A Systematic Approach to Reducing UH-60M Tail Drive Shaft Maintenance

The Sikorsky Aircraft Corporation (SAC) and the U.S. Army Aviation Applied Technology Directorate (AATD) are jointly sponsoring the Capability-Based Operations and Sustainment Technology-Aviation (COST-A) program. The objective of COST-A is to demonstrate an integrated set of high-value diagnostics, prognostics, and system health management technologies that reduce the maintenance burden, without sacrificing safety, of six different rotorcraft systems, including the drive system. Project metrics include reductions in inspections/flight hour and maintenance labor/flight hour. One of the goals of the COST-A drive system portion of the effort is to develop a generalized approach to reduce the maintenance burden associated with helicopter tail drive shafts (TDS). Maintenance data and field experience suggests that TDS inspections are a significant contributor to maintenance man-hours (MMH). With this in mind, the approach described herein uses load history, vibration analysis, and physics-based models to detect failure mode drivers (misalignment, unbalance, and bolt preload loss) and predict the presence of different faults, including bolt-hole elongation and cracking, with a goal of providing the confidence necessary to extend or eliminate the more laborious portions of the current inspection methodology.