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ANC03LA083 · Maule M-4

20 Jul 2003 · KOBUK, AK, United States

Maule M-4 · Accident: partial loss of engine power (non-mechanical) during initial climb

From Dahl Creek Airport (DCK) to Fairbanks International Airport (PAFA)

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Event

NTSB case
ANC03LA083
Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
Accident
InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
Completed
API-reported fatalities
0 · all aircraft and ground
Ground fatalities
Unknown
OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
General aviation
WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
Visual Meteorological Cond

Maule M-4

Aircraft type
Maule M-4
Category
Airplane
RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
N40344
Operator
Unknown
Onboard fatalities
Unknown
Route
From Dahl Creek Airport (DCK), KOBUK, AKTo Fairbanks International Airport (PAFA), Fairbanks, AK
Aircraft age
Not recorded
Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
Part 91: General Aviation
Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
Initial climb
First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
Partial loss of engine power (non-mechanical)
Also codedOther events the NTSB coded in the sequence, such as a wire strike after a loss of power. Flight Findings uses them for its kinds of event. Glossary
Fuel contamination; Tree(s)
DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
Substantial

Cause areas

  • Fluid, fuel › Contamination, other than water
  • Pilot in command › Fuel supply, inadvertent use

Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.

NTSB narrative

Prior to departure on the accident flight, the private certificated pilot fueled the airplane with 14 gallons of fuel from a 55 gallon drum that he stored at his cabin. He conducted a preflight of the airplane, which included draining the airplane's fuel sumps, and found no water in the sumps. After liftoff, the engine power began to decrease slowly. The pilot said the engine did not have any roughness or unusual sounds, but the rpm decreased to about 2,200 and the airplane began to lose altitude. About 200 feet above the ground, the pilot began to turn to the north in an effort to return to the runway, but the airspeed was decreasing. The airplane collided with numerous trees and sustained damage to the wings, lift struts, elevator, and the right main landing gear. Following the accident, the pilot examined the fuel from the airplane. He said he discovered that the fuel he placed in the airplane before departure was diesel fuel. He reported that his storage drum was mislabeled.

Probable cause

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. A factor contributing to the accident was the pilot's inadequate preflight inspection of the airplane that failed to detect the presence of diesel fuel in the fuel supply.

Verbatim NTSB analysis and probable cause from the NTSB dataset

Sources

NTSB record ANC03LA083
Event ID
20030804X01255
Case number
ANC03LA083
Dataset
historical-pre2008
Source SHA-256
89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
  • Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
  • Filled from the NTSB case API where the bulk record had no value: investigation status, coordinates. Values present in the bulk record are kept.
  • The date is the local date, which is the same as the UTC date the NTSB stores.
  • API snapshot SHA-256: 0ebc7308b3ab7bee4a5e226f43f14a7ef30791b6a754762af4085c56e98116a9; retrieved 2026-09-21T19:25:01.734Z.