DOC AIRBUS | AMM A320FRUDDER HYDRAULIC ACTUATION - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
Three fixed-body servocontrols with mechanical input are used to hydraulically actuate the rudder.
Each servocontrol is powered by a different hydraulic system.
** ON A/C NOT FOR ALL Three fixed-body servocontrols with mechanical input are used to hydraulically actuate the rudder.
Each servocontrol is powered by a different hydraulic system.
2. Component Location
** ON A/C NOT FOR ALL 
Location of Rudder Servocontrols| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 1025GM | SERVO CTL-RUDDER, G | 325BL | 325 | 27-24-51 | |
| ** ON A/C NOT FOR ALL | |||||
| 1025GM | SERVO CTL-RUDDER, G | 325 | 27-24-51 | ||
| ** ON A/C NOT FOR ALL | |||||
| 2025GM | SERVO CTL-RUDDER, B | 325DL | 325 | 27-24-51 | |
| ** ON A/C NOT FOR ALL | |||||
| 2025GM | SERVO CTL-RUDDER, B | 325 | 27-24-51 | ||
| ** ON A/C NOT FOR ALL | |||||
| 3025GM | SERVO CTL-RUDDER, Y | 325CL | 325 | 27-24-51 | |
| ** ON A/C NOT FOR ALL | |||||
| 3025GM | SERVO CTL-RUDDER, Y | 325 | 27-24-51 | ||
3. Component Description
(1) General
The three servocontrols are interchangeable.
The three servocontrols are interchangeable.
4. Operation
A. Normal operation with the servocontrol pressurized
The moving piston rod of the servocontrol is slaved to the mechanical input signal via the input lever (10). This lever is hinged in the middle on the rotary input lever (11). It is connected at one end to the input rod and at the other end to the feedback rod (12).
The rotary lever (11) actuates the control valve (8) and the stops (1) limit its travel.
In the event of overpressure in one of the chambers, the chamber overpressure is applied against one of the two pistons (2) and/or (3).
It sets the damping and pressure-relief valve (5) to the bypass position.
Then the chambers are isolated from the control valve and connected via the damping hole (6).
The high pressure is connected to the return via the heating orifice (9).
This ensures permanent heating leakage.
The vent hole (13) serves to vent over or under pressure of air occurring in the internal chamber of the cylinder assy.
The moving piston rod of the servocontrol is slaved to the mechanical input signal via the input lever (10). This lever is hinged in the middle on the rotary input lever (11). It is connected at one end to the input rod and at the other end to the feedback rod (12).
The rotary lever (11) actuates the control valve (8) and the stops (1) limit its travel.
In the event of overpressure in one of the chambers, the chamber overpressure is applied against one of the two pistons (2) and/or (3).
It sets the damping and pressure-relief valve (5) to the bypass position.
Then the chambers are isolated from the control valve and connected via the damping hole (6).
The high pressure is connected to the return via the heating orifice (9).
This ensures permanent heating leakage.
The vent hole (13) serves to vent over or under pressure of air occurring in the internal chamber of the cylinder assy.
B. Operation on the ground with the servocontrol depressurized
When the servocontrol is depressurized, the spring (4) sets the damping and pressure-relief valve to the bypass position.
If the rudder is subjected to external forces, the pressure increases in one of the two chambers. This causes the movement of the servocontrol piston.
The fluid goes from one chamber to the other via the damping orifice and provides a ground gust-damping function for gust speeds up to 80 Kts.
Two anti-cavitation valves permit the suction of the necessary volume of hydraulic fluid to compensate for the thermal retraction on ground, in the damping mode.
When the servocontrol is depressurized, the spring (4) sets the damping and pressure-relief valve to the bypass position.
If the rudder is subjected to external forces, the pressure increases in one of the two chambers. This causes the movement of the servocontrol piston.
The fluid goes from one chamber to the other via the damping orifice and provides a ground gust-damping function for gust speeds up to 80 Kts.
Two anti-cavitation valves permit the suction of the necessary volume of hydraulic fluid to compensate for the thermal retraction on ground, in the damping mode.
C. Maintenance, rigging facilities, periodic tests
The maintenance is "On condition".
The items given below are Line-Replaceable Unit :
To this end, the adjustment of the servocontrol is obtained through the adjustment of the spring rod length.
The maintenance is "On condition".
The items given below are Line-Replaceable Unit :
- Filter
- Actuator eye-end.
Some servocontrols are fitted with a rod eye-end with a regreasable roller bearing. This roller bearing is lubricated through grease nipples.
To this end, the adjustment of the servocontrol is obtained through the adjustment of the spring rod length.
5. Test
A. A single operational periodic test is performed on the three hydraulic systems (through the use of leakage measurement valves).
Its purpose is to make sure that there is no valve jamming and no mechanical disconnection.
Its purpose is to make sure that there is no valve jamming and no mechanical disconnection.