Laughlin, NV, USA
N451DL
McDonnell Douglas 600N
The McDonnell Douglas 600N helicopter sustained substantial damage to the tail boom and rotor blades during startup. The helicopter was parked on a formal helipad atop a 26-story building. After the pilot performed a routine preflight, he and the passengers boarded the helicopter for a local area flight. On engine startup, after about two revolutions of the rotor blades, three of the five blades contacted the tail boom. The pilot stated that the helicopter was pointed south, with the wind out of the north about 20 knots. The wind condition was not unusual for the area and location. The routine for a downwind liftoff was to perform a pedal turn into the wind for departure. The pilot stated that there is nothing in the Rotorcraft Flight Manual nor in the formal factory training for startup in windy conditions. Investigators reviewed the information in the Rotorcraft Flight Manual and found no limitations or restrictions concerning starting engines in strong wind conditions. According to FAA Aircraft Certification information, the helicopter complies with the minimum requirements for main rotor blade separation from the tailboom. According to an engineer in the Aircraft Certification Office responsible for the Type Certificate, the helicopter has a history of and is susceptible to main rotor strikes on the tailboom, if the main rotor rpm drops while the helicopter is either skidding to a halt, or is stationary in a strong wind.
On October 24, 2001, about 1400 Pacific daylight time, a McDonnell Douglas 600N helicopter, N451DL, operated by the pilot, sustained substantial damage to the tail boom and rotor blades during startup at Laughlin, Nevada. Neither the pilot nor the five passengers were injured. Visual meteorological conditions prevailed for the personal flight operating under 14 CFR Part 91, and no flight plan had been filed. The helicopter was parked on a formal helipad atop a 26-story building. After the pilot performed a routine preflight, he and the passengers boarded the helicopter for a local area flight. On engine startup, after about two revolutions of the rotor blades, three of the five blades contacted the tail boom. The pilot stated that the helicopter was pointed south with the wind out of the north about 20 knots. The wind condition was not unusual for the area and location. The routine for a downwind liftoff was to perform a pedal turn into the wind for departure. The pilot stated that there is nothing in the Rotorcraft Flight Manual nor in the formal factory training for startup in windy conditions. A review of the Rotorcraft Flight Manual for the 600N by Safety Board investigators found no reference to startup restrictions in windy conditions. According to a Federal Aviation Administration Rotorcraft Certification Engineer, "The helicopter complies with the minimum requirements for main rotor blade separation from the tailboom; however, the helicopter is susceptible, and has a history of tailboom damage if the main rotor rpm drops while the helicopter is either skidding to a halt, or is stationary in a strong wind."
the manufacturer's failure to provide warning information and ground training about the possibilities of boom strikes by the rotor blades in windy conditions and low rotor rpm situations.
Source: NTSB Aviation Accident Database
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