Casualties unknown

Forced Landing After Engine Failure During Aerial Moose Survey; Fuel Sample Contains Water (N8578D)

Glennallen, AK, US

On May 23, 1998, a Piper PA-18 (registration N8578D) was involved in an aviation accident near Glennallen, AK. Investigators recorded the probable cause as: The pilot's inadequate preflight of the airplane's fuel system, and presence of water in the fuel system. 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 2026-06-10Data APIEditorial standards

A pilot conducting an aerial moose survey for the State of Alaska lost engine power at 500 feet AGL. A forced landing resulted in tree collision and substantial damage. A fuel sample showed water contamination.

Incident Overview

A certificated commercial pilot and a passenger, a wildlife biologist employed by the State of Alaska, were conducting an aerial moose survey. The pilot reported that while in cruise flight at about 500 feet above ground level, all engine power was lost. Attempts to restore engine power were unsuccessful, and the pilot turned the airplane to avoid rising terrain. During the subsequent forced landing, the airplane collided with trees.

Aircraft Damage

The airplane sustained substantial damage to the wings and fuselage.

Post-Accident Examination

A Federal Aviation Administration (FAA) airworthiness inspector examined the airplane wreckage and obtained a fluid sample from the fuel system gascolator. The sample exhibited two obvious layers of separated liquid. The top layer consisted of a bluish liquid, consistent with the color of 100LL aviation fuel. The lower layer consisted of a clear liquid that appeared to be water. The National Transportation Safety Board (NTSB) investigator-in-charge tested the clear fluid with water finding paste, and the sample tested positive for water.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001211X09974. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.