Last update: 12-01-2010
MD-630 / MD-600
McDonnell Douglas Helicopter Systems announced in 8 November 1994 the streched version of the MD-520N. The project was called MD-630N and developed in total secrecy. Till Heli Expo 1995 in Las Vegas, Nevada, the world press did not see the helicopter. The prototype, a modified MD-520F, flew for the first time at 22 November 1994. The second prototype, a modified MD-520N s/n LN-074, had it 's maiden flight at 6 November 1995. The project was renamed to MD-600N. The third prototype, N600RN s/n RN-001, with the selected engine and rotor head for the MD-600 project flew on 15 December 1995 for the first time. This prototype wend lost during certification tests involving rapid cyclic control reversals. Tail boom separated and pilot landed in power off autorotation, but the engine exhaust ignited the surrounding dru scrub and aircraft was burned. Pilot was not injured. After investigation the tailboom/rotor clearance was increased. The second production aircraft became the fourth prototype, N630N s/n RN-002. During the testflights 3 accidents are recorded. All the accidents happend during height velocity curves at a maximum gross weight and zero airspeed. The first time, on 4 November 1996. the rotorblades hit the tailboom during the slide after an autorotation landing. After that,on 21 November 1996, the aircraft landed hard exceeding the maximum load for the landing gear system. The thirth accident, on 18 January 1997, the helicopter touched down hard, the skids collapsed, and the tailboom was severed by the main rotor blades. Aircraft was lost after this landing. After investigation rotor minimum RPM was raised and the anti-torque thrusters exit was moved to the top of the tailboom, increasing fuselage nose-up attitude to add clearance between blades and boom. Also strengthen the gear strut and skid.
The production started at 28 March 1995 but the deliveries originally scheduled for 18 December 1996, devided to 15 May 1997 and delayed to 6 June 1997. The certificate was handed over on 15 May 1997 and certified on the cerficate of the MD-520N.In July 1998, Boeing, McDonnell Douglas was merged with Boeing then, completed a year-long envelope expansion programme for the MD 600N leading to FAA approval for operation at a density altitude of 2,135m at a take-off weight of 1,746kg and at a density altitude of 1,220m at a take-off weight of 1,860kg. This was for a costumer of McDonnell Douglas which made plassure flights with passengers. Other upgrades will allow operators to fly the MD 600N with doors off at speeds to 212 km/h, operate at temperatures up to 52 °C, and lift up to 970 kg on its external hook. The aircraft has also been certified to land on slopes of up to 10 ° .
Yaw-stability augmentation system (Y-SAS) started with the development during 2000, aimed at reducing pilot workload during extended flights and in turbulent conditions. Y-SAS certification was earned in July 2001, is field-installable and sold as an option for the MD-600N.
Beginning with 2007 aircraft deliveries, all MDHI products will include wire strikes, cockpit voice and video recorders, health and usage monitoring systems (HUMS), terrain awareness warning system (TAWS). Additionally, a Fly Safety Training package will be added to MDHI's Training Program. In addition, we will make available a ‘safety kit’ and support to retrofit all existing aircraft