What was found
MCN - MAJOR REPAIR - DURING C-04 CHECK EXFOLIATION CORROSION WAS FOUND ON AFT END OF Y503 DUMMY RAIL AT FR 16. MAINTENANCE REMOVED CORROSION AND FOUND MATERIAL LOSS TO BE OUT OF LIMITS, REMOVED AND REPLACED Y503 DUMMY RAIL AT FR 16 IAW A320 SRM 51-42-11 PG 23-28, FIG 9-12.