An actuator system for controlling a control surface of an aircraft, comprising: a control structure configured to define the control surface wherein the control structure has an axis of rotation about which the control structure can rotate relative to the aircraft; a first actuator assembly which has a first actuator arm; and a second actuator assembly which has a second actuator arm, wherein: the first actuator assembly and the second actuator assembly are spaced apart from one another along the axis of rotation; the first actuator assembly comprises a first cylinder member and a first piston positioned within the first cylinder member; the second actuator assembly comprises a second cylinder member and a second piston positioned within the second cylinder member; the first actuator arm is connected to the first cylinder member whereas the second actuator arm is connected to the second piston; and the first actuator arm is connected to a first band member and the first band member is connected to the control structure on a first side of the axis of rotation and the second actuator arm is connected to a second band member and the second band member is connected to the control structure on a second opposing side of the axis of rotation, when viewed in an actuation direction of the actuator assemblies (34, 38), crosswise to said axis of rotation. a control structure configured to define the control surface wherein the control structure has an axis of rotation about which the control structure can rotate relative to the aircraft; a first actuator assembly which has a first actuator arm; and a second actuator assembly which has a second actuator arm, wherein: the first actuator assembly and the second actuator assembly are spaced apart from one another along the axis of rotation; the first actuator assembly comprises a first cylinder member and a first piston positioned within the first cylinder member; the second actuator assembly comprises a second cylinder member and a second piston positioned within the second cylinder member; the first actuator arm is connected to the first cylinder member whereas the second actuator arm is connected to the second piston; and the first actuator arm is connected to a first band member and the first band member is connected to the control structure on a first side of the axis of rotation and the second actuator arm is connected to a second band member and the second band member is connected to the control structure on a second opposing side of the axis of rotation, when viewed in an actuation direction of the actuator assemblies (34, 38), crosswise to said axis of rotation. the first actuator assembly and the second actuator assembly are spaced apart from one another along the axis of rotation; the first actuator assembly comprises a first cylinder member and a first piston positioned within the first cylinder member; the second actuator assembly comprises a second cylinder member and a second piston positioned within the second cylinder member; the first actuator arm is connected to the first cylinder member whereas the second actuator arm is connected to the second piston; and the first actuator arm is connected to a first band member and the first band member is connected to the control structure on a first side of the axis of rotation and the second actuator arm is connected to a second band member and the second band member is connected to the control structure on a second opposing side of the axis of rotation, when viewed in an actuation direction of the actuator assemblies (34, 38), crosswise to said axis of rotation.