Amateur-built CAVALIER SA102.5 N115RH accident near Salem, Iowa

Probable cause

The partial loss of engine power due to the formation of carburetor ice.

NTSB analysis

About 25 minutes prior to reaching the intended refueling destination, the pilot noticed a drop in engine rpm. The pilot applied carburetor heat, the engine rpm increased, and he turned the carburetor heat off. All other engine instruments and indications appeared normal. During the descent, the engine rpm dropped again, and the pilot attempted to resolve the problem by again applying carburetor heat, changing throttle positions, and switching fuel tanks; however, he was unsuccessful. Unable to maintain altitude, the pilot performed a forced landing to a cornfield. During postaccident examination of the airplane, fuel was noted in the airframe fuel tanks, and mechanical continuity was established throughout the engine. The airplane was operating in conditions conducive to serious carburetor icing at glide power at the time of the accident. It is possible that, when the engine lost partial power during the descent, the carburetor heat was not effective, because the engine was operating at a low power setting and was not producing sufficient heat to melt the ice.

Text from the NTSB. Open the NTSB docket for CEN11LA539 for the full record.