Amateur-built SAFARI N105KM accident near Middle Valley, Tennessee

Probable cause

A partial loss of engine power for reasons that could not be determined due to the postaccident condition of the airframe and engine.

NTSB analysis

The pilot of the experimental amateur-built helicopter reported that the engine shuddered twice momentarily shortly after takeoff and then lost power. After observing the engine rpm drop from about 2,700 to 1,500, the pilot initiated an autorotation and subsequently landed the helicopter on top of a tree, which began to lower toward a creek. The helicopter came to rest partially submerged in the creek and was partially consumed by a postcrash fire. Postaccident examination of the wreckage did not reveal any preimpact malfunctions or failures that would have precluded normal operation; however, impact and fire damage precluded the ability to functionally check the engine and fuel system. Review of engine monitor data, which was recorded at 5-second intervals, did not reveal any drops in engine rpm or any other anomalies consistent with the pilot's statement.

Text from the NTSB. Open the NTSB docket for ERA12LA226 for the full record.