Casualties unknown

2003-07-20: Maule M-4 (N40344) — Kobuk, AK

Kobuk, AK, US

On July 20, 2003, a Maule M-4 (registration N40344) was involved in an aviation accident near Kobuk, AK. Investigators recorded the probable cause as: The pilot's inadvertent use of diesel fuel in a gasoline engine which resulted in a partial loss of engine power, and subsequent collision with trees during a forced landing after takeoff. 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 private pilot experienced a slow decrease in engine power after takeoff. Unable to maintain altitude, the airplane struck trees, suffering damage to wings, lift struts, elevator, and landing gear. Post-accident examination revealed the pilot had inadvertently fueled the airplane with diesel instead of gasoline due to a mislabeled storage drum.

Preflight and Departure

Before the accident flight, a private certificated pilot added 14 gallons of fuel to the airplane from a 55-gallon drum stored at his cabin. During the preflight inspection, the pilot drained the fuel sumps and found no water contamination. After departure, the engine power began to decrease slowly. The pilot noted that the engine did not exhibit roughness or unusual sounds, but the revolutions per minute (rpm) dropped to approximately 2,200 and the airplane started losing altitude.

Attempted Return and Collision

When the airplane was about 200 feet above the ground, the pilot initiated a turn to the north in an effort to return to the runway. However, the airspeed continued to decrease. The airplane subsequently collided with numerous trees. The collision caused damage to the wings, lift struts, elevator, and the right main landing gear.

Post-Accident Examination

Following the accident, the pilot examined the fuel that had been placed in the airplane. He discovered that the fuel was diesel fuel, not gasoline. The pilot reported that his storage drum was mislabeled, leading to the fueling error.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20030804X01255. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.