Amateur-built SQ-2 N58SQ accident near Soldotna, Alaska

Probable cause

A total loss of engine power due to carburetor icing, which resulted from the pilot's failure to use carburetor heat while operating in conditions conducive to the formation of carburetor ice.

NTSB analysis

The pilot reported that, while in cruise flight at about 4,000 ft mean sea level (msl), he advanced the throttle to initiate a climb, but the engine began to lose power. In an effort to regain power, he further advanced the throttle and propeller levers and switched the fuel selector to the left tank to no avail. He subsequently made a forced landing in a small gully, which resulted in substantial damage to the wings and fuselage.

When the pilot was asked if he applied carburetor heat after the loss of power, he stated that he did not, as there was no visible moisture in the area, and he thought carburetor ice would be unlikely.

A postaccident examination revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. According to a carburetor icing probability chart, the ambient conditions present at the time of the accident were conducive to the development of serious icing at cruise power. It is likely that the loss of engine power was the result of the formation of carburetor icing, and had the pilot applied carburetor heat, engine power would likely have been restored.

Text from the NTSB. Open the NTSB docket for ANC22LA064 for the full record.