Aircraft typically include a plurality of flight control surfaces that, when controllably positioned, guide the movement of the aircraft from one destination to another. The number and type of flight control surfaces included in an aircraft may vary, but typically include both primary flight control surfaces and secondary flight control surfaces. The primary flight control surfaces are those that are used to control aircraft movement in the pitch, yaw, and roll axes, and the secondary flight control surfaces are those that are used to influence the lift or drag (or both) of the aircraft. Although some aircraft may include additional control surfaces, the primary flight control surfaces typically include a pair of elevators, a rudder, and a pair of ailerons, and the secondary flight control surfaces typically include a plurality of flaps, slats, and spoilers.
The positions of the aircraft flight control surfaces are typically controlled using a flight control surface actuation system. The flight control surface actuation system, in response to position commands that originate from either the flight crew or an aircraft autopilot, moves the aircraft flight control surfaces to the commanded positions. In most instances, this movement is effected via actuators that are coupled to the flight control surfaces. Though unlikely, it is postulated that a flight control surface actuator could become inoperable. Thus, some flight control surface actuation systems are implemented with a plurality of actuators coupled to a single flight control surface.
In many flight control surface actuation systems the actuators are hydraulically powered. Some flight control surface actuation systems have been implemented, however, with other types of actuators, including pneumatic and electromechanical actuators. Additionally, in some flight control surface actuation systems, a portion of the actuators, such as those that are used to drive the flaps and slats, are driven via one or more central drive units and mechanical drive trains.
Although the flight control surface actuation systems that include hydraulic, pneumatic, and/or electromechanical actuators are generally safe, reliable, and robust, these systems do suffer certain drawbacks. Namely, these systems can be relatively complex, can involve the use of numerous parts, can be relatively heavy, and may not be easily implemented to provide sufficient redundancy, fault isolation, and/or system monitoring.
Hence, there is a need for a flight control surface actuation system that is less complex and/or is lighter than known systems and/or provides sufficient redundancy, fault isolation, and monitoring. The present invention addresses one or more of these needs.