Boeing engine started in 1943 and Boeing's gas turbines were designated models 502 (T50), 520 (T60), 540, 551 and 553. Boeing built 2,461 engines before production ceased in April 1968. Many applications of the Boeing gas turbine engines were considered to be firsts, including the first turbine-powered helicopter and boat. Vertol Aircraft Corporation was acquired by Boeing in 1960, and was reorganized as Boeing's Vertol division. The twin-rotor CH-47 Chinook, produced by Vertol, took its first flight in 1961. This heavy-lift helicopter remains a work-horse vehicle to the present day. In 1964, Vertol also began production of the CH-46 Sea Knight.
1994 Scotland RAF Chinook crash data greatly reduced the amount and quality of data available to subsequent investigations. Information on speed and height were derived from the position of cockpit dials in the wreckage, and the wreckage's condition. During 1994, the RAF had begun to fit these recording devices across the Chinook HC.2 fleet prior to the accident; this process was completed in 2002. The aircraft had not been classified as being airworthy. It was mandated upon the RAF that it was "not to be relied upon in any way". The documentary series "Seconds From Disaster" featured the accident in the episode "Chinook Helicopter Crash".