Flight control mechanical backup system

Abstract

A robust mechanical reversion system which provides the ability to fly and land in the absence of any fly-by-wire controls and which is transparent to the pilot during normal operation. The described invention provides a mechanism which includes redundant linear variable differential transmitters (LVDT) which generates a transmitted signal in proportion to the displacement of the control apparatus in the cockpit. The signal is fed to the flight control computer which determines the magnitude of the change represented by the signal and in turn, commands both the control surface servo actuators as well as an electrical mechanical servo actuator (EMA) located in close proximity to the flight compartment and coupled to the mechanical system to move in proportion to the change. An Electromagnetic Actuator drives the disconnected mechanical system in synchronization with the position of the cockpit controls in the fly-by-wire mode for a given control surface each time the servo actuator(s) for the control surface are electrically commanded by the flight computer. This causes the mechanical system to remain in phase with the position of the control elements as if connected thereto. In the event of a failure of the fly-by-wire system the mechanical system is automatically coupled into the control system through locking actuators which release a coupling mechanism including a interlocking pin, locking cams, clutch or other engagement device and clamps or locks the pilots input to the mechanical control loop thus providing direct mechanical control to the surface actuators with very little transient effects.