An actuator control arrangement comprising: a hydraulic actuator having a housing and a piston rod axially moveable within the housing between a neutral position, a retracted position and an extended position with respect to the housing in response to application of pressure to the piston rod; the arrangement further comprising a check valve moveable between a first position providing a flow path between a pressure source and the actuator, and a second position in which the flow path is closed off; and characterised by a mechanical link between the piston rod and the check valve, actuated in response to the piston rod passing a predetermined retracted position in a negative stroke direction, to set the check valve to the first position.

A system for detecting and controlling the position of a spoiler of an aircraft wing is described herein comprising: a hydraulic actuator having a piston rod operably connected to the spoiler, the piston rod being moveable between a retracted position, a neutral position and an extended position; and means for providing power to said hydraulic actuator; and a mechanical device for detecting whether the piston rod is in the retracted position, the neutral position or the extended position; and means, operatively connected to the mechanical device, that is configured to provide a change in a load applied to said hydraulic actuator, wherein said means is configured to change said load based on whether said piston rod is detected as being in said retracted position or said extended position.

Example methods and apparatus for mitigating aerodynamic flutter of aircraft wing flaps are disclosed. An example apparatus includes a fairing, an actuator, and a damper. The fairing is located on a bottom side of a wing of an aircraft. The actuator is disposed in the fairing. The actuator is coupled to and extends between the wing and a flap of the wing. The damper is disposed in the fairing. The damper is coupled to and extends between the fixed wing and the moveable flap.

Example methods and apparatus for mitigating aerodynamic flutter of aircraft wing flaps are disclosed. An example apparatus includes a fairing, an actuator, and a damper. The fairing is located on a bottom side of a wing of an aircraft. The actuator is disposed in the fairing. The actuator is coupled to and extends between the wing and a flap of the wing. The damper is disposed in the fairing. The damper is coupled to and extends between the fixed wing and the moveable flap.

A spoiler actuator can be operated by applying high pressure to a first chamber of the actuator on receipt of a command to extend the spoiler; applying high pressure to a second chamber of the actuator on receipt of a command to retract the spoiler; and on failure of a supply of the high pressure actuating an anti-extension valve to prevent extension of the spoiler; disengaging the anti-extension valve to permit extension if pressure applied to the anti-extension valve exceeds a predetermined force of a spring biasing the anti-extension valve to the engaged position, wherein additional force is applied to the anti-extension valve if the spoiler is retracted beyond a neutral position.

A spoiler actuator can be operated by applying high pressure to a first chamber of the actuator on receipt of a command to extend the spoiler; applying high pressure to a second chamber of the actuator on receipt of a command to retract the spoiler; and on failure of a supply of the high pressure actuating an anti-extension valve to prevent extension of the spoiler; disengaging the anti-extension valve to permit extension if pressure applied to the anti-extension valve exceeds a predetermined force of a spring biasing the anti-extension valve to the engaged position, wherein additional force is applied to the anti-extension valve if the spoiler is retracted beyond a neutral position.

Example methods and apparatus for mitigating aerodynamic flutter of aircraft wing flaps are disclosed. An example apparatus includes a fairing, an actuator, and a damper. The fairing is located on a bottom side of a wing of an aircraft. The actuator is disposed in the fairing. The actuator is coupled to and extends between the wing and a flap of the wing. The damper is disposed in the fairing. The damper is coupled to and extends between the fixed wing and the moveable flap.

Example methods and apparatus for mitigating aerodynamic flutter of aircraft wing flaps are disclosed. An example apparatus includes a fairing, an actuator, and a damper. The fairing is located on a bottom side of a wing of an aircraft. The actuator is disposed in the fairing. The actuator is coupled to and extends between the wing and a flap of the wing. The damper is disposed in the fairing. The damper is coupled to and extends between the fixed wing and the moveable flap.

An actuator control arrangement comprising: a hydraulic actuator having a housing and a piston rod axially moveable within the housing between a neutral position, a retracted position and an extended position with respect to the housing in response to application of pressure to the piston rod; the arrangement further comprising a check valve moveable between a first position providing a flow path between a pressure source and the actuator, and a second position in which the flow path is closed off; and characterised by a mechanical link between the piston rod and the check valve, actuated in response to the piston rod passing a predetermined retracted position in a negative stroke direction, to set the check valve to the first position.

A system for detecting and controlling the position of a spoiler of an aircraft wing is described herein comprising: a hydraulic actuator having a piston rod operably connected to the spoiler, the piston rod being moveable between a retracted position, a neutral position and an extended position; and means for providing power to said hydraulic actuator; and a mechanical device for detecting whether the piston rod is in the retracted position, the neutral position or the extended position; and means, operatively connected to the mechanical device, that is configured to provide a change in a load applied to said hydraulic actuator, wherein said means is configured to change said load based on whether said piston rod is detected as being in said retracted position or said extended position.