTC