The Pratt & Whitney JT8D is a low-bypass (0.96 to 1) turbofan engine, introduced by Pratt & Whitney in February 1963 with the inaugural flight of Boeing's 727. It was a modification of the Pratt & Whitney J52 turbojet engine, which powered the US Navy A-6 Intruder attack aircraft. The Volvo RM8 is an afterburning version that was license-built in Sweden for the Saab 37 Viggen fighter. Pratt & Whitney also sells static versions for powerplant and ship propulsion as the FT8.