The Bell 204 and 205 are the civilian versions of the UH-1 Iroquois single-engine military helicopter of the Huey family of helicopters. They are type-certificated in the transport category and are used in a wide variety of applications, including crop dusting, cargo lifting and aerial firefighting. Development Bell designed its Model 204 in response to a 1955 United States Army requirement for a utility helicopter. The 204 was a giant step forward in helicopter design, being one of the first to be powered by a turboshaft. The turboshaft engine radically improved the practicality of the helicopter due to its light weight and high power-to-weight ratio, lower fuel consumption, and lower maintenance and operating costs. The use of a turboshaft in the 204 allowed it to carry a useful payload over respectable ranges and at reasonable speeds, which resulted in the 204 and subsequent 205 becoming the most successful western helicopter series in terms of numbers built. The civil 204B was first delivered in 1961. The subsequent Model 205A-1 is equivalent to the UH-1H, which, compared to the 204, is longer, larger, and has better performance and a more powerful engine. Over 60 civil Model 204B helicopters had been delivered by 1967, while further examples were built by Agusta-Bell until 1973. 12,000 Model 205s (including civil 205A-1s) were built by Bell and Agusta-Bell up to the early 1980s. Numerous ex-military 204s and 205s were converted for commercial use. Variants Bell 204 Bell Helicopter's company designation of the UH-1B. Bell 204B – Civil or military utility transport helicopter, derived from the UH-1B. Powered by a T53-09A, max weight was 8,500 lbs, max passengers, ten. Agusta 204B – Civil or military utility transport helicopter. Built under licence in Italy by Agusta in 1963–1967. Also known as Agusta-Bell AB 204 Fuji-Bell 204B/204B-2 – Civil utility transport helicopter. Built under licence in Japan by Fuji Heavy Industries alongside military HU-1B and HU-1H for the Japan Ground Self Defense Force. Bell 205 Bell Helicopter's company designation of the UH-1H. Bell 205A – Civil or military utility transport helicopter. Powered by one T53-11A, max weight 8,500 pounds, max passenger, 14. Agusta-Bell 205 – Civil or military utility transport helicopter. Built under licence in Italy by Agusta. – Civil or military utility transport helicopter version, initial version based on the UH-1H. Powered by one T53-13A, max weight 9,500 pounds (10,500 for external loads), max passengers, 14. Agusta-Bell 205A-1