Mcdonnell Douglas 500D N61PJ accident near Colusa, California

Probable cause

A total loss of engine power while maneuvering at low altitude for reasons that could not be determined because postaccident examinations did not reveal any anomalies that would have precluded normal operation. Contributing to the accident severity was the operation of the helicopter within a portion of the height-velocity regime unfavorable for autorotation.

NTSB analysis

The helicopter was climbing and translating away from a power and communications line tower when the engine experienced a total loss of power. At that time, the helicopter was about 175 feet above ground level and had little forward airspeed, which placed it in the portion of the height-velocity regime unfavorable for autorotation. The helicopter began to descend rapidly, the pilot began an autorotation, and the helicopter subsequently landed hard in a field.

During postaccident examination, manufacturer-specified vacuum leak checks could not determine the preimpact integrity of the fuel system due to impact damage and some initially undetected problems with the vacuum leak check equipment. About 30 gallons of fuel was found in the fuel tank, and it was free of water and other visible contaminants. Further, fuel from the fuel truck that supplied the helicopter was subsequently used in other aircraft without any problems. Detailed examinations of the airframe and engine did not reveal any mechanical deficiencies or failures that would have precluded normal operation.

Text from the NTSB. Open the NTSB docket for WPR12LA022 for the full record.