What was found
(CAN) DURING INSPECTION TO COMPLY WITH AD 2003-21-01 SEVERE CORROSION FOUND ON FORWARD END OF RIB, AFT OF REAR SPAR, IN THE RT CENTER SECTION, BETWEEN THE FUSELAGE AND WING. THE CORROSION WAS NOT READILY NOTICEABLE UNTIL INSTALLATION OF INSPECTION PANELS SK 80-2 IAW SB 31 REV 1. THIS ALLOWED ACCESS TO THIS AREA WHICH OTHERWISE IS HARD TO SEE, EVEN THOUGH THE WINGS WERE REMOVED TO COMPLY WITH THE INSPECTION REQUIREMENTS OF 2003-21-01.