Originally developed by the American company Allison from 1958 onwards, the Model 250 is a free-turbine turboshaft engine designed for both small fixed-wing and rotary-wing aircraft. The first prototype, designated YT63 and bench-tested in 1959, provided the basis for numerous versions, including the 1974 C20B, which subsequently underwent continuous technical and performance development. Designed to offer a simple, compact and economical solution, the Model 250 is characterised by a modular construction that allows the main engine assemblies to be serviced separately, reducing maintenance time. Its high reliability, favourable power-to-weight ratio and ease of installation have contributed to its international success. Produced in tens of thousands of units, the Model 250 has been adopted for numerous aircraft, becoming one of the most widely used engines in the history of light aviation. The C20B version is still used today in MD Helicopters 500 series helicopters and was widely installed in the Bell 206B JetRanger and its corresponding models manufactured under licence in Italy by Agusta. These helicopters were operated by civilian organisations, the Armed Forces and law-enforcement agencies. The engine on display comes from an Agusta-Bell AB 206B operated by the Italian State Police, which donated it to the Museum of Engines in 2026.
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Used in various helicopters such as MD Helicopters 500, Bell 206B JetRanger, Agusta-Bell AB 206B, Messerschmitt-Bölkow-Blohm Bo 105.
Kind donation of the Italian State Police.
