Williams Helicopter Corp UH 1H N260TA accident near Waitsburg, Washington

Probable cause

An extreme vibration immediately after entering forward flight for reasons that could not be determined because postaccident examination of the helicopter did not reveal any anomalies that would have precluded normal operation. Contributing to the accident was the pilot’s inability to maintain helicopter control during the landing.

NTSB analysis

The commercial pilot was conducting an agricultural cherry drying flight in the helicopter. Surveillance video showed the helicopter lift off the ground into a momentary low hover, climb and move forward and upward, and then immediately descend while rolling toward its right side until it impacted the ground. The pilot stated that the initial takeoff into the hover felt normal and that he then increased the altitude to get out of a dust cloud generated by the helicopter. As he transitioned the helicopter to forward flight, it experienced a "violent" one-to-one vibration that continued to increase as the helicopter continued forward. The pilot aborted the takeoff and subsequently lost control of the helicopter while attempting to land.

Postaccident wreckage examination did not reveal any anomalies that would have precluded normal operation.

Text from the NTSB. Open the NTSB docket for WPR14LA206 for the full record.