In 1967 the French Air Force was investigating replacement aircraft for the Douglas DC-3 and Beechcraft 18 twin-engine aircraft being used for light transport and pilot navigation training. They solicited proposals from the French industrial community, and specified that any submittals would be powered by Astazou turboprops of 870 hp.
In response to this request, Dassault designed and constructed a single prototype, the M.D.320. It was later named Hirondelle (Swallow). Its design and construction were fairly rapid, because it extensively used the Dassault Falcon 20 (which first flew in 1963) as a basis. The fuselage length and volume were identical to the Falcon 20, and its wing and control surfaces were adaptations of the 20.
The Hirondelle was an all-metal low-wing monoplane with swept vertical tail. The wing and tailplane were slightly swept. It used a retractable tricycle undercarriage, with the main gear retracting into the engine nacelle.
The Hirondelle had a circular cross-section fuselage with accommodation for a crew of two and room for a maximum of 14 passengers. There were 5 round windows on each side of the pressurized fuselage.
The prototype (French civil registration F-WPXB) was powered by two Turbomeca Astazou XIVD turboprop engines mounted in wing nacelles, driving three-blade fully feathering propellers. Production aircraft would have had Astazou XVI engines.
The Hirondelle wings contained integral fuel cells. The airframe was designed using fail-safe principles.
The prototype first flew on 11 September 1968, at Bordeaux-Mérignac. It was piloted by Hervé Leprince and Jean Foureau.
In 1968 the French Air Force procurement office reversed its previous position and announced that it was seeking jet-powered aircraft for the DC-3/Beechcraft 18 replacement program. Despite this, the Marine Nationale displayed interest in the aircraft for use as a carrier based airborne early warning, carrier onboard delivery, and anti-submarine warfare aircraft.