Westland Wessex
 The Westland Wessex is a British-built turbine-powered development of the Sikorsky S-58 Choctaw it was developed and produced under license by Westland Aircraft (later Westland Helicopters). One of the main changes from Sikorsky's S-58 was the replacement of the piston-engine powerplant with a turboshaft engine; the Wessex was the first helicopter in the world to be produced in large numbers that made use of a gas turbine propulsion system.