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.
1978 Iranian Chinook shootdown damaged helicopter and opened fire with GSh-23L 23-mm gun, spending a total of 72 rounds in two passes and hitting the starboard engine of the CH-47C. The Iranian pilot was lucky enough to manage a landing near the Soviet border post at Gjaurs. All four crew members survived, but were subsequently captured by Soviet border guards. The remaining two Chinooks escaped, crossing back into Iranian airspace. Despite a severe loss of life for the IIAF, the incident was played down by both sides, and the Soviets subsequently permitted the damaged Chinook to be repaired by Iranians and flown back to