Amateur-built RV4 N924WZ accident near Shelbyville, Kentucky

Probable cause

The partial loss of engine power due to carburetor icing. Contributing to the accident was the pilot’s failure to effectively use carburetor heat.

NTSB analysis

Following several uneventful touch-and-go-landings, the private pilot refueled the airplane and returned to his home airport. During the approach for landing, the pilot saw wildlife on the runway, so he conducted a low pass over the runway; however, when he applied full throttle to climb, the engine did not produce full power. The pilot continued to climb the airplane with the intention of staying in the airport traffic pattern and making a full stop landing. Continuing through the pattern, he applied carburetor heat, then turned it off again. The airplane began sinking fast on final approach and impacted terrain short of the runway, resulting in substantial damage. A postaccident examination of the engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation.

The atmospheric conditions at the time of the accident were conducive to serious carburetor icing at glide power settings. After observing the loss of engine power during the climb out from the low approach, the pilot applied carburetor heat briefly, then, due to low altitude and sink rate, he turned off the carburetor heat to reduce the loss of power. It is likely that the carburetor accumulated ice during the low approach, which resulted in the observed partial loss of engine power, and the brief application of carburetor heat was insufficient to clear the ice from the carburetor and restore engine power.

Text from the NTSB. Open the NTSB docket for ERA16LA281 for the full record.