What happened
On September 12, 2024, at approximately 12:05 CDT, a Piper PA-12, registration N7878M, was performing a personal flight under Part 91 regulations when the engine lost power. The aircraft was in a cruise descent at 2,100 feet mean sea level toward Cumberland Municipal Airport (CBE) in Wisconsin when the engine began to sputter.
The pilot attempted to restore power by moving the throttle to the full-forward position and setting the mixture to full-rich. While the engine briefly resumed operation for 5 to 10 seconds, it failed a second time. Due to the low altitude, the pilot performed an immediate forced landing in a nearby cornfield. The pilot was not injured, but the aircraft sustained substantial damage to the fuselage structure, engine mounts, and the right wing.
The investigation
Mechanical examination of the engine and fuel system showed no evidence of preimpact mechanical malfunction. The fuel tanks contained ample fuel, and no water or particulate contamination was found in the fuel system. Internal engine components, including the crankshaft, valves, and pistons, were inspected via borescope and showed no anomalies. Both magnetos produced spark, and the oil filter and carburetor fuel inlet screen were free of contamination.
Investigators found that the throttle cable was broken at the clevis, though the carburetor throttle remained in a wide-open position. The mixture control was in the full-rich position, and the mechanical stop-pin for the mixture control was fractured. While the carburetor heat control was found in the off position, the airbox sustained impact damage that prevented the movement of the carburetor heat valve.
According to FAA Special Airworthiness Information Bulletin CE-09-35, the temperature and dew point at the time of the accident indicated a susceptibility for carburetor icing at glide engine power settings.