The Bell 206 is a helicopter family from the US manufacturer Bell Helicopters. The Bell 206 and its developments are still considered the most commercially successful civil helicopter to date. The Bell 206L LongRanger is an evolution of the Bell 206B JetRanger. The first prototypes were created in 1963, and the military variant, the Bell OH-58, became a standard helicopter for the US Army. The Bell 206 has been available on the civil market since 1967. The Bell 206L made its maiden flight on September 11, 1974. Unlike the JetRanger, the cabin was extended by 64 cm (notable by the three side windows instead of two) and a damping system was installed to reduce vibrations during flight. The Bell 206L-3 ST also features a second turbine, which is used during takeoff and landing as well as in emergencies.