Loss of the Yaw Damper Function on the FAC 1

TASK 22-63-00-810-801-A
Loss of the Yaw Damper Function on the FAC 1

1. Possible Causes

SERVO ACTR-YAW DAMPER, 1 [3CC1]
FAC-1 [1CC1]
SW-LOW OIL PRESS [4000EN]
SYSTEM-PRESS-SW [1151GN]
wiring of the YAW V1 COM and YAW V2 COM discretes (from the SERVO ACTR-YAW DAMPER, 1 (3CC1) to the FAC 1 (1CC1))
wiring of the servovalve of the SERVO ACTR-YAW DAMPER, 1 (3CC1)

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 22-91-00-710-001	Ground Scanning of the AFS
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 27-26-51-000-002	Removal of the Servovalve
AMM 27-26-51-000-003	Removal of the Solenoid Valve
AMM 27-26-51-000-004	Removal of the Pressure Switch
AMM 27-26-51-400-002	Installation of the Servovalve
AMM 27-26-51-400-003	Installation of the Solenoid Valve
AMM 27-26-51-400-004	Installation of the Pressure Switch
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
AMM 29-32-12-000-001	Removal of the System Pressure Switch
AMM 29-32-12-400-001	Installation of the System Pressure Switch
AMM 79-34-15-000-040	Removal of the Low Oil Pressure Switch
AMM 79-34-15-000-041	Removal of the Low Oil Pressure Switch
AMM 79-34-15-400-040	Installation of the Low Oil Pressure Switch
AMM 79-34-15-400-041	Installation of the Low Oil Pressure Switch

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.

CAUTION: DO NOT SWAP FLIGHT AUGMENTATION COMPUTERS. IF THERE IS A SHORT CIRCUIT, YOU WILL CAUSE DAMAGE TO A SERVICEABLE COMPUTER WHEN YOU SWAP THEM.

Subtask 22-63-00-860-050-A

A. Job Set-Up
(1) Aircraft Maintenance Configuration
(a) Energize the aircraft electrical circuits
AMM 24-41-00-861-002.

Subtask 22-63-00-865-050-A

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

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
49VU	AUTO FLT/FAC1/28VDC	5CC1	B04
49VU	AUTO FLT/FAC1/26VAC	14CC1	B03

Subtask 22-63-00-710-050-A

C. Test
(1) Open the circuit breaker 5CC1.
(2) After a minimum of 10 seconds, close the circuit breaker 5CC1.
(3) After 2 minutes:

Pressurize the aircraft hydraulic systems
AMM 29-23-00-863-001, AMM 29-24-00-863-001 and AMM 29-10-00-863-003,
After 1 minute, do the operational test of the Yaw Damper Function AMM 22-63-00-710-001,
Do the Ground Scanning of the AFS AMM 22-91-00-710-001.

4. Fault Isolation
Subtask 22-63-00-810-066-A ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message AFS: FAC1/YD ACTR1 3CC1, or if the ground scanning is not possible due to no AFS system response:

Open the circuit breakers 5CC1 and 14CC1,
Remove the FAC-1 (1CC1) AMM 22-66-34-000-002,
Do a check and repair the wiring between FAC-1 (1CC1) pin AF/4, AF/6 and SERVO ACTR-YAW DAMPER, 1 (3CC1) pin AE, AD ASM 226804,
Do a check and repair the wiring between FAC-1 (1CC1) pin AC/4, AC/6 and SERVO ACTR-YAW DAMPER, 1 (3CC1) pin BA, BB ASM 226804,
Do a check of the resistance between respectively:
. The pin AC/4 and the pin AC/6,
. Then the pin AF/4 and the pin AF/6 of the FAC-1 rack connector
ASM 226804.

NOTE: The resistance must be more than 40 Ohms.

(1) If the resistance is not correct:

Replace the faulty solenoid valve of the SERVO ACTR-YAW DAMPER, 1 [3CC1] AMM 27-26-51-000-003 and AMM 27-26-51-400-003,
Install the above removed FAC-1 (1CC1) AMM 22-66-34-400-002,
Close the circuit breakers 5CC1 and 14CC1.

(a) If the fault continues:

Replace the FAC-1 [1CC1] AMM 22-66-34-000-002 and AMM 22-66-34-400-002.

(2) If the resistance is correct:

Do a check and repair the wiring of the pressure switch of the SERVO ACTR-YAW DAMPER, 1 [3CC1] ASM 226804

(a) If the wiring is correct:

Replace the pressure switch of the SERVO ACTR-YAW DAMPER, 1 [3CC1] AMM 27-26-51-000-004 and AMM 27-26-51-400-004.

