NTSB Identification: IAD97LA070.
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Accident occurred Wednesday, April 30, 1997 in KANE, PA
Probable Cause Approval Date: 09/28/1999
Aircraft: Mbb BK-117-A1, registration: N122LF
Injuries: 4 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
After a 30 minute flight to his destination, the pilot found the hospital helipad, which was about a 200 square foot area, with 40 foot high wires on the north side, and 35 to 50 feet high trees surrounding the rest of the area. A windsock indicated about 3 to 5 knots winds from the west/southwest. During the approach from the southwest, the pilot descended vertically to the helipad. The pilot attempted to stop the rate of descent with the airspeed below 10 knots. The helicopter shuttered with the application of additional power. The helicopter yawed right, and 'the additional collective pitch seemed to have no effect on slowing the rate of descent, the rate of descent seemed to increase at this point.' The pilot determined that he did not have sufficient space to fly out of the area and at impact, all remaining collective pitch had been applied. No master caution or annunciator panel lights were noticed, nor was any audio tones heard. A helicopter aerodynamics manual described conditions conducive to settling with power, which included a vertical or near vertical descent of at least 300 feet per minute, engine power between 20 and 100 percent, during downwind steep approaches.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's decision to perform a low airspeed vertical descent with a tailwind, which resulted in settling with power. Full narrative available
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