In June 1958, Allison was awarded a contract by the Air Force (managing it for the Army) to design and develop the Model 250 (military designation T63) engine. Designed as both a turboshaft and turboprop, it was to be a simple, low-cost engine for several applications. A turboshaft version first ran in March 1959 and, after several major design iterations, the T63 received its military qualification and the civil Model 250 was type certificated in December 1962.
Early military helicopter applications included the Hughes OH-6A Cayuse and Bell OH-58A Kiowa; early commercial helicopters powered by the Model 250 included the Bell Model 206A JetRanger, Hughes Model 500, and Fairchild-Hiller FH-1100. Uprated versions dominated the light helicopter turbine engine market throughout the world for many years.
This Model 250-C28B is identical to the one that powered NASM's Bell 206 LongRanger "Spirit of Texas" helicopter that set an around-the-world record for helicopters in 1982.