Optimized Requirements Verification for Flexible Drive Shafts

An optimized design, fabrication and testing solution is presented for flexible drive systems. A single piece welded drive shaft as well as a system consisting of sub and supercritical shafts, couplings and bearing hangers (for Tail Drive System in Helicopters and Interconnect Drive Systems in Tiltrotors) are included. This solution facilitates the qualification for flight of the drive shaft in airframes with reduced iron bird and expensive flight testing on the airframe. This solution also provides opportunities for improvements during the prototype phase such that potential deficiencies are identified and corrected before the drive shaft is put into service. An important part of the testing is accelerated testing, not in terms of operational life, but in terms of reliability. Theoretical Life of a flexible drive shaft is 'infinite' by design. 2.0