What was found
MAIN CABIN AFT WET AREA, INTERCOSTAL HAS CORROSION ON UPPER SURFACE BETWEEN BS 947.5 AND BS 967 APPROX RBL50. REMOVED CORROSION FROM INTERCOSTAL, UPPER SURFACE, ORIGINAL THICKNESS .125", MATERIAL REMOVED .074", REMAINING MATERIAL .051", FOUND TO BE OUT OF SRM LIMITS IAW B737 SRM 53-70-51. REMOVED AND REPLACED INTERCOSTAL IAW B737 DWG NO. 147A5760 REV- .