The original model was the A109. This was followed very quickly by the A109A. This production version had a higher takeoff gross weight and some other improvements. The 109A was succeeded by the 109A Mark II. This version is essentially the same as the 109A, except for the installation of a higher rated main transmission. In addition, an improved engine was made optional to enhance single-engine performance. Partway through the production run of the Mark II, the width of the cabin was increased by about 5 inches through the installation of bulged doors and restyling of the sides of the fuselage. These models are also referred to as the 109A+ or 109A2. Many, if not all, of the improvements can be installed on earlier versions.
The Agusta 109A is an eight-place helicopter that was designed in response to a need from the marketplace for a 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 on top the other on one side of the cabin. In this configuration, there is also room for two medical attendants. An alternate EMS configuration has radically bulged cabin doors that allows loading one stretcher across the width of the cabin.
The Agusta 109A drivetrain uses two Rolls-Royce 250-C20B engines, a four-bladed, fully articulated rotor and a two-bladed tail rotor. All blades are made of aluminum, as is the fuselage. The drivetrain for the 109A Mark II offers the 250-C20R as an option. The A109A uses a retractable landing gear.
Design of the Agusta 109 was launched in the mid-1960s. The first flight of the Agusta 109 took place in 1971 and certification to the standards of FAR 27 was obtained in 1975. The 109A, the production version, was certificated in 1976 and IFR certification was also obtained. The upgraded 109A Mark II version was introduced in 1982 and production of the Agusta 109A and 109A Mark II concluded in 1991. During this time, a total of approximately 335 were delivered to both commercial and military customers.