It is known to use rotary actuators to control the position of flight control surfaces on an aircraft. An example of a flight control surface is a spoiler, which is positioned on a trailing edge of an aircraft wing. The spoiler can be extended upwardly, from a stowed position flush to the wing to a raised position, to reduce the lift created by the wing. In order to connect the rotary output shaft to the flight control surface, it is common to use an elongate connecting rod.
In prior art rotary actuators, it is known to provide some sort of position sensor on the actuator output shaft to determine the angular displacement thereof, which in turn, allows the position of the flight control surface to be determined.