A helicopter autopilot system includes an inner loop for attitude hold for the flight of the helicopter including a given level of redundancy applied to the inner loop. An outer loop is configured for providing a navigation function with respect to the flight of the helicopter including a different level of redundancy than the inner loop. An actuator provides a braking force on a linkage that serves to stabilize the flight of the helicopter during a power failure. The actuator is electromechanical and receives electrical drive signals to provide automatic flight control of the helicopter without requiring a hydraulic assistance system in the helicopter. The autopilot can operate the helicopter in a failed mode of the hydraulic assistance system. A number of flight modes are described with associated sensor inputs including rate based and true attitude modes.

A redundant control system for a vehicle includes: one or more actuator housings; a plurality of actuator pistons coupled to the actuator housings, each of the actuator pistons mechanically coupled to one another and a common output device; a plurality of primary stages coupled to the actuator housings, each of the primary stages operatively coupled to move a respective actuator piston relative to at least one of the actuator housings, and each of the primary stages functioning independent of any other primary stage when the control system is operating in a flight-operation mode; and an auxiliary stage operatively coupled to move a first of the plurality of actuator pistons relative to at least one of the actuator housings when the control system is operating in a ground-operation mode, with each of the plurality of primary stages being responsive to movement of the first actuator piston by the auxiliary stage.

A redundant control system for a vehicle includes: one or more actuator housings; a plurality of actuator pistons coupled to the actuator housings, each of the actuator pistons mechanically coupled to one another and a common output device; a plurality of primary stages coupled to the actuator housings, each of the primary stages operatively coupled to move a respective actuator piston relative to at least one of the actuator housings, and each of the primary stages functioning independent of any other primary stage when the control system is operating in a flight-operation mode; and an auxiliary stage operatively coupled to move a first of the plurality of actuator pistons relative to at least one of the actuator housings when the control system is operating in a ground-operation mode, with each of the plurality of primary stages being responsive to movement of the first actuator piston by the auxiliary stage.

A power transfer unit includes a first hydraulic circuit, a second hydraulic circuit fluidly connected to the first hydraulic circuit, a pump and motor assembly fluidly connected between the first hydraulic circuit and the second hydraulic circuit, an isolation valve arranged along the first hydraulic circuit and fluidly connected to an inlet of the pump and motor assembly. The isolation valve is movable between a closed position and an open position to prevent and enable high-pressure fluid flow to the inlet, respectively. An unloader valve is arranged along the second hydraulic circuit and fluidly connected to an outlet of the pump and motor assembly, and an orifice is arranged along the second hydraulic circuit and fluidly connected to the unloader valve to reduce back pressure in the second hydraulic circuit.

A power transfer unit includes a first hydraulic circuit, a second hydraulic circuit fluidly connected to the first hydraulic circuit, a pump and motor assembly fluidly connected between the first hydraulic circuit and the second hydraulic circuit, an isolation valve arranged along the first hydraulic circuit and fluidly connected to an inlet of the pump and motor assembly. The isolation valve is movable between a closed position and an open position to prevent and enable high-pressure fluid flow to the inlet, respectively. An unloader valve is arranged along the second hydraulic circuit and fluidly connected to an outlet of the pump and motor assembly, and an orifice is arranged along the second hydraulic circuit and fluidly connected to the unloader valve to reduce back pressure in the second hydraulic circuit.

An actuation system for a control surface for an aircraft includes a first, second, third and fourth actuator, a first and second bell crank, and at least one push pull rod system. Each of the first and second bell cranks comprises a first and a second crank arm, the first and second crank arms intersect with and are joined to each other at an intersection, the first and second crank arms extend from the intersection at an angle to each other, the first bell crank is pivotally connected to the sub-structure by a first pivot extending through the first bell crank's intersection, and the second bell crank is pivotally connected to the sub-structure by a second pivot extending through the second bell crank's intersection.

A system and method for controlling two or more actuators acting together to move a component or surface includes Two or more actuators engaged with the component or surface to be moved. Each actuator is displaceable to move the component or surface in response to a component or surface position command. Each actuator has an associated actuator controller to receive the position command and to output an actuator displacement command. The system also includes force fight control means configured to determine a force differential from forces, or a pressure differential from pressures measured at each actuator and to derive a speed and/or a current offset signal, and to provide the offset signal to the actuator controllers to modify the actuator displacement commands.

Methods, apparatus, systems and articles of manufacture are disclosed for redundant actuation of control surfaces. An example apparatus includes a control surface of an aircraft, and an actuator to move the control surface. The example apparatus also includes an electric motor to move the actuator; the electric motor communicatively coupled to an electrical system of the aircraft. The example apparatus also includes a hydraulic motor to move the actuator, the hydraulic motor fluidly coupled to a hydraulic system of the aircraft. The example apparatus also includes a sensor to detect incorrect operation of the hydraulic system. The example apparatus also includes a switch operatively coupled to the sensor, the switch to enable operation of the electric motor in response to the detected incorrect operation of the hydraulic system.

A method for controlling a control surface multirod actuator arrangement and the arrangement including: a first and a second multirod actuator configured to move or clamp around a first set of piston rods; a third multirod actuator configured to move or clamp around a second set of piston rods; a control unit configured to control motion of the first set of piston rods in a first motion mode and to control motion of the second set of piston rods in a second motion mode. Steps are moving at least one piston rod of first set of piston rods and/or clamping in parked position at least one piston rod of the second set of piston rods.

A method for controlling a control surface multirod actuator arrangement and the arrangement including: a first and a second multirod actuator configured to move or clamp around a first set of piston rods; a third multirod actuator configured to move or clamp around a second set of piston rods; a control unit configured to control motion of the first set of piston rods in a first motion mode and to control motion of the second set of piston rods in a second motion mode. Steps are moving at least one piston rod of first set of piston rods and/or clamping in parked position at least one piston rod of the second set of piston rods.