Amateur-built CH-750 N8681 accident near Morristown, Minnesota

Probable cause

A total loss of engine power due to fuel vapor lock. Contributing to the loss of engine power were the corrosion of the spark plugs and the spacing of the electrode gaps.

NTSB analysis

The private pilot reported that he had started, warmed up, and then shut down the engine about 1 hour before the accident flight. Shortly after takeoff for the personal flight, the airplane's engine lost total power. Subsequently, the pilot conducted a forced landing on a hill, which resulted in substantial damage to the nose landing gear, fuselage, and left wing.

The pilot said that he had fueled the airplane that morning with 82-octane automotive fuel that he had recently purchased from a service station. However, postaccident examination revealed that the fuel was yellow in color and smelled like "aged" automobile fuel. The top spark plugs appeared aged, and the electrodes were corroded, which could have affected engine performance. The airplane was not equipped with a fuel vapor return line to prevent fuel vapor lock. Given that old automotive fuel was found in the fuel system and that a fuel vapor return line had not been installed, it is likely that the engine lost power due to vapor lock. It is also likely that the corrosion of the spark plugs and the spacing of the electrode gaps contributed to the loss of engine power.

Text from the NTSB. Open the NTSB docket for CEN17LA021 for the full record.