An actuator for at least one flight control surface of an aircraft. The actuator has at least two actuator members for actuating the flight control surface between two extreme positions and a motor connected to the actuator members by at least one rotary motion transmission line. Each actuator member includes a drive pinion and the actuator is arranged so that the transmission line has an angular amplitude of less than one revolution during movement of the flight control surface between its two positions. The motion transmission line is arranged to allow only one angular position between the drive pinions and the actuator member.