Amateur-built SONEX N68VF accident near Palatine, New York

Probable cause

A total loss of engine power for reasons that could not be determined because a test run and partial teardown of the engine did not reveal any anomalies.

NTSB analysis

The pilot stated that the noncertificated engine in his experimental, amateur-built airplane had been indicating low or no oil pressure. He returned the engine to the manufacturer and received an overhauled engine, which he operated for about 30 hours uneventfully. On the day before the accident, the pilot performed a routine 25-hour oil change and valve adjustment and noted no anomalies. On the day of the accident, the pilot departed a grass airstrip for a local flight with 8 gallons of fuel. He overflew the airstrip once and then performed an approach with the intention to land; however, the airplane was too high, so the pilot performed a go-around. During the go-around, the pilot heard two "pops," and the engine lost total power. The propeller did not windmill and came to a complete stop. The airplane was at a low altitude, and the pilot chose to land in a cornfield rather than try to turn back to the runway. During the landing, the right main landing gear lodged in mud, and the airplane nosed over. During a test run, the pilot was able to rotate the propeller and get compression on all four cylinders. He then started the engine, and it ran without hesitation. After shutdown, the pilot removed all of the cylinders and did not observe any preimpact mechanical malfunctions that would have precluded normal operation. The weather conditions were conducive to the accumulation of serious carburetor icing at cruise power. However, the engine was equipped with a flatslide aerobatic carburetor, which was not susceptible to carburetor ice due to the location that it was mounted to the engine. The reason for the engine power loss could not be determined.

Text from the NTSB. Open the NTSB docket for ERA14LA018 for the full record.