Robinson Helicopter Company R44 II N4246Z accident near Pahrump, Nevada

Probable cause

A total loss of engine power during a practice autorotation 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 a practice autorotation, a total loss of engine power occurred about 3,500 ft above ground level. The pilot made several unsuccessful attempts to restart the engine, and he subsequently performed an autorotation emergency landing. During the landing, the helicopter slid forward about 20 ft, the skids dug into the dry lakebed, and the helicopter then nosed over. Subsequently, the main rotor blades impacted the ground, and the helicopter came to rest on its side.

A postaccident examination of the airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The engine was test run at various power settings with no anomalies noted.

Text from the NTSB. Open the NTSB docket for WPR14LA353 for the full record.