Hydraulic actuator and multi-cylinder hydraulic actuator system

A method for controlling an aircraft actuator system comprising an aircraft flight control surface and a multi-cylinder hydraulic actuator system for actuation of the aircraft flight control surface comprising multiple hydraulic actuators, each of the multiple hydraulic actuators being linked to others of the multiple hydraulic actuators via a simultaneous transmission line, each of the multiple hydraulic actuators comprising:

• a hydraulic cylinder;
• a piston within the hydraulic cylinder and movable in response to movement of hydraulic fluid in a hydraulic circuit coupled to the hydraulic cylinder;
• a synchronisation connection that is joined to or integral with the simultaneous transmission line and is for receiving an input from the simultaneous transmission line;
• and a valve for controlling the flow of hydraulic fluid in the hydraulic circuit;
• wherein the valve is a rotary valve comprising a first valve section and a second valve section wherein the rotary valve includes a resilient biasing mechanism between the first valve section and the second valve section, wherein the resilient biasing mechanism provides a torque acting to bias the relative position of the first valve section and the second valve section to a closed position;
• wherein the method comprises:
• rotating the first valve section in either a first rotational direction or a second rotational direction in response to input from the simultaneous transmission line in order to open a hydraulic flow path to the cylinder and urge the piston to move along the hydraulic cylinder in a corresponding first linear direction or second linear direction;
• and
• rotating the second valve section in the same rotational direction as the first valve section via a coupling between the second valve section and the piston, such that movement of the piston results in movement of the second valve section to follow the first valve section and to close the hydraulic flow path when the rotation of the first valve section is stopped.