McDonnell Douglas Helicopter Systems (MDHS) is revising the entire certification plan for the MD600N, following a series of mishaps during high-velocity testing which have already caused more than a two-month delay in receiving approval. Certification is not now expected until late March at the earliest.
Another MD600N has restarted test work where the programme left off after the crash-landing of a test aircraft at Flagstaff, Arizona, on 18 January. Although around 90% of the flight-test programme had been completed at the time of the last incident, the testing is now proceeding at a more cautious rate. "We're gradually building up weight, bit by bit," says Explorer general manager, Jerry Ryan. "We are doing a slower weight build-up, reviewing the data and then taking another look," he adds.
The test team is also conducting a total review of the scope of the certification plan, which is expected to grow to include a wider variety of options. "It will include certifying things like floats, external hoists and searchlights. Much more will be certified before delivery, so the emphasis is to make the certification more global in perspective," says Ryan. The review was prompted by the MD600N incidents and the eight-month delay in instrument certification of the MD900 Explorer. "We want to be able to deliver things when we say we will," he adds.
Senior vice-president Dean Borgman says: "We're holding the certification of the MD600N, and we're taking that action on our own, even though we've satisfactorily completed most of the certification testing under FAR37 [Federal Aviation Regulation 37]. It didn't happen in December, because of our own actions. We made the decision to do more certification work on the aircraft because we were not satisfied that it was ready to meet the full range of operations our customers expect. We are reviewing it subsystem by subsystem to make sure we get all the bugs out of it."
The first aircraft was due to be handed over to Grand Canyon tour operator AirStar at a ceremony in the middle of December. This was delayed by the first Flagstaff incident in November and a planned delivery ceremony at Heli-Expo on 2 February was then prevented by a repeat incident on 17 January.
MDHS delivered 67 helicopters in 1996, including the last of 937 AH-64A Apaches. Of the total delivered, some 38 were AH-64As, 15 MD900 Explorers and 14 MD500s.
Source: Flight International
