LAX04LA073 · Robinson R22 Beta

The engine lost partial power during climb out from maneuvering in a canyon and the helicopter rolled over after landing right skid first on a slopped and uneven embankment. Prior to takeoff, the pilot received a weather briefing and noted no abnormal weather conditions. The pilot said he turned on the carburetor heat and left it in that position for the duration of the flight, about 45 minutes. To ensure adequate power was available, the pilot conducted in ground effect (IGE) and out of ground effect (OGE) hovers prior to entering the canyon where the accident occurred. The pilot entered a climb after maneuvering at 150 feet above ground level through the canyon. He reported that he had just checked the engine gauges (including the carburetor air temperature gauge), all of which were in the normal range, when the engine began to sputter and lose power. The pilot said he entered an autorotation and checked that the carburetor heat control was still in the ON position and that the carburetor temperature gauge was in the green during the descent. The pilot said he completed a successful touchdown on the right skid on a slope; the engine was still running, but insufficient power was being produced to keep the helicopter level. The helicopter then rolled over on its left side. An airframe inspection and engine test run were conducted. There were no anomalies with either the airframe or engine that would have precluded normal operation. Reported weather for the accident area showed the temperature as 60 degrees Fahrenheit, and the dew point was 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.

Verbatim NTSB analysis and probable cause from the NTSB dataset