What was found
DURING REFURBISHMENT OF THE WING CENTER SECTION WING WALKWAY BOXES, AN INSPECTION WAS CONDUCTED TO COMPLY WITH AD 2002-26-02. LOWER SKINS OF THE WALKWAY BOXES HAD BEEN REMOVED TO PROVIDE ACCESS FOR REFURBISHMENT, THIS PROVIDED UNIMPEDED ACCESS TO THE ENTIRE CENTER SECTION. CORROSION WAS FOUND ON THE RIGHT SIDE INBOARD REAR FORMER RIB LOCATED BEHIND THE REAR SPAR. CORROSION HAD SEVERELY DAMAGED THE RIB BEYOND AC43-4A CRITERIA REQUIRING REPLACEMENT. NEW RIB WAS PURCHASED AND INSTALLED. NO OTHER CORROSION WAS FOUND IN THE CENTER SECTION. THE ENTIRE CENTER SECTION WAS CLEANED AND PRIMED PRIOR TO REINSTALLATION OF LOWER SKIN.