Schweizer 269C N290R accident near Forest Grove, Oregon

Probable cause

A partial loss of engine power during cruise flight for reasons that could not be determined because postaccident examination of the airframe and engine did not reveal any anomalies that would have precluded normal operation.

NTSB analysis

The commercial pilot reported that, during low-altitude cruise while conducting a positioning flight and with the helicopter about 40 knots and 55 ft above ground level, the engine lost power, and the helicopter began to lose altitude. During the subsequent autorotation, the helicopter struck some wires near the ground, which resulted in a dynamic rollover. The helicopter came to rest on its left side nearly inverted.

A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. Further, the engine was test run at a low-power setting with no anomalies noted.

Text from the NTSB. Open the NTSB docket for WPR15LA261 for the full record.