This December 2008 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: Lancair 360. Injuries: None. Location: Owensboro, Ky. Aircraft damage: Substantial.
What reportedly happened: During the first 20 minutes of flight, the fuel selector was set to the main tank. The pilot then switched the selector to the left wing tank, and then to the right tank during the flight. Approximately 20 minutes after switching back to the left tank, the engine lost power.
While performing the emergency checklist the fuel selector was found to move freely with little resistance. Attempts to restart the engine were unsuccessful, and the pilot made a forced landing to a field.
In a statement written to the National Transportation Safety Board, the pilot said he knew the main tank fuel gauge was not working and that if it were operational it would have alerted him to the fuel selector valve control failure.
Examination of the airplane revealed that the center fuel tank had a capacity of 10 gallons of fuel and it was not breached. This tank was found empty of fuel. Further inspection of the fuel selector valve and handle revealed that a cotter pin used to secure the handle to the shaft which turns the valve was sheared. This resulted in movement of the fuel selector handle not changing the position of the valve and remaining on the main fuel tank position.
Probable cause: The loss of engine power due to fuel starvation. Contributing to the accident was the failure of the fuel selector valve cotter pin and the inoperative main fuel tank gauge.
For more information: NTSB.gov
It looks like a poor selection of fuel valve & handle. The valve shaft should be keyed, squared, or splined so that the handle could not slip or rotate on the shaft. The cotter pin should be used only to hold the handle on the shaft.