The Allison Model 250 is a highly successful turboshaft engine family, originally developed by the Allison Engine Company in the early 1960s. Rolls-Royce has produced the Model 250 since it acquired A

The MD Helicopters MD 500 series is an American family of light utility civilian and military helicopters. The MD 500 was developed from the Hughes 500, a civilian version of the US Army's OH-6A Cayus