Diamond IA A054SAThe History behind this Exclusive Jet
In 1977 Mitsubishi embarked on the design of a new business jet known as the MU-300. This aircraft, subsequently called the ‘Diamond’, was a conventional low wing design with a T-tail and two P&W JT15D turbofans mounted on the rear fuselage. For a small jet, it had a large cabin for eight passengers, an aft lavatory and baggage. Initial testing was done in Japan and then the two prototypes were transferred to Mitsubishi’s facility in San Angelo, TX to complete its FAA testing for FAR Part 25.
It received its Type Certificate on 6 November 1981. Thereafter, production Diamond Is were assembled in San Angelo from components produced in Nagoya, Japan. By late 1985 Mitsubishi had delivered 100 Diamonds from its San Angelo facility. At that time Mitsubishi sold the MU-300 package to Beechcraft where it became known as the Beechjet 400.
Standard accommodation was provided for a crew of two and seven passengers. At the end of the development program the prototypes were dismantled and shipped to the USA, where they were reassembled by the company’s US subsidiary Mitsubishi Aircraft International Inc. Redesignated the Diamond I, the two aircraft were used in the US certification programme, which was granted on 6 November 1981. Initial customer deliveries began in July 1982 and 62 were built.
Comfort & Size
An improved version, the Diamond IA, fitted with uprated JT15D-4D engines giving overall performance increases, an EFIS cockpit and with maximum take-off weight increased to 7361kg, was announced in 1983 and the first of 27 built, distinguished by the extra port side window, was delivered in 1984.
The Diamond I was made mostly of aircraft aluminum alloy. Its wings had a sweepback of 20 degrees at quarter chord and an incidence of three degrees. Each wing had trailing-edge flaps running almost the full span, with double slotted flaps inboard and single slotted flaps outboard, with a small aileron near each wingtip. There were spoilers above the wing to aid in roll control, as well as to act as airbrakes and lift dumpers. There was a small fence about a third of the way outboard on the wing. De-icing was by engine bleed air.
The tailfin had a long leading fillet, with a small yaw damper surface above the rudder. The tailplane featured elevators, and had variable incidence to handle flight trim. There was a ventral fin under the tail, and a small strake along each side of the tailfin. All landing gear assemblies had single wheels, the main gear hinging in the wings to retract towards the fuselage, the steerable nose gear retracting forward.