Accident Overview
A helicopter performing aerial application operations experienced a loss of engine power while executing an ag turn. The pilot reported that carburetor ice was suspected throughout the day, and carburetor heat was applied intermittently. Following the power loss, the helicopter descended into trees and brush.
Investigation Findings
On-scene investigation revealed no indications of mechanical difficulty or malfunction. Fuel was present on board the helicopter, and no evidence of contamination was found in the fuel system. A post-accident engine run was accomplished with no indication of power loss.
Pilot Statement
The pilot stated, "Carburetor ice was suspected throughout the day. Carburetor heat was applied intermittently during the day." The report did not specify the exact time of day, weather conditions, or whether the pilot had experienced any prior power fluctuations.
No Mechanical Failure Found
Despite the reported loss of power, detailed examination of the helicopter and its systems found no anomalies. The engine ran normally during post-accident testing, suggesting that the power loss may have been temporary or related to environmental factors rather than a mechanical defect.
Context
The accident occurred during aerial application operations, a type of flight that often involves low-altitude maneuvering and rapid turns. The ag turn mentioned by the pilot is a standard maneuver in such operations, but the sudden loss of power during this critical phase led to the descent into the treeline.