On May 21, 2005, a North American NAVION (registration N8874H) was involved in an aviation accident near Emmett, ID. Investigators recorded the probable cause as: Air leaking into the fuel system through a worn fuel selector valve stem and a hardened and brittle fuel selector valve O-ring. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During cruise, an engine experienced partial power loss. Despite switching fuel tanks and using the boost pump, power was insufficient. The pilot attempted to land on a golf course but struck a pole on an adjacent street. Post-accident inspection revealed air leaks in the fuel selector valve.
Event Description
While operating in cruise flight, the engine experienced a partial loss of power. Although some power continued to be produced, it was insufficient to maintain level flight. In response, the pilot activated the fuel boost pump and selected a different fuel tank, but the condition did not improve. The pilot then proceeded to search for a suitable landing area. The only viable option identified was a golf course, but the aircraft came up short of its boundaries. As the pilot attempted to touch down on a street immediately outside the golf course, the airplane struck a pole.
Investigation Findings
A post-accident examination of the aircraft revealed a fuel system anomaly. Air was found to be leaking into the fuel system due to a worn fuel selector valve stem and a fuel selector valve O-ring that had become hardened and brittle. These conditions allowed air to enter the fuel supply, compromising engine performance.
Probable cause
Air leaking into the fuel system through a worn fuel selector valve stem and a hardened and brittle fuel selector valve O-ring.