Casualties unknown

Pilot encounters water in fuel during preflight, leading to engine failure and forced landing (N9191H)

St. Mary's, AK, US

On June 21, 1982, a Cessna 172 (registration N9191H) operated by Western Yukon Air was involved in an aviation accident near St. Mary's, AK. Investigators recorded the probable cause as: The pilot's decision to fly with water in the fuel system, which caused engine failure. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 2 related events involving the same aircraft type or operator are linked below.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-06-20Data APIEditorial standards

A pilot detected significant water contamination in the fuel system before takeoff but proceeded with the flight. The engine failed shortly after departure, forcing an emergency landing on a road.

What happened

The incident began during the preflight inspection when the pilot discovered considerable amounts of water within the aircraft's fuel system. Despite this critical finding, the pilot elected to proceed with the planned flight. During the takeoff roll, the engine suddenly quit, resulting in a loss of power.

With insufficient runway remaining, the pilot executed an intersection takeoff, utilizing less than half of the available runway length. Following the engine failure, the pilot attempted to execute a forced landing on a nearby road. However, due to the presence of a truck on the roadway, the pilot diverted and landed in the dirt alongside the road instead.

Upon impact, the aircraft nosed over. After the accident, when the aircraft was turned right side up, investigators confirmed that both the gascolator and the wing tank drains were full of water, corroborating the initial preflight observation.

The investigation

Post-accident examination of the aircraft revealed significant fuel contamination. The physical evidence collected after the aircraft was returned to an upright position showed that the gascolator and wing tank drains contained substantial amounts of water. This finding aligned with the pilot's earlier report of considerable water in the fuel during preflight.

Findings

The primary factors contributing to this accident were the presence of water in the fuel system and the decision to fly despite knowing about the contamination. The engine failure was directly caused by fuel starvation due to this contamination. Additionally, the use of an intersection takeoff contributed to the lack of adequate runway distance for recovery.

Safety message

Pilots must ensure that fuel is free of water and contaminants before flight. If water is found during preflight, it should be drained completely before attempting to operate the aircraft.

Probable cause

The pilot's decision to fly with water in the fuel system, which caused engine failure.

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Frequently asked questions

What happened in the 21 Jun 1982 Cessna 172 accident near St. Mary's, AK?

A pilot detected significant water contamination in the fuel system before takeoff but proceeded with the flight. The engine failed shortly after departure, forcing an emergency landing on a road.

What aircraft was involved and where did it happen?

The accident on 21 Jun 1982 involved a Cessna 172, registration N9191H, operated by Western Yukon Air, at St. Mary's, AK.

What was the probable cause of the accident?

The pilot's decision to fly with water in the fuel system, which caused engine failure.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20020917X02646. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.