The MD Helicopters MD Explorer is a light twin utility helicopter. Designed in the early 1990s by McDonnell Douglas Helicopter Systems, it is currently produced by MD Helicopters, Inc. There have been two models, the original MD 900, and its successor, the MD 902.
Design and development
The MD Explorer light twin helicopter is the first all new design to incorporate the unique NOTAR system. McDonnell Douglas Helicopters launched the Explorer as the MDX in January 1989. First flight took place on 18 December 1992. Full certification for the initial PW206B powered Explorer (unofficially designated MD 900) version was granted in December 1994.
One of the most advanced helicopters in its market segment, the MD Explorer features Boeing's unique NOTAR anti-torque system, with benefits including increased safety, far lower noise levels and performance and controllability enhancements. Instead of an anti-torque tail rotor, a fan exhaust is directed out slots in the tail boom, using the Coandă effect for yaw control. Boeing retains the design rights to the NOTAR technology despite selling the former McDonnell Douglas civil helicopter line to MD Helicopters in early 1999.
The Explorer also features an advanced bearingless five blade main rotor with composite blades, plus carbonfibre construction tail and fuselage.
Initial Explorers were powered by two Pratt & Whitney Canada PW206As (the Explorer was the first application for the Pratt & Whitney Canada PW200 series), while plans to offer the Turbomeca Arrius as an option were dropped. In September 1997 a range of improvements were introduced, including PW206E turboshafts with higher single engine inoperative ratings, revised engine air inlets, improved NOTAR inlet design and a more powerful stabiliser control system. Benefits include improved range and endurance and an increased max takeoff weight. This enhanced Explorer was unofficially designated the MD 902.
From September 2000 the Explorer has been delivered with the further improved PW207E turboshaft, with improved hot and high and one engine inoperative performance.
In August 2008, 30 MD Explorers operating in the United Kingdom were grounded, on the orders of McDonnell Douglas, following an incident involving a London air ambulance.
Specifications (MD 902)
Published - July 2009
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