BK117 fuselage for Graupner Bell 47G

The BK 117 was a joint development between MBB and Kawasaki based on an agreement made on 25 February 1977. The agreement would replace two separate developments by both companies; the Bo 107 by MBB and the KH-7 from Kawasaki. Costs were shared equally with MBB developing the rotors, tailboom, flight controls and hydraulic system and Kawasaki developing the landing gear, airframe, main transmission and other minor components.

Each company was to build two prototypes, to be completed by 1979; one for static ground testing and the other for flight testing. Delays at Kawasaki caused only one of the prototypes to be completed on time. However, the Kawasaki prototype first flew only several weeks later than the MBB prototype.

A single BK 117-A3 was leased by the Canadian Forces Air Command for a test program and designated as the CH-143. When the program was over, the aircraft was returned to MBB Canada.

Originally known as the BK 117-C2, the EC 145 combines the original BK 117 design with a much larger cabin, and modern features from the EC 135.