The Bell 412 is a utility helicopter of the Huey family manufactured by Bell Helicopter. It is a development of the Bell 212, with the major difference being the composite four-blade main rotor. Design and development Development began in the late 1970s with two Bell 212s being converted into 412 prototypes. An advanced four-blade main rotor with a smaller diameter replaced the 212's two-blade rotor. A Bell 412 prototype first flew in August 1979. The initial model was certified in January 1981 with deliveries commencing in the same month. The 412 model was followed by the 412SP (Special Performance) version featuring larger fuel capacity, higher takeoff weight and optional seating arrangements. In 1991, the 412HP (High Performance) variant with improved transmission replaced the SP version in production. The current production version, 412EP (Enhanced Performance), is equipped with a dual digital automatic flight control system. In 2013 Bell introduced the 412EPI which includes an electronic (digital) engine control for a PT6T-9 engine upgrade, and a glass cockpit display system similar to the Bell model 429. Also featured is a Garmin touchscreen navigation system, and the BLR Strake and Fast Fin upgrades for improved hover performance. Over 700 Model 412s (including 260 by AgustaWestland) have been built. Variants Bell 412 Standard Model with P&WC PT6T-3B Special Performance version with P&WC PT6T-3BF engines Bell 412HP High performance version with P&WC PT6T-3BG or -3D engines Bell 412CF (CH-146 Griffon) 100 custom-built utility transport helicopters for the Canadian Forces, based on 412EP and designated by Bell as 412CF Enhanced performance version with P&WC PT6T-3DF engines Bell 412EPIGlass cockpit version with P&WC PT6T-9 electronic controlled engines Bell Griffin HT1 Advanced training helicopter based on the Bell 412EP, operated by the Royal Air Force (RAF) since 1997 as an advanced flying trainer. Operated by the Defence Helicopter Flying School at RAF Shawbury and the Search and Rescue Training Unit at RAF Valley. Bell Griffin HAR2 Search and Rescue helicopter based on the Bell 412EP, operated by No. 84 Squadron RAF since 2003 at RAF Akrotiri in Cyprus. Agusta-Bell AB 412Civil utility transport version, built under license in Italy by Agusta. Agusta-Bell AB 412EP Italian-built version of the Bell 412EP. Agusta-Bell AB 412 Grifone Military utility transport version, built under licence in Italy by Agusta. Agusta-Bell AB 412 CRESO Italian-built version, fitted with a ground surveillance radar. NBell 412 Indonesian IPTN's licensed product of Bell 412 Subaru-Bell UH-2