Design of the AS365 family of medium twin-engine helicopters started in the early 1970s, and used the AS360C medium single-engine helicopter as a point of departure. The design was one of the first to be executed by the newly formed helicopter division of French aircraft manufacturer, Aerospatiale. Aerospatiale was formed in the early 1970s by combining most of the French government-owned aerospace companies, including Sud Aviation, which had been responsible for helicopter design and production. In the 1990s, the helicopter division of Aerospatiale was merged with the German MBB helicopter company to form Eurocopter. Today, Eurocopter is a division of EADS, a multinational European aerospace giant.
The AS365 was a new design that incorporated composite rotor blades, a composite rotor head and a Fenestron-shrouded, 11-blade tail rotor using composites. The first member of the AS365 family (the AS365C) used a fixed, wheeled landing gear in a tail-dragger configuration. This was changed to a conventional retractable landing gear configuration with the AS365N. This model also used composites for a substantial portion of the fuselage. The cabin can accommodate up to 12 passengers in addition to two pilots. Alternatively, the large cabin can accommodate up to four stretchers longitudinally in the cabin.
The AS365 has had some success in the commercial sector. However, it has been most successful with military and paramilitary customers. For example, the U.S. Coast Guard acquired a fleet of more than 90 of these helicopters, using the Lycoming LTS 101 engine, for search and rescue missions. These helicopters, called the HH-65A Dolphin by the Coast Guard (and AS366G1 by Eurocopter), have proven to be very effective. In addition, the Maryland State Police acquired 13 for their statewide EMS service.
The drivetrain for the AS365N3 uses two Turbomeca Arriel 2C engines and a four-bladed composite rotor head and blades. The AS365N3 is approved for single-pilot IFR operations and is also approved for Category A single-engine operations. The AS365N3, differs from its stable mate, the AS365N2, by having more powerful engines and a higher maximum takeoff gross weight.
The AS365N3 was certificated in 1999 and has been in production since that time.