As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FUEL SELECTOR VALVE SEIZED IN THE (OFF) POSITION DURING A ROUTINE FUEL TANK SWITCHOVER. FAILURE CAUSED BY CORROSION ON SELECTOR VALVE SHAFT WHERE IT PASSES THROUGH THE UPPER VALVE HOUSING. POOR DESIGN. NO PROVISION MADE TO PREVENT SPILLED LIQUIDS OR MOISTURE FROM CARPET FROM ENTERING UPPER HOUSING VALVE SHAFT BORE. (K)