The present disclosure provides an actuation system for a flight control surface of an aircraft, having: a support frame for supporting a flight control surface, the support frame being configured to be mounted to an airframe structure of the aircraft for movement between a first position and a second position to operate and move the control surface; an actuation mechanism configured to effect movement of the support frame between the second position and the first position; and a detection device for detecting a fault in the actuation mechanism, the detection device comprising a deflector configured to deflect or skew the support frame away from or out of the first position in the event of a fault in the actuation mechanism.