Robinson R44 N510JM accident near Pahrump, Nevada

Probable cause

The loss of the engine to transmission drive train continuity while on approach for undetermined reasons. Contributing to the accident were lack of suitable terrain for a run-on landing, and cars on the race track.

NTSB analysis

During an approach to landing near a race track, the pilot noticed that the clutch warning light became illuminated for about 7 seconds along with fluctuations in main rotor rpm for about 4 seconds. The pilot shortened his approach, and subsequently heard the low rotor rpm warning horn. He saw the low rotor rpm warning light, and immediately initiated an autorotation to the racetrack. Due to oncoming high speed vehicles on the track, the pilot extended his approach slightly beyond the track, and made a run-on landing to a level dirt area. The helicopter rolled over, and came to rest on its left side, resulting in substantial damage to the fuselage and the separation of the tail boom. Examination of the airframe, engine, clutch drive train components, and the associated warning systems revealed no anomalies that would have precluded normal operation.

Text from the NTSB. Open the NTSB docket for SEA08LA104 for the full record.