As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) THE FUEL SYS HEADER TANK BOTTOM WAS DESIGNED SO ALL CONTAMINANTS WOULD DRAIN TO THE LOWEST POINT OF THE TANK WHERE THERE IS A DRAIN POINT. DURING MFG THE WELDING OF THE TANK BOTTOM CAUSED THE MATERIAL TO WARP CAUSING POCKETS TO FORM WERE CONTAMINANTS COULD COLLECT AND NOT DRAIN FROM THE TANK . CONTAMINANTS, WATER FORMED IN THE VOIDS OR POCKETS AND CORRODED THE TANK TO A POINT OF FAILURE.