As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FOUND CRACK ON FUSELAGE SKIN DURING C-CHECK. WHILE REMOVING FASTENERS FOUND CORROSION ON UPPER SKIN FWD OF CRACK, OPENED UP ENTIRE LAP JOINT AND REMOVED CORROSION ON UPPER SKIN. PERFORMED NDT IAW THE SRM AND FOUND 27 CRACKED COUNTERSINKS. CUTