Accident Summary
A helicopter lost partial power during a climb out from maneuvering in a canyon. The aircraft subsequently rolled over after the pilot landed right skid first on a sloped and uneven embankment. The pilot had received a weather briefing prior to takeoff and noted no abnormal weather conditions.
Flight Details
The pilot reported turning on the carburetor heat at the start of the flight and leaving it on for the entire duration, approximately 45 minutes. Before entering the canyon where the accident occurred, the pilot conducted in-ground-effect (IGE) and out-of-ground-effect (OGE) hovers to ensure adequate power was available. The pilot then maneuvered through the canyon at about 150 feet above ground level and initiated a climb.
Engine Power Loss
According to the pilot, he had just checked the engine gauges, including the carburetor air temperature gauge, and all were within normal ranges when the engine began to sputter and lose power. The pilot entered an autorotation and confirmed that the carburetor heat control was still in the ON position and the carburetor temperature gauge remained in the green during the descent.
Landing and Rollover
The pilot reported a successful touchdown on the right skid on a slope. The engine was still running but produced insufficient power to keep the helicopter level. The helicopter subsequently rolled over onto its left side.
Post-Accident Inspection
An airframe inspection and engine test run were conducted. No anomalies were found with either the airframe or engine that would have precluded normal operation.
Weather Conditions
Weather reported for the accident area included a temperature of 60 degrees Fahrenheit and a dew point of 52 degrees Fahrenheit. According to the carburetor icing probability chart, these conditions were conducive to moderate icing at cruise power or serious icing at glide power.