Incident Overview
A pilot flying a single-engine airplane experienced an engine failure while returning to Knoxville Downtown Island Airport. The pilot had topped off both fuel tanks before departing Knoxville earlier, with 12 gallons in the left tank and 39 gallons in the right tank. The airplane was equipped with extended-range tanks holding a total of 51 gallons.
Flight Sequence
The outbound flight to Auburn-Opelika Airport was uneventful. On the return trip, the pilot switched the fuel selector to the right tank immediately after departure to compensate for the unequal fuel quantities. Approximately 8 miles east of Knoxville Downtown Island Airport at an altitude of 2,500 feet, the engine began to sputter. The pilot moved the fuel lever to the "both" position; the engine briefly fired but then stopped. The pilot was unable to restart the engine and reported the failure to air traffic control.
Descent and Impact
The pilot configured the airplane for a slow descent with full flaps but could not see the terrain due to darkness. The right wing struck a tree, and the airplane came to rest in a small field.
Wreckage Examination
Post-accident examination revealed that the outer section of the right wing and the wing strut had detached. The nose gear was also detached, and the propeller sustained damage. Blue fuel stains were observed on the top of the left wing and the left side of the fuselage. The left fuel cap was missing; a search of the crash path and surrounding area did not locate it. No usable fuel was found in either tank.
Fuel Caps
The airplane was fitted with aftermarket gas caps installed under Supplemental Type Certificate (STC) SA2376CE. These caps are designed to be twisted clockwise until they lock. The caps are visible from the ground but lack reference markings to indicate whether they are properly locked.
Pilot Statement
In the pilot's post-accident interview and written statement, he did not mention securing the fuel caps during the preflight inspection.