What was found
MAIN CABIN INTERCOSTAL UPPER SURFACE HAS CORROSION AT BS307 LBL12 AS MARK. GROUNDED - YES. REMOVED CORROSION IAW B737-800 51-10-02. ORIG THICK 0.125, REMOVED 0.060, REMAINING THICK 0.065 OUT OF LIMITS IAW B737-800 SRM 53-10-51. REMOVED INTERCOSTAL IAW B737-800 SRM 51-40-02. DRILLED TO FIT NEW INTERCOSTAL IAW B737-800 SRM 51-40-05 AND BAC DWG 141A5600 REV N INSTALLED NEW INTERCOSTAL IAW B737-800 SRM 51-40-02 AND BAC DWG 141A5600 REV N.