NTSB Identification: DEN07LA132.
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Accident occurred Wednesday, August 01, 2007 in Broomfield, CO
Probable Cause Approval Date: 09/27/2007
Aircraft: Bell 206B, registration: N568TD
Injuries: 2 Minor,2 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.

According to the pilot, this was his sixth sightseeing flight of the day. He had just landed and three passengers disembarked. Three other passengers boarded the helicopter. As the pilot brought the throttle to full rpm and increased torque, the helicopter turned left about 15 degrees. Approximately 3 inches of opposite pedal was used to bring the helicopter back to its original heading. The pilot continued to increase torque and as the skids started to come off the ground, the nose pitched up rapidly and the helicopter rolled to the right. The left skid was about 3 inches off the ground during the yaw. The right skid never left the ground. Full forward and left cyclic had no effect. The pilot then lowered collective and tried to roll off the throttle. The helicopter rolled right until the main rotor blades contacted the ground. A piece of main rotor blade struck a nearby hangar. The pilot reported no control anomalies and a subsequent examination revealed no discrepancies. FAA's "Rotorcraft Flying Handbook" (FAA-H-8083-21) defines "dynamic rollover" as "the tendency of a helicopter to continue rolling when the critical angle is exceeded, if one gear is on the ground, and the helicopter is pivoting around that point."

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

The pilot's failure to maintain control of the helicopter, resulting in an inadvertent dynamic rollover.

Full narrative available

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