Amateur-built LANCAIR 320 N320BB accident near Temple Bar, Arizona

Probable cause

The pilot did not use carburetor heat in cruise flight while operating in an area conducive to carburetor icing, which resulted in a loss of engine power.

NTSB analysis

According to the pilot, the airplane was in cruise flight at 5,500 feet mean sea level (msl) when he observed haze ahead, and he decided to descend to 3,500 feet msl. The pilot reported that, at 4,000 feet msl, the engine began to lose power. The pilot stated that he cycled the throttle and then the propeller, but the engine power was not restored. The pilot then turned on the fuel boost pump with no change in power noted. The pilot said that he did not apply carburetor heat. The pilot said that, about 300 to 400 feet above ground level, the engine "finally reached what felt like near idle." During the forced landing, the airplane collided with an embankment.

The regional weather conditions at the time of the accident were such that the route of flight was directly into a cold front with increasing moisture and relative humidity. A weather station about 11 nautical miles from the accident site reported a temperature of 32 degrees F and dew point of 30 degrees F at the time of the accident. These weather conditions were conducive to the formation of serious carburetor icing at cruise power. A postaccident examination of the engine found no preaccident mechanical malfunctions or failures that would have precluded normal operation. It is likely the engine began to lose power due to carburetor ice and that the timely application of carburetor heat would have restored engine power.

Text from the NTSB. Open the NTSB docket for WPR11LA193 for the full record.