Champion 7GCBC N9117L accident near Weyers Cave, Virginia

Probable cause

A total loss of engine power on approach due to carburetor ice.

NTSB analysis

During the second landing of an instructional flight to obtain currency in tailwheel airplane takeoffs and landings. The first takeoff and landing were uneventful. During the second approach, while abeam the numbers on the downwind leg of the pattern, the pilot receiving instruction reduced engine power, applied carburetor heat, and began a descent. While turning from base leg to final, the instructor told the pilot to increase engine power to not fly below the proper glidepath; the pilot advised that the engine was not responding to throttle input.

The instructor took control of the airplane and lowered the nose to maintain airspeed. He then verified that the fuel, mixture, primer, switches, and carburetor heat controls were in the correct position. About 300 ft above ground level (agl), the instructor realized the airplane was too low to clear a road and guardrail just before the runway, so he chose to turn right to land in a field. During the landing, the airplane struck a wire fence, the right main landing gear collapsed, and the airplane came to rest on its right wing.

Postaccident examination revealed no airplane or engine anomalies that would have affected normal operation except that the carburetor heat control and valve were found in the mid-range position. An icing probability chart indicated “Serious Icing – glide power” for the recorded temperature and dew point about the time of the accident. Engine manufacturer service instructions included a caution to not use a mid-range position for carburetor heat control on aircraft, like the accident airplane, that were not equipped with a carburetor air temperature gauge.

The mid-range position of the carburetor heat control, along with the ambient temperature and dew point, could have resulted in carburetor ice after reducing engine power on approach, resulting in a total loss of engine power. However, the position of the carburetor heat control before the accident could not be confirmed due to impact damage to the airbox.

Text from the NTSB. Open the NTSB docket for ERA25LA189 for the full record.