NTSB Identification: WPR09LA350
14 CFR Part 91: General Aviation
Accident occurred Wednesday, July 15, 2009 in Sequim, WA
Probable Cause Approval Date: 07/22/2010
Aircraft: BIELAWA ROTORWAY E, registration: N3213K
Injuries: 2 Minor.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

During a stationary low hover of the recently built experimental helicopter, it suddenly and without warning rotated rapidly in a counter-clockwise direction around its longitudinal axis, and immediately impacted the ground. The investigation determined that one of the main rotor blades had failed (disbonded), leading to an immediate loss of control in flight. The composite blade, which was designed specifically for use on one manufacturer's experimental helicopter, was being used on another manufacturer's experimental helicopter, as allowed by its experimental designation. Due to the lack of sufficient engineering, manufacturing, and testing data, the precise initiating factor of the disbonding event could not be determined.

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

The failure (disbonding) of a composite main rotor blade for undetermined reasons, leading to an immediate loss of control in flight during hover.

Full narrative available

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