Piper PA-28-161 N20GG accident near Rapid City, South Dakota

Probable cause

The loss of engine power during climb due to carburetor icing. Contributing to the accident was the limited travel of the carburetor heat valve which prevented application of maximum carburetor heat.

NTSB analysis

During an instrument instructional flight, the airplane encountered clouds as it climbed through about 4,500 feet mean sea level (msl) and subsequently experienced a partial loss of engine power as it climbed through about 6,500 feet msl in conditions that were conductive to serious carburetor icing conditions. The flight instructor turned on the carburetor heat at the onset of the power loss, which resulted in an additional loss of engine power and a rough-running engine. The flight instructor subsequently turned off the carburetor heat because the airplane was unable to maintain altitude to return to the departure airport. The engine then experienced a total loss of power, and the pilot performed a forced landing. No engine anomalies were noted during a postaccident engine run; however, the carburetor heat valve only moved about 3/4 of its travel, so maximum carburetor heat was not available.

The flight instructor stated that he and the pilot receiving instruction reviewed the weather conditions as part of their preflight planning and determined that the weather was satisfactory for the intended flight. The instructor further stated that the carburetor heat appeared to be functioning during the pretakeoff engine run-up. The weather conditions encountered during the climb in the clouds were conducive to serious carburetor icing at cruise climb power.

Text from the NTSB. Open the NTSB docket for CEN12LA175 for the full record.