As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING A MAINTENANCE FUNCTION SEVERE CORROSION WAS DISCOVERED ON THE BOTTOM OF THE WING SPAR ENTRE SECTION. THIS SECTION OF THE SPAR HAS HIGH DENSITY FOAM GLUED TO THE SPAR WHICH PREVENTS ADEQUATE INSPECTION. THE CORROSION WAS SUCH THAT THE WING SPAR CENTRE SECTION REQUIRED REPLACEMENT. (TC NR 20070912005)