The original model, in this series, was the A109. The first production version was the A109A, which was succeeded by the 109A Mark II and the A109C. Each model incorporated various improvements, including a higher rated main transmission, an improved engine, increased cabin width and a higher takeoff gross weight. The original A109C had only average OEI and hot and high performance. This was addressed with the introduction of the A109K2. This helicopter uses higher powered engines, an upgraded transmission and a significant redesign of the fuselage. This redesign involved increasing the length and width of the cabin, increasing the capacity of the fuel tank and the use of a fixed, wheeled gear instead of a retractable gear.
The Agusta 109K2 is an eight-place light twin-engine turbine helicopter. The cabin has two compartments and the pilot compartment has two seats. The passenger cabin has five or six seats in two facing rows. Alternatively, two litters can be loaded through the side doors and placed one above the other on one side of the cabin. In this configuration, there is also room for two medical attendants.
The Agusta 109K2 drivetrain uses two Turbomeca Arriel 1K1 engines, a four-bladed, fully articulated rotor and a two-bladed tail rotor. The main rotor blades are made of composites. The tail rotor blades are made of aluminum, as is the fuselage.
The design of the original Agusta 109 was launched in the mid-1960s. Development of the A109K2 was started in 1989. The first flight of the Agusta 109K2 took place in 1991. Certification to the standards of FAR 27 with IFR approval was obtained in 1993 and first deliveries started the same year.