The 214ST was originally developed as a military project from the Bell 214B BigLifter, specifically for production in Iran and the development by Bell was funded by the Iranian government. The fundamental difference was the replacement of the Model 214's single Lycoming LTC-4 turboshaft engine with two General Electric T700 engines, to improve the helicopters hot and high performance and improve safety. An interim twin-engined conversion of a Model 214 flew on 15 February 1977 in Texas, Testing was successful, and Bell decided to press forward with a definitive twin engined Bell 214ST, with a fuselage stretched by and a revised main rotor of greater diameter. Iran changed its production plans, with 50 Bell 214A and 350 214STs to be built at the new production plant to be set up at Isfahan,