NTSB Identification: IAD05LA084.
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Accident occurred Saturday, June 25, 2005 in Cleveland, OH
Probable Cause Approval Date: 04/25/2006
Aircraft: Bell 206B, registration: N1212N
Injuries: 1 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.

The pilot was hovering the helicopter above an airport at 5,000 feet msl, when he heard a loud "bang." Witnesses on the ground also reported hearing the "bang," and a puff of white smoke was also observed. The helicopter yawed in a nose right direction, and pitched nose down. The pilot regained control of the helicopter about 1,500 feet msl, and subsequently performed an autorotation to a runway. The helicopter landed "hard," and the main rotor contacted the tail boom, separating it from the helicopter. Inspections of the helicopter following the accident revealed that the isolation mount had separated from the transmission and that the main drive shaft had separated. Examination of the main drive shaft, and its associated couplings, revealed failures consistent with an excessive angular displacement between the rotational axis of the drive shaft and the couplings. Examination of the helicopter's transmission compartment revealed damage to the structure around the main drive shaft and grease spray consistent with rotation prior to its failure. In addition, small pieces of metal and metallic dust were identified at the very front of the transmission deck.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

A failure of the main drive shaft for undetermined reasons, which resulted in a total loss of engine power. A factor was pilot's improper flare, which resulted in a hard landing.

Full narrative available

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