As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE IN FOR C-CHECK, MAINTENANCE FOUND CORROSION (SSID W-1A) ON EXTERIOR OF LOWER CHORD AT BS 870 RBL 41. WHILE REMOVING WEB, FOUND CORROSION ON LOWER SIDE OF CHORD BEYOND LIMITS. REPLACED LOWER CHORD. WORK DONE IAW E.O. B727-5710-7413-A.