Embodiments include an apparatus comprising an aircraft wing and a trailing edge aerodynamic surface connected to a trailing edge of the aircraft wing via a piston assembly in which the piston assembly holds the trailing edge aerodynamic surface in a neutral position relative to the aircraft wing at a constant supply pressure. The piston assembly may be implemented using a pneumatic piston or a hydraulic piston. A first end of the piston assembly may be connected to the aircraft wing and a second end of the piston assembly may be connected to the trailing edge aerodynamic surface. The piston assembly may include a pressure relief valve which may open or close, raising or lowering the aerodynamic surface, responsive to lift load on the aircraft wing.

A hydraulic system for an aircraft having an engine and an auxiliary power unit includes a first hydraulic subsystem including a first hydraulic pump and a first set of hydraulic-powered components in fluid communication with the first hydraulic pump. The first hydraulic pump is powered by the engine to pump shared hydraulic fluid to the first set of hydraulic-powered components. The hydraulic system includes a second hydraulic subsystem including a second hydraulic pump and a second set of hydraulic-powered components in fluid communication with the second hydraulic pump. The second hydraulic pump is powered by the auxiliary power unit to pump the shared hydraulic fluid to the second set of hydraulic-powered components. A shared return line subsystem and reservoir is in fluid communication with the first and second hydraulic subsystems to return the shared hydraulic fluid to the first and second hydraulic pumps.

A hydraulic system for an aircraft having an engine and an auxiliary power unit includes a first hydraulic subsystem including a first hydraulic pump and a first set of hydraulic-powered components in fluid communication with the first hydraulic pump. The first hydraulic pump is powered by the engine to pump shared hydraulic fluid to the first set of hydraulic-powered components. The hydraulic system includes a second hydraulic subsystem including a second hydraulic pump and a second set of hydraulic-powered components in fluid communication with the second hydraulic pump. The second hydraulic pump is powered by the auxiliary power unit to pump the shared hydraulic fluid to the second set of hydraulic-powered components. A shared return line subsystem and reservoir is in fluid communication with the first and second hydraulic subsystems to return the shared hydraulic fluid to the first and second hydraulic pumps.

An actuator includes a plurality of linear motors. A carriage is operatively connected to each linear motor to be driven by each of the linear motors. An output forcer rod is operatively connected to at least one of the linear motors to be driven by at least one of the linear motors. A position sensor is operatively connected to the output forcer rod to measure motion of the output forcer rod. A fly-by-wire system includes a plurality of electromechanical actuators. Each electromechanical actuator includes a plurality of linear motors. A flight control computer is operatively connected to the linear motors of each of the electromechanical actuators. The fly-by-wire system includes a plurality of hydraulic systems. Each hydraulic system is operatively coupled to a respective one of the electromechanical actuators.

An actuator includes a plurality of linear motors. A carriage is operatively connected to each linear motor to be driven by each of the linear motors. An output forcer rod is operatively connected to at least one of the linear motors to be driven by at least one of the linear motors. A position sensor is operatively connected to the output forcer rod to measure motion of the output forcer rod. A fly-by-wire system includes a plurality of electromechanical actuators. Each electromechanical actuator includes a plurality of linear motors. A flight control computer is operatively connected to the linear motors of each of the electromechanical actuators. The fly-by-wire system includes a plurality of hydraulic systems. Each hydraulic system is operatively coupled to a respective one of the electromechanical actuators.

A control system may be used to control actuators that actuate movement of flight control surfaces of an aircraft. Each actuator is couplable to a flight control surface and includes a motion control assembly having a hydraulic motor and a drive path from the hydraulic motor to the flight control surface. Each hydraulic motor includes an extend port and a retract port. The system includes a hydraulic control module fluidly connected to the extend port and the retract port of each hydraulic motor and a controller operable to output hydraulic power from the hydraulic control module to the motion control assembly to actuate movement of the flight control surfaces. The controller is configured to identify an actuator that positionally leads the other actuators and reduce hydraulic power to the motion control assembly assigned to such actuator.

A control system may be used to control actuators that actuate movement of flight control surfaces of an aircraft. Each actuator is couplable to a flight control surface and includes a motion control assembly having a hydraulic motor and a drive path from the hydraulic motor to the flight control surface. Each hydraulic motor includes an extend port and a retract port. The system includes a hydraulic control module fluidly connected to the extend port and the retract port of each hydraulic motor and a controller operable to output hydraulic power from the hydraulic control module to the motion control assembly to actuate movement of the flight control surfaces. The controller is configured to identify an actuator that positionally leads the other actuators and reduce hydraulic power to the motion control assembly assigned to such actuator.

A rotary hydraulic actuator may be configured to output rotary motion to control a hinged surface of an aircraft. The actuator includes a nested ballscrew, ballnut, and output assembly that form concentric ball races for converting the linear motion and force of the linear actuator to rotary motion and torque of the output assembly that is connected to the hinged surface. One of the ball races is helically inclined and the other of the ball races is linear. The rotary hydraulic actuator may include a ball return structure that returns the balls from a loaded path of a ball race to an unloaded path of the ball race. The ball return structure may define a ball return path that is located at the same radial distance from the actuator centerline as the loaded path for minimizing the overall diameter of the actuator.

A rotary hydraulic actuator may be configured to output rotary motion to control a hinged surface of an aircraft. The actuator includes a nested ballscrew, ballnut, and output assembly that form concentric ball races for converting the linear motion and force of the linear actuator to rotary motion and torque of the output assembly that is connected to the hinged surface. One of the ball races is helically inclined and the other of the ball races is linear. The rotary hydraulic actuator may include a ball return structure that returns the balls from a loaded path of a ball race to an unloaded path of the ball race. The ball return structure may define a ball return path that is located at the same radial distance from the actuator centerline as the loaded path for minimizing the overall diameter of the actuator.

A fluid pressure valve according to an embodiment of the present invention is applicable to a fluid pressure servo mechanism. The fluid pressure valve includes a housing having a housing member, the housing member being formed integrally so as to have a first port, a second port, and a flow path connecting between the first port and the second port.