Multi-fuseable shaft

A multi-fuseable shaft torque transfer assembly comprising:

• a first shear member having a predetermined torsional shear strength corresponding to a torsional shear weak point
• a second torsion member disposed axially concentric with respect to said shear tube and having a desired torsional yield strength, said torsional yield strength being less than the torsional shear strength of said first member;
• a pair of end coupling means mounted at opposite ends of said first and said second members for coupling said members to rotational drive and driven mechanical element;
• and
• means for connecting said end couplings to the ends of said shear member and said torsion member such that torque transmitted from one to the other of said end couplings, up to said torsional yield strength of said shear member is transmitted by said shear member.

A flight control surface actuation system for an aircraft having a plurality of symmetrical flight control surfaces, comprising

• at least one power drive unit;
• a plurality of actuators spaced along the length of each of said flight control surfaces, privotally connecting said flight control surfaces to said aircraft;
• a plurality of torque shafts interconnecting successively spaced actuators of said plurality of actuators;
• and
• means for connecting at least one power drive unit to said plurality of actuators and for inhibiting transmission of excessive torque by yielding in torsion at a specific threshold load and afterward maintaining a lower torque transmission capability with limited angular deflection for torque levels up to a substantial percentage of said threshold load.

A flight control surface actuation system for an aircraft having a plurality of symmetrical flight control surfaces, comprising:

• at least one power drive unit;
• a plurality of actuators spaced along the length of each of said flight control surfaces, privotally connecting said flight control surfaces to said aircraft;
• a plurality of torque shafts interconnecting successively spaced actuators of said plurality of actuators;
• a pair of rotational position sensors integral with each of said at least one power drive unit(s) to sense the angular position of the outputs of said power drive unit(s);
• a second set of rotational position transducers, one each proximate the most outboard of said plurality of actuators to sense the angular position of said actuator;
• an electronic control means, electrically connected to each of said rotaional position sensors, for shutting down power to said power drive unit upon detecting asymmetry between the angular position of said flight control surfaces driven by said power drive unit;
• a first member having a predetermined torsional shear strength;
• a second member having a desired torsional yield strength, said torsional yield strength being less than the torsional shear strength of said first member;
• a pair of end coupling means mounted at opposite ends of said first and said second members for coupling said members to rotational drive and driven mechanical element;
• and
• means for connecting said end couplings to the ends of said first member and said second member such that torque transmitted from one to the other of said end couplings, up to said torsional yield strength of said first member, is transmitted by said first member, said first member, said second member and said end couplings connecting said at least one power drive unit to said plurality of actuators and inhibiting transmission of excessive torque by yielding in torsion at a specific threshold load and afterward maintaining a significant torque transmission capability for a limited deflection.