LOAD VARIABILITY OF A 2-BLADED HELICOPTER

A flight loads variability analysis program was conducted using the Be ll Model OH-58C helicopter. A representative flight consisting of 33 m aneuvers was repeated 30 times using six pilots (three from Bell Helic opter Textron and three from the Army) who flew the aircraft five time s each. The resulting data were analyzed statistically to determine th e parameters of distribution and variability using three different set s of data: peak loads, maneuver loads and total flight loads. In addit ion, the damage rates were also analyzed statistically. The results in dicate that the maximum oscillatory loads exhibit a larger variability than that obtained by analyzing either maneuver loads or the flight l oads and that the Weibull distribution can be used to represent the di stribution shapes of both the maneuver and flight loads. Assessment of load variability on a total flight basis reduces the complexity of re liability computations.