Aileron servo
Active Mode
Activation of the unit requires power to the solenoid valve ( 1 ). This will cause the pressure line closing valve ( 2 ) and the return line closure valve ( 3 ) to open and the mode selector valve ( 5 ) will change to active position. The LVDT ( 11 ) supplies a signal identifying this position. The two chambers of the actuator are now connected to the servo valve ( 4 ), controlled by the ELAC. The feedback transducer ( 10 ) gives the servo loop feedback.
Damping Mode
The solenoid valve is deenergized. The mode selector valve moves to the re-laxed position by the spring. The two chambers are now interconnected through the damping orifice ( 6 ). In case of electrical failure the solenoid will deenergize and the unit goes to damping mode. In case of Ioss of hydraulic pressure the pressure and return line closing valve will close, causing the unit to revert to damping mode. The servo valve, solenoid valve and the mode selector valve are all LRU's. After replacement of the servo valve, adjustment of the feed back transducer is required. A adjustment device is located on the actuator piston end ( adjusting nut ).
Aileron Servo Valve
The aileron command from the ELAC is received by the servo control valve. The valve consist of a jet nozzle springloaded to the neutral position. The steering signal from the ELAC wiil activate the magnetic coil and reposition the jet nozzle sending the hydraulic pressure to one of the sides on the control sleeve. The control sleeve will guide the hydraulic pressure to either side of the aileron actuator and will connect the other side to return. Steering feed back signal to the ELAC is transmitted by the feedback trans-ducer located inside the aileron actuator