MD Helicopters traces its roots back more than 50 years to when Hughes Tool Company, Aircraft Division first started to develop “light helicopters” in 1955. After years of successfully manufacturing such models as the Hughes 269, 300, 500 and 530F for civil use and TH-55 Osage, OH-6 Cayuse and highly successful AH 64-Apache, Hughes sold its helicopter business to McDonnell Douglas in 1984. For the most part, McDonnell Douglas stayed true to the original Hughes designs and nomenclatures.
In 1997, McDonnell Douglas merged with Boeing to become the Boeing Company.
In 1999, Boeing sold the former MD commercial helicopter lines to MD Helicopter Holdings, Inc., an indirect subsidiary of the Dutch company, RDM Holding Inc. Included in the sale were the MD 500E and MD 530F single-engine helicopters, with conventional tail rotors; the MD 520N and MD 600N single-engine helicopters, with the Boeing-exclusive NOTAR® no tail rotor system for anti-torque and directional control; and the MD Explorer series of twin-engine, eight-place helicopters.
Boeing maintained the AH-64 line of helicopters, and rights to the NOTAR system.
MD Helicopters Holdings, Inc., was acquired in July, 2005, by Patriarch Partners, LLC, an investment fund. The company was recapitalized as an independent company, MD Helicopters, Inc.
MD Helicopters is based in Mesa, AZ, and the current product line includes the MD 500E, MD 530F, MD 520N, MD 600N and the MD Explorer.
In 1960, the U.S. Army issued a specification for a four- or five-seat light single-engine turbine observation helicopter. The helicopter was to use the new Allison (now Rolls-Royce) 250 engine. Hughes (now MD Helicopters) won the competition with the Model 369 and received an order from the Army for 1,000 aircraft. An integral part of the development process was that commercial certification was obtained in tandem with meeting the U.S. Army requirements. The first military deliveries occurred about 1966 and full-scale production of the commercial model, called the Hughes 500, started in 1968. The first improvement of the Model 500, the 500C, was aimed at improving its hot and high performance. The next improvement, in 1976, involved a significant redesign of the main rotor, tail rotor and transmission. With the addition of a higher rated engine this resulted in a substantial increase in maximum takeoff gross weight and a significant increase in performance. This model is referred to as the 500D.
In 1984, McDonnell Douglas acquired Hughes helicopters and redesignated the Model 500 as the MD 500. When Boeing acquired McDonnell Douglas, it spun off the commercial helicopter group to MD Helicopters, Inc. This organization retained the MD 500 designation.
The MD 500D is a light single-engine turbine helicopter. It uses a five-bladed, fully articulated rotor with metal blades and the Rolls-Royce 250-C20B engine. A four-bladed tail rotor with metal blades provides directional control. And starting with the 500D, a horizontal T-tail assists with pitch control. The fuselage has conventional aluminum construction. The cabin has three seats in front and two seats in the rear. The engine and transmission are mounted on a diagonal behind and below the main rotor head. This yields a very narrow “doghouse” on top of the cabin and makes for excellent maintenance accessibility. It also results in a characteristic bulge that separates the left and right rear seats. A skid landing gear is used for the sake of simplicity.
Development of the 500D was launched in 1971, the first flight took place in 1974 and certification was obtained in 1976. Deliveries started the same year and continued until 1982, when it was superseded by the MD 500E. During this time, almost 1,200 500Ds were delivered.