NTSB Identification: NYC00FA127
14 CFR Part 91: General Aviation
Accident occurred Saturday, May 06, 2000 in CINCINNATI, OH
Probable Cause Approval Date: 05/30/2001
Aircraft: Eurocopter BK-117-A4, registration: N911NC
Injuries: 1 Serious.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
The pilot stated he approached the lighted rooftop helipad from the southwest, at night, with light winds. The helipad and hangar were just ahead of him, and he initiated a right pedal turn to align the helicopter towards the south. He heard a loud bang, and the helicopter rotated uncontrollably, nose right. He lowered the collective, and the helicopter struck the landing area. Examination revealed the tail rotor blade ends were fragmented, and marks on the top corner of the hangar were similar to a tail rotor blade strike. Due to other helicopters parked on the ramp, the only approach was from the southwest. Winds were estimated to be from 220 degrees at 10 knots with gusts to 15 knots. Examination of the hydraulic pump and hydraulic tail rotor actuator found no evidence of failure or malfunction. Personnel reported the windsock would occasionally get caught on its support structure, and not indicate the true nature of the wind. There was no other wind information available to the pilot.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: the pilot's misjudgment of his closure rate, while turning to land on the rooftop helipad, which resulted in a collision with the building. Factors in the accident were the tailwind and the stuck windsock. Full narrative available
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