Robinson Helicopter Company R22 Beta N137DF accident near New Braunfels, Texas

Probable cause

The pilot's improper flare during an autorotation, which resulted in a hard landing, and a partial loss of engine power for reasons that could not be determined because the examination of the engine did not reveal any anomalies that would have precluded normal operation.

NTSB analysis

The pilot reported that, after completing a low pass and while in a climbing right turn, he heard the engine "sputter" and then noted that both the engine and main rotor speeds had dropped. The pilot stated that he entered an autorotation to a field because there was not enough altitude to fully recover from the partial loss of engine power. The helicopter bounced during the initial collision with terrain. A postaccident examination of the helicopter and an operational test run of the engine did not reveal any preaccident mechanical malfunctions or failures that would have prevented normal operation.

Text from the NTSB. Open the NTSB docket for CEN13LA325 for the full record.