Incident
The pilot of the aircraft reported that the right engine failed after landing at the Wichita Falls, Texas airport. A witness observed the pilot attempting to restart the engine several times. During the final restart attempt, the right wing exploded.
Damage
Damage was concentrated in the right wing, between the engine nacelle and the main fuel tank. No fire was associated with the explosion. Examination of the wreckage indicated that the explosion originated in the engine area and emanated from within the wing.
Fuel Management
The pilot stated that during the flight, he had taken off using the main fuel tanks, then switched to the auxiliary tanks. Prior to landing, he switched back to the main tanks. According to the FAA inspector at the scene, the main fuel tanks were found "overfilled beyond the filler openings."
Aircraft Manual
The pilot operating handbook requires substantial operating time on the main tanks before switching to the auxiliary tanks. Additionally, fuel overflow from the engines returns only to the main tanks.