What was found
MCN - MAJOR REPAIR - DURING C-03 CHECK CORROSION WAS FOUND ON UPPER AND LOWER SURFACE OF CABIN FLOORBEAM AT FR 66-4, Y765. MAINTENANCE REMOVED DAMAGED FLOORBEAM AT FR 66-4, Y765; FABRICATED A REPLACEMENT FLOORBEAM; INSTALLED REPAIR PART IAW A320 SRM 51-42-11, PG. 6-7.