On July 19, 1997, a Cessna 170 (registration N4292V) operated by Robert E. Stone was involved in an aviation accident near Graham, WA. Investigators recorded the probable cause as: Inadequate aircraft preflight by the pilot-in-command, and water contamination in the fuel resulting in a loss of engine power. A factor was a power transmission line in the forced landing area. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During cruise, engine RPM dropped to 800 without throttle reduction. Forced landing over power lines resulted in right main landing gear collapse. Post-accident examination revealed water-contaminated fuel.
Accident Sequence
Approximately nine minutes after takeoff, while in cruise flight, the engine RPM dropped to 800 without any reduction in throttle setting. Despite the pilot's attempts at corrective actions, the RPM did not recover. The pilot executed a forced landing, crossing over power lines and touching down in a soft field. During the landing, the aircraft's right main landing gear collapsed.
Examination Findings
The pilot reported that 20 gallons of fuel were on board at the time of takeoff. On-site and follow-up examinations of the aircraft revealed that the left wing fuel tank was empty. The right wing tank contained 11 to 12 gallons of fuel, which was contaminated with approximately 3 pints of water. Additionally, water was present in the carburetor.
Preflight Actions
The pilot reported that his preflight actions included checking the oil and performing a sump drain.