Accident Overview
During an aerial application maneuver, a helicopter began losing engine power. The pilot attempted to land in the field where the helicopter was operating. The helicopter impacted terrain approximately 80 yards from an access road at the north edge of the field. The helicopter sustained substantial damage, but the pilot was uninjured.
Post-Accident Examination
An examination of the helicopter revealed that the carburetor heat control spring, which keeps the carburetor closed, was broken. The support rod for the spring had worn into the housing. As a result, the heat valve could only be opened about one-third of its full range. The corresponding cockpit control remained in the closed position. The fracture surface of the spring was consistent with fatigue. The spring had accumulated a total time in service of 832 hours.
Pilot Background and Reporting
The pilot was a certificated aircraft mechanic who also performed maintenance on the helicopter. A National Transportation Safety Board Pilot/Operator Aircraft Accident/Incident Report was not received from the pilot.