This December 2007 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Aircraft: Mooney M20C; Location: Phillipsburg, Kan.; Injuries: 1 Serious, 1 Minor; Aircraft damage: Substantial.
What reportedly happened: The airplane was in cruise flight in VFR conditions at night at 8,500 feet MSL when the engine lost power. The pilot requested assistance from ATC and was given vectors to the nearest airport, which was eight miles away. The airplane lacked sufficient altitude to glide to the airport so the pilot attempted to land in a snow-covered field. The airplane collided with trees and terrain and caught fire.
During the post-accident examination, disassembly of the carburetor revealed a brown gooey substance in the inlet fuel screen and float valve, which restricted the movement of the valve. Analysis of the substance by NTSB’s materials laboratory revealed it to be most likely an inorganic compound. The analysis of the various samples revealed high peaks of carbon, while other samples had high peaks of sulfur, and still others high peaks of calcium silicon. The laboratory report noted that when aviation gasoline evaporates, various additives, such as anti-knock compounds, dyes, inhibitors and anti-icing compounds, remain in the form of a gum.
Probable cause: Total loss of engine power due to contamination of the carburetor and total blockage of the fuel inlet screen.
For more information: NTSB.gov
