Amateur-built SONEX N293SX accident near Waxhaw, North Carolina

Probable cause

The pilot/owner/builder’s improper routing of the engine’s crankshaft position sensor cable next to the engine’s exhaust system, which resulted in a total loss of engine power in flight.

NTSB analysis

About 15 to 20 minutes after establishing the airplane in cruise flight, the pilot, who was also the owner/builder of the experimental amateur-built airplane, noticed that the engine rpm had dropped from the previously established 2,600 to 1,800. The engine continued to operate at this reduced power setting for about 30 to 60 seconds before it completely stopped producing power. The pilot subsequently performed a forced landing into trees, which resulted in substantial damage to the airframe. Postaccident examination of the engine revealed that the cable providing power to the crankshaft position sensor was routed next to the exhaust system and that it had melted. Subsequently, one of the wires electrically shorted to the engine block, which rendered the electronic fuel injection system inoperative. Replacement of the damaged cable restored the fuel injection system to normal function.

Text from the NTSB. Open the NTSB docket for ERA13LA405 for the full record.