In the 1950s, Bell Helicopter developed a turbine-engine powered utility tactical transport helicopter for the U.S. Army. This single-engine helicopter, known as the UH-1B or “Huey,” proved to be very popular with the U.S. Army and was quickly stretched to give a bigger cabin. This stretched version became known as the UH-1D in the Army and as the Bell 205 in the civilian world. In the late 1960s, a twin-engine version of the Bell 205 was developed for the U.S. and Canadian armed forces. This model became the Bell 212 in the commercial world. In the late 1970s, in response to customer demand for a smoother ride and higher speed, Bell developed a four-bladed version of the Bell 212 with higher gross weight, an upgraded transmission and more fuel and called it the Bell 412. Over the years, several improvements were made to this helicopter. The first two models to incorporate a number of system improvements were called the Bell 412 SP and the 412HP. Next, upgraded engines, transmissions and further system changes were incorporated into the Bell 412 EP. The Bell 412EPi continues the lineage with increased engine power and with an integrated glass flight deck.
The Bell 412 EPi is a medium twin-engine turbine helicopter. It has a four-bladed composite rotor. The engines used for this helicopter are the Pratt & Whitney Canada PT6-9 Twin-Pac. The Twin-Pac uses a front-mounted combining gearbox also used on earlier models of the Bell 212 and the Bell 205. A two-bladed tail rotor provides directional control. The fuselage is made of conventional aluminum alloys and is mounted on a fixed skid gear. An optional wheeled landing gear is available. The cabin is the same as that of the Bell 205 and Bell 212 and features two pilot seats up front. Behind the pilot seats is the passenger or cargo cabin. It has a flat floor and two large sliding doors provide ready access to every part of the cabin. When used for passenger transport, it can seat up to 13. When used for cargo, it can carry about 5,000 pounds internally or externally. Single-pilot IFR certification for the Bell 412 was obtained in 1981. Category A certification was also obtained. The Bell 412 has been in production since 1981.