DOC AIRBUS | AMM A320FAILERON AND HYDRAULIC ACTUATION - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The hydraulic actuation is achieved by two electrohydraulic servocontrols for each aileron.
** ON A/C NOT FOR ALL The hydraulic actuation is achieved by two electrohydraulic servocontrols for each aileron.
2. Component Location
** ON A/C NOT FOR ALL 
Location of Aileron Servocontrols| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C ALL | |||||
| 33CE1 | SERVO CTL-L AILERON, INBD G | 575AT | 575 | 27-14-51 | |
| 33CE2 | SERVO CTL-R AILERON, INBD G | 675AT | 675 | 27-14-51 | |
| 33CE3 | SERVO CTL-L AILERON, OUTBD B | 575KB | 575 | 27-14-51 | |
| 33CE4 | SERVO CTL-R AILERON, OUTBD B | 675KB | 675 | 27-14-51 | |
3. Component Description
A. Aileron Servocontrol FIN: 33-CE-1 FIN: 33-CE-2 FIN: 33-CE-3 FIN: 33-CE-4
(1) General
The four fixed-body servocontrols (two per aileron) are interchangeable.
The four fixed-body servocontrols (two per aileron) are interchangeable.
A. Normal operation with the servocontrol pressurized
The pressurization of the servocontrol involves the opening of the pressure-line closing valve (2) and of the return-line closing valve (3). Thus, the servovalve (4) is supplied from the HP system and the return system of the servocontrol is connected to the LP system.
The pressurization of the servocontrol involves the opening of the pressure-line closing valve (2) and of the return-line closing valve (3). Thus, the servovalve (4) is supplied from the HP system and the return system of the servocontrol is connected to the LP system.
(1) Servocontrol in the active mode.
In this case, the solenoid valve (1) is energized and lets in the HP flow which puts the mode selector valve (5) in the active mode.
The two chambers of the actuator are thus connected to the servovalve control lines. The servocontrol is then in the active mode. The Linear Variable-Differential Transducer (LVDT) (11) supplies an electrical signal which identifies this change of state.
The feedback transducer (LVDT) (10) gives the servoloop feedback.
In this case, the solenoid valve (1) is energized and lets in the HP flow which puts the mode selector valve (5) in the active mode.
The two chambers of the actuator are thus connected to the servovalve control lines. The servocontrol is then in the active mode. The Linear Variable-Differential Transducer (LVDT) (11) supplies an electrical signal which identifies this change of state.
The feedback transducer (LVDT) (10) gives the servoloop feedback.
(2) Servocontrol in the damping mode.
In this configuration, the solenoid valve is de-energized and the mode selector-valve moves under the action of its spring. This causes the two chambers of the actuator to be interconnected through the damping orifice (6).
The linear variable-differential transformer identifies this change of state.
The check valve (7) and the fluid reserve (9) hold the volume of fluid in the actuator chambers :
In this configuration, the solenoid valve is de-energized and the mode selector-valve moves under the action of its spring. This causes the two chambers of the actuator to be interconnected through the damping orifice (6).
The linear variable-differential transformer identifies this change of state.
The check valve (7) and the fluid reserve (9) hold the volume of fluid in the actuator chambers :
- if the temperature of the hydraulic fluid changes
- if there is a leakage.
B. Operation after an electrical failure
In this case the solenoid valve is de-energized and the operation is identical to the one of paragraph A. (2).
In this case the solenoid valve is de-energized and the operation is identical to the one of paragraph A. (2).
C. Operation after a hydraulic failure
The closing valves (2) and (3) close and isolate the servocontrol from the hydraulic system of the aircraft.
If there is a rupture of the aircraft return line, the return relief valve holds the volume of fluid in the fluid reserve.
The mode selector valve moves under the action of its spring. Then the servocontrol operates in the damping mode.
The closing valves (2) and (3) close and isolate the servocontrol from the hydraulic system of the aircraft.
If there is a rupture of the aircraft return line, the return relief valve holds the volume of fluid in the fluid reserve.
The mode selector valve moves under the action of its spring. Then the servocontrol operates in the damping mode.
D. Special Case
After hydraulic depressurization, a difference in droop speed and travel between the two ailerons is possible.
This is because of the variations of friction in the attachments and the servo control.
This difference is correct.
After hydraulic depressurization, a difference in droop speed and travel between the two ailerons is possible.
This is because of the variations of friction in the attachments and the servo control.
This difference is correct.
E. Maintenance and rigging facilities
The maintenance is "on condition".
The items given below are Line Replaceable Units :
The maintenance is "on condition".
The items given below are Line Replaceable Units :
- filter
- servovalve
- solenoid valve
- linear variable-differential transducer.