Allison Model 250

Model 250 / T63
MTU-built Allison 250-C20B
Type Turboshaft/Turboprop
National origin United States
Manufacturer Allison Engine Company
Rolls-Royce plc
Major applications Bell 206
Britten-Norman BN-2T Turbine Islander
MD Helicopters MD 500
MBB Bo 105
Sikorsky S-76
Number built >30,000
Variants Rolls-Royce RR300
Developed into Rolls-Royce RR500

The Allison Model 250, now known as the Rolls-Royce M250, (US military designations T63 and T703) is a highly successful turboshaft engine family, originally developed by the Allison Engine Company in the early 1960s. The Model 250 has been produced by Rolls-Royce since it acquired Allison in 1995.