What was found
CENTER WING BOX UPPER SKIN IS CORRODED IN SEVERAL LOCATIONS AROUND FASTENER HEADS BETWEEN BS 696 THROUGH 715, LBL 43 THROUGH LBL 59. VIEW FROM UNDER CABIN FLOOR BOARDS. REPARIED CENTER WING BOX UPPER SKIN BS 696 THROUGH 715, LBL 43 THROUGH LBL 59 IAW PRI 540753-14, REV 0-REV 2 AND ER/A 540753-14, REV ORIGINAL ASSOCIATED ER/A 14-540753 ADDED FOR AC 9553.