Cessna 140 N2199N accident near Wilkeson, Washington

Probable cause

A partial loss of engine power during takeoff due to water contamination in the fuel system.

NTSB analysis

The pilot reported that he had washed the airplane the day prior to the accident. On the day of the accident he determined during the preflight inspection that the fuel and induction systems were not contaminated with water. The engine run-up was uneventful; however, when the airplane was about halfway down the runway during takeoff, the engine began to sputter. The pilot verified the positions of the fuel selector handle and carburetor heat control and pumped the throttle, which sustained engine power momentarily. The airplane could not sustain flight and the pilot subsequently force-landed it in nearby trees. During the postaccident engine inspection, no operational anomalies were noted. The pilot further reported that on previous occasions after washing the airplane the engine experienced similar instances of momentary power loss. It is likely that, although the pilot conducted an extensive preflight inspection, undetected water contamination in the fuel system resulted in a reduction of power during takeoff.

Text from the NTSB. Open the NTSB docket for WPR11LA369 for the full record.