Establishing Rotorcraft Component Fatigue Lives using SUMS Data and a Partial Usage Spectrum Approach for the UH-60 L/M Blackhawk

Lives of fatigue critical components for Army aircraft are typically established based on component strength from ground test, loads for each regime from flight test, and aircraft usage in each regime from engineering and aircrew judgement. This paper documents the updates to the spectrum for the large Army UH-60 fleet based on usage monitored by the Integrated Vehicle Health Management System (IVHMS). IVHMS and subsequent post processing uses aircraft parameters to identify the regime at any given time. The recognized regimes are summed to generate a spectrum of time or occurrences in each regime. The Partial Regime Recognition Spectrum used here identified specific regimes that had a significant effect on part life and concentrated on identifying only those regimes. Time in other ‘unrecognized’ regimes was prorated based on the legacy spectrum. The SUMS system is validated using scripted flights, as well as by cross checking against a spectrum generated via pilot interviews. Six components were addressed with life changes ranging from 80% to 600% of the legacy life.