Cessna 172 N6474B accident near Fulton, Missouri

Probable cause

The partial loss of engine power due to water contamination in the fuel system.

NTSB analysis

The private pilot and two passengers were conducting a local sightseeing flight when the engine "sputtered ever so slightly" and then regained power. Three to 5 seconds later, engine power dropped to about 700 rpm. The pilot checked the engine controls in an attempt to regain engine power; when power was not restored, he initiated a forced landing to a field. During the forced landing, the airplane landed about 3/4 down the length of a field and impacted adjacent trees.

During an initial examination, about 1 ounce of water was found in the gascolator. Continuity was established from the cockpit engine controls to the respective engine components. Fuel was found in the carburetor bowl and in the wing fuel tanks. A follow-up engine examination and functional test run did not produce any anomalies that would have prevented normal operation and production of rated horsepower. It is likely the water contamination found in the gascolator resulted in the partial loss of engine power.

Text from the NTSB. Open the NTSB docket for CEN17LA241 for the full record.