Jam tolerant electromechanical actuation systems and methods of operation

In an aircraft, having a fixed supporting structure and a control surface movable relative thereto, a jam tolerant actuating system including a computer, control means and at least two electromechanical actuator assemblies, each of said actuator assemblies further including a main motor for providing motion force therefore;

• a load sensor and a position sensor on said actuator assembly;
• a coupling/decoupling mechanism, positioned at the output member of said actuator assembly, for severing the load path between said actuator assembly and said movable surface;
• and a disconnect actuator for providing motive force for said coupling/decoupling mechanism, a method for controlling said actuating system, comprising the steps of:
• a. operating said movable control surface by said actuator assembly via said main motor, as directed by said computer via Command and Power inputs through said control means;
• b. relaying, from said control means to said computer, a plurality of the following inputs;
• i. main motor speed from a main motor commutator;
• ii. main motor current;
• iii. actuator assembly output load from said load sensor;
• and
• iv. actuator assembly output position, processed to determine speed, from said position sensor;
• and
• c. completely severing, via decoupling, the load path between said actuator assembly and said movable surface, via driving said coupling/decoupling mechanism in one direction, upon the detection of a malfunction, as determined by said control means, based on at least three of the above i., ii., iii., and iv. inputs;
• wherein the coupling/decoupling mechanism comprises a gear train which, and wherein said completely severing step comprises driving this gear train in the one direction, upon detection of the malfunction.