Example flap actuation systems and related methods are disclosed herein. An example flap actuation system includes a first actuator, a second actuator, a first drive arm coupled to the first actuator and to a flap, a second drive arm coupled to the second actuator and to the flap, a first cam, and a first output shaft. The first cam is to couple to the first drive to enable the first actuator to actuate the flap via the first drive arm. The example flap actuation system includes a second cam and a second output shaft. The first cam is to be uncoupled from the first drive arm in response to a failure of the first actuator. The second actuator is to actuate the flap via the first drive arm and the second drive arm in response to the failure of the first actuator.

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 screw (20) assembly for an actuator (10) is described comprising: a screw (20); a nut (22) threaded on said screw (20), such that rotation of said screw (20) causes axial movement of said nut (22); a stop located at an end of said screw (20) and defining an axial limit of said nut (22); a first feature located on said nut (22); and a second feature located on said stop; wherein said first and second features are configured to cooperate with one another substantially upon contact of said nut (22) with said stop so as to indicate an amount of free movement between said nut (22) and said screw (20).

An actuation system for a control surface of an aircraft includes a drive lever. The drive lever includes a coupling end configured to pivotably couple to a plurality of wing attach fittings and a lever end. The lever end includes a first actuator fitting configured to pivotably couple to a first actuator on a forward side of the drive lever; a second actuator fitting configured to pivotably couple to a second actuator on an aft side of the drive lever; a first drive link fitting configured to couple, via a first drive link, to a control surface of an aircraft; and a second drive link fitting configured to couple, via a second drive link, to the control surface of the aircraft.

An actuator for aviation may include an electromechanical drive unit connected with an output drive via a gearbox. The drive unit may have at least two partial drives that can be operated independently from one another. The gearbox may be located at least partially between the at least two partial drives such that the at least two partial drives are spaced apart from one another.

An upper attachment system for a trimmable horizontal stabiliser actuator (THSA) comprises: a housing, holding a yoke and a ballscrew; a nut coupled to the housing and cooperating with the ballscrew such that rotation of the ballscrew relative to the nut results in linear motion of the ballscrew; a recess formed between the yoke and the ballscrew and arranged to receive, in use, an upper part of a tie bar of the secondary load path of the actuator; and a biasing mechanism arranged such that, in use, when no axial load is applied to the tie bar, the yoke and the ballscrew are held by balanced forces from the biasing mechanism in a position within the recess.

A detection system for detecting failure in a primary load path of a flight control actuator and annunciating engagement in a secondary load path of the flight control actuator. The failure in the primary load path causes axial movement in a secondary rod of the secondary load path. The detection system includes a secondary mounting assembly that guides axial movement of the secondary rod; and a sensor that electronically detects relative axial displacement between the secondary rod and the secondary mounting assembly upon a primary load path failure and annunciates transition to engagement in the secondary load path.

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.

There is provided an actuator comprising screw shaft and a nut assembly. The nut assembly comprises a primary nut for transmitting load through the actuator along a primary load path, and a secondary nut for transmitting load through the actuator along a secondary load path. The secondary nut comprises first and second portions movable relative to one another. As load is transmitted through the actuator along the primary load path the secondary nut does not transmit load through the actuator, wherein upon failure of the primary load path the first and second portions move relative to each other, such relative movement causing the first and second portions to engage the screw shaft and enable transmittal of load through the secondary nut of the actuator along the secondary load path.

A linear actuator, for controlling movement of a control surface of an aircraft, includes a screw, a primary load path and secondary nut engaged with the screw, and an engagement member. The engagement member moves from an ambush position, maintained by the primary load path or the secondary nut, to an engaged position, restricting relative movement between the primary load path and the secondary nut. The restricted relative movement may occur in response to free relative axial movement of the primary load path and the secondary nut caused by a failure of the primary load path of the linear actuator. A sensor of the linear actuator is configured to sense the failure of the primary load path and the free relative axial movement of the primary load path and the secondary nut.