THE U.S. ARMY LEAD THE FLEET PROGRAM: A STRUCTURAL APPROACH TO PREDICTING HELICOPTER FAILURES

摘要

U.S. Army helicopters are extremely complex machines that are designed to perform within broad operational usage envelopes. The operational usage envelopes are defined by discrete flight regimes that consist of combinations of aircraft configurations and flight maneuvers. Each regime can occur in combination with varying values of engine torque, engine speed, and rotor speed. Army helicopter system and component scheduled maintenance, overhaul, and retirement actions typically are based upon calendar times and flight hours. These times are based upon a 'Composite Worst Case' (CWC) presumption of helicopter regime usage. CWC usage is derived for each U.S. Army helicopter model to capture the most severe usage that helicopter model can ever be expected to experience. Knowledge of actual operational usage can be used to identify unsafe usage, refine scheduled maintenance actions, and predict unscheduled maintenance requirements. The purpose of the Lead the Fleet (LTF) program is to gain better insight into the accumulated damage that each U.S. Army helicopter could experience during actual operational usage, and to use this knowledge to evaluate overhaul and retirement times, increase safety and operational readiness, and reduce costs. The LTF approach is to increase the flight hour rate and usage intensity of selected Army helicopters to identify safety, reliability, availability, and maintainability (RAM), and logistics issues before they occur during normal operational usage. In this manner, system and component deficiencies can be identified, addressed, and corrected prior to fleet wide requirements for costly restorations, modifications, or retrofits.