DOC AIRBUS | AMM A320FYAW DAMPER ACTUATION - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
Two electrohydraulic yaw damper servo-actuators under the control of the FACs (Ref. 22-61) are installed between the artificial feel and trim unit and the travel limitation unit (TLU). They drive the aft control via a differential linkage.
The yaw damper servo-actuator orders are added to those of the pilots up to the maximum travel that the TLU permits.
One of the two servo-actuators is active, the other remains in standby (bypass mode).
In the event of a double hydraulic failure, a centering spring rod sets the two yaw damper servo-actuators to the neutral position.
** ON A/C NOT FOR ALL Two electrohydraulic yaw damper servo-actuators under the control of the FACs (Ref. 22-61) are installed between the artificial feel and trim unit and the travel limitation unit (TLU). They drive the aft control via a differential linkage.
Yaw Damper Servo-Actuators - GeneralThe yaw damper servo-actuator orders are added to those of the pilots up to the maximum travel that the TLU permits.
One of the two servo-actuators is active, the other remains in standby (bypass mode).
In the event of a double hydraulic failure, a centering spring rod sets the two yaw damper servo-actuators to the neutral position.
2. Component Location
** ON A/C NOT FOR ALL | FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 3CC1 | SERVO ACTR-YAW DAMPER, 1 | 325BL | 325 | 27-26-51 | |
| 3CC2 | SERVO ACTR-YAW DAMPER, 2 | 325BR | 325 | 27-26-51 | |
3. Component Description
(1) General
The two electrohydraulic servo-actuators are interchangeable.
Each servo-actuator includes :
The two electrohydraulic servo-actuators are interchangeable.
Each servo-actuator includes :
- one piston with a transducer unit (LVDT) isolated from the hydraulic fluid
- one valve group which includes mainly :
one servovalve (2)
two solenoid valves (1)
two mode selector valves (3)
one pressure switch (5)
A. Normal operation with the actuator pressurized
The servo-actuator pressurization directly involves the supply of the servovalve (2) by the HP system.
The servo-actuator pressurization directly involves the supply of the servovalve (2) by the HP system.
(1) Yaw damper in the active mode
The two solenoid valves (1) must be energized to set the two selector valves (3) to the active mode ; i.e to connect the two piston chambers to the servovalve outputs.
Then, the servo-actuator is put in the active mode and the pressure switch (5) is not activated.
The feedback transducer (LVDT) (4) provides the servoloop feedback.
The two solenoid valves (1) must be energized to set the two selector valves (3) to the active mode ; i.e to connect the two piston chambers to the servovalve outputs.
Then, the servo-actuator is put in the active mode and the pressure switch (5) is not activated.
The feedback transducer (LVDT) (4) provides the servoloop feedback.
(2) Yaw damper in the bypass mode (standby configuration)
The two solenoid valves (1) are de-energized and the associated selector valves (3) are set to the bypass mode under the action of their spring.
This permits the interconnection of the two piston chambers. In this case, the pressure switch (5) is not activated.
The two solenoid valves (1) are de-energized and the associated selector valves (3) are set to the bypass mode under the action of their spring.
This permits the interconnection of the two piston chambers. In this case, the pressure switch (5) is not activated.
B. Operation in case of a simple electrical failure
One solenoid valve (1) is de-energized and the associated selector valve (3) is set to the bypass mode under the action of its spring.
But the pressure switch (5) is activated because the two selector valves are not in the same position.
One solenoid valve (1) is de-energized and the associated selector valve (3) is set to the bypass mode under the action of its spring.
But the pressure switch (5) is activated because the two selector valves are not in the same position.
C. Operation after a hydraulic failure
With no hydraulic pressure, the two selector valves (3) are set to the bypass mode under the action of their springs, thus the two chambers of the piston are interconnected.
In this case, the pressure switch (5) is not activated.
With no hydraulic pressure, the two selector valves (3) are set to the bypass mode under the action of their springs, thus the two chambers of the piston are interconnected.
In this case, the pressure switch (5) is not activated.
D. Maintenance and rigging facilities
The maintenance is "on condition".
The items below are Line Replaceable Units :
The maintenance is "on condition".
The items below are Line Replaceable Units :
- filter
- servovalve
- solenoid valves
- pressure switch