McDONNELL Douglas Helicopter Systems (MDHS) will deliver its first MD 600N in early June, to Grand Canyon tour operator AirStar Helicopters, following delayed US certification.
The company has seven aircraft ready for hand over, and hopes to deliver up to 30 of the tailrotor-less MD 600Ns this year.
Follow-on certification efforts are already under way, with deliveries planned this year to customers in Argentina, Australia, Belgium, Brazil, Finland, France, Germany, Hong Kong, Japan, Mexico, Norway, South Africa, Switzerland, the UK and Venezuela, as well as the USA. MDHS has orders for more than 40 aircraft.
Certification was delayed by design changes resulting from a series of flight-test incidents. To prevent rotor-blade strikes on the tailboom, rotor minimum RPM was raised and the anti-torque thruster exit was moved to the top of the tailboom, increasing fuselage nose-up attitude to add clearance between blades and boom. Control runs for the horizontal stabiliser were moved to the bottom of the boom to prevent them being severed by a bladestrike.
The 600N is a stretched derivative of MDHS' MD 520N light single-turbine helicopter. The aircraft has a six-blade rotor, eight-place cabin and uprated Allison 250-C47M turboshaft with full-authority digital engine-control. Preliminary results from noise testing indicate that the 600N is quieter than both the 520N and the Explorer light twin, MDHS says. All three helicopters have the NOTAR anti-torque system.
MDHS has delivered 80 520Ns and 30 Explorers, and says that operators have accumulated more than 100,000h of flying without any NOTAR-related incidents.
Source: Flight International
