Robinson Helicopter R22 BETA N104MH accident near Isabel, South Dakota

Probable cause

The partial loss of engine power due to carburetor ice.

NTSB analysis

While maneuvering at low altitude during a coyote hunting operation, the helicopter experienced a partial loss of engine power. The helicopter descended, impacted trees and terrain, and rolled on its right side. There was a minor fuel leak but no postimpact fire. A postaccident examination of the helicopter did not reveal any evidence of preimpact mechanical malfunction or failures that would have precluded normal operation. Based on the temperature and dew point about the time of the accident, the conditions were conducive to serious carburetor icing at any power setting. The pilot reported that he was unsure if he had used carburetor heat for the accident flight. Available evidence suggests that the engine partially lost power in the absence of carburetor heat while operating in conditions conducive to carburetor icing.

Text from the NTSB. Open the NTSB docket for CEN12LA230 for the full record.