Casualties unknown

1998-03-12: Mooney M20K (N3556H) — Klamath Falls, OR

Klamath Falls, OR, US

On March 12, 1998, a Mooney M20K (registration N3556H) was involved in an aviation accident near Klamath Falls, OR. Investigators recorded the probable cause as: The pilot's inadequate preflight which failed to detect water contaminated fuel that subsequently led to fuel icing at altitude, blockage of fuel lines which resulted in fuel starvation. A related factor was the dark night conditions. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

A pilot reported water contamination in the left fuel tank led to engine roughness and subsequent loss of power during a night flight, forcing a landing in an unlighted area.

Incident Details

The pilot reported that the aircraft had been parked outdoors during the winter months and was not flown much. Three days prior to the accident flight, during a preflight inspection, he observed a puddle of water under the aircraft's low point. He noted that this was unusual because the tarmac was dry. He drained the fuel lines using the gascolator without testing the drained fuel, but he tested all four fuel tanks. The right tanks tested fine, while the two left tanks contained an estimated total of one gallon of water. The subsequent flight, which included a fuel stop, was uneventful.

Preflight Inspection on the Day of the Accident

On the day of the accident, the pilot again preflighted the aircraft and drained approximately half a cup of water from the left side. The first leg of the trip was flown at an altitude of 12,000 feet MSL, and the aircraft was refueled before continuing.

Accident Flight

After departure, the aircraft was cleared to climb to flight level 240. The pilot reported the outside air temperature as -27 degrees Celsius. Shortly after reaching altitude, he noticed a slight engine roughness. He attempted several troubleshooting procedures to resolve the issue but was unsuccessful. When the aircraft was approximately 5 to 7 miles from the airport, the engine ceased developing power. The pilot executed a forced landing under dark night conditions to an unlighted landing site. He stated that he descended into total blackness.

Post-Accident Examination

Following the accident, an FAA Inspector examined the aircraft and drained several ounces of water from the left wing tank. No anomalies were noted that would have precluded normal operation.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001211X09777. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.