As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE AIRCRAFT WAS IN FOR HEAVY CHECK, LEVEL 2 CORROSION WAS FOUND ON THE REAR FUSELAGE DRAIN, MID 2 DRAIN AND MID 1 DRAIN FAIRING (SHOWED EVIDENCE OF CORROSION BUILD UP). MAINTENANCE REPAIRED CORROSION BUILD UP TO REAR FUSELAGE MID 1 & 2 DRAIN FAIRINGS IAW EMB 170 SRM 51-73-11. REF ACE REPAIR DOCUMENT AF610 FOR MATERIAL PARTS USED. ON PO 009312-2012.