The Westland Wessex was a gas turbine adaption of the piston powered S-58 Helicopter. A total of 356 were built in Britain between 1958 and 1970 and were used by the Royal Navy (RN) and the Royal Air Force (RAF). The Royal Australian Navy (RAN) purchased 27 helicopters in 1961 to be used in anti-submarine duties aboard the aircraft carriers HMAS Melbourne and HMAS Sydney. Shore basing followed until 1969 when they reverted to a General Duties role.
The Museum's Wessex was delivered to the RAN in 1962 and was retired from service in late 1989, it was allocated to the RMIT as an instructional airframe but remained unused, and ended up being donated to the Museum.