(3) If the fault continues:

Replace SW-LOW OIL PRESS [4000EN] of engine 1 AMM 79-34-15-000-040 and AMM 79-34-15-400-040.

(4) If the fault continues:

Do a check and repair the wiring of HYD CIRC PRESS SW (from the ENG-HYD PUMP-SW 1151GN) to FAC 1 (1CC1) ASM 226804.

(a) If the wiring is correct:

Replace SYSTEM-PRESS-SW [1151GN] AMM 29-32-12-000-001 and AMM 29-32-12-400-001.

(5) If the fault continues:

Do a check and repair the wiring of the YAW V1 COM and YAW V2 COM discretes (from the SERVO ACTR-YAW DAMPER, 1 (3CC1) to the FAC 1 (1CC1)) ASM 226804.

(a) If the wiring is correct:

Do a check and repair the wiring of the servovalve of the SERVO ACTR-YAW DAMPER, 1 (3CC1) ASM 226804.

1 If the wiring is correct:

Replace the servovalve of the SERVO ACTR-YAW DAMPER, 1 [3CC1] AMM 27-26-51-000-002 and AMM 27-26-51-400-002.

Subtask 22-63-00-810-066-B ** ON A/C NOT FOR ALL

DELETED

Subtask 22-63-00-810-066-D ** ON A/C NOT FOR ALL

A. If the test gives the maintenance message AFS: FAC1/YD ACTR1 3CC1, or if the ground scanning is not possible due to no AFS system response:

Open the circuit breakers 5CC1 and 14CC1,
Remove the FAC-1 (1CC1) AMM 22-66-34-000-002,
Do a check and repair the wiring between FAC-1 (1CC1) pin AF/4, AF/6 and SERVO ACTR-YAW DAMPER, 1 (3CC1) pin AE, AD ASM 226804,
Do a check and repair the wiring between FAC-1 (1CC1) pin AC/4, AC/6 and SERVO ACTR-YAW DAMPER, 1 (3CC1) pin BA, BB ASM 226804,
Do a check of the resistance between respectively:
. The pin AC/4 and the pin AC/6,
. Then the pin AF/4 and the pin AF/6 of the FAC-1 rack connector
ASM 226804.

NOTE: The resistance must be more than 40 Ohms.

(1) If the resistance is not correct:

Replace the faulty solenoid valve of the SERVO ACTR-YAW DAMPER, 1 [3CC1] AMM 27-26-51-000-003 and AMM 27-26-51-400-003,
Install the above removed FAC-1 (1CC1) AMM 22-66-34-400-002,
Close the circuit breakers 5CC1 and 14CC1.

(a) If the fault continues:

Replace the FAC-1 [1CC1] AMM 22-66-34-000-002 and AMM 22-66-34-400-002.

(2) If the resistance is correct:

Do a check and repair the wiring of the pressure switch of the SERVO ACTR-YAW DAMPER, 1 [3CC1] ASM 226804

(a) If the wiring is correct:

Replace the pressure switch of the SERVO ACTR-YAW DAMPER, 1 [3CC1] AMM 27-26-51-000-004 and AMM 27-26-51-400-004.

(3) If the fault continues:

Replace SW-LOW OIL PRESS [4000EN] of engine 1 AMM 79-34-15-000-041 and AMM 79-34-15-400-041.

(4) If the fault continues:

Do a check and repair the wiring of HYD CIRC PRESS SW (from the ENG-HYD PUMP-SW 1151GN) to FAC 1 (1CC1) ASM 226804.

(a) If the wiring is correct:

Replace SYSTEM-PRESS-SW [1151GN] AMM 29-32-12-000-001 and AMM 29-32-12-400-001.

(5) If the fault continues:

Do a check and repair the wiring of the YAW V1 COM and YAW V2 COM discretes (from the SERVO ACTR-YAW DAMPER, 1 (3CC1) to the FAC 1 (1CC1)) ASM 226804.

(a) If the wiring is correct:

Do a check and repair the wiring of the servovalve of the SERVO ACTR-YAW DAMPER, 1 (3CC1) ASM 226804.

1 If the wiring is correct:

Replace the servovalve of the SERVO ACTR-YAW DAMPER, 1 [3CC1] AMM 27-26-51-000-002 and AMM 27-26-51-400-002.

Subtask 22-63-00-810-051-A

B. If the yaw damper function is correct:

Do the operational test of the AFS AMM 22-96-00-710-001 and read the result for the FAC 1.

(1) If there is a message:

Do the trouble shooting procedure related to the maintenance message.

Subtask 22-63-00-710-052-A

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

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