This August 2007 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Aircraft: Piper Super Cub.
Location: Anaktuvuk Pass, Alaska.
Aircraft damage: Substantial.
What reportedly happened: The commercial pilot was attempting to land landing the tundra tire-equipped, tailwheel airplane at an unimproved, off-airport site. During the base leg of the approach for landing, the engine lost power. The pilot initiated a emergency descent. The airplane collided with terrain.
The airplane’s owner reported that he had observed the preflight inspection, and watched the pilot sump the fuel tanks, finding a small quantity of water in the tanks. While inspecting the airplane after the accident, the owner said he found water in the airplane’s gascolator, carburetor, and fuel lines. He said the airplane was fueled from drums with filters, and it had rained during the preceding days. He said he suspected water contaminated fuel was the cause of the engine stoppage. After refueling the airplane with clean fuel, the engine started and ran without any problems.
Probable cause: The pilot’s inadequate preflight inspection, which resulted in a loss of engine power during approach due to water contaminated fuel.
For more information: NTSB.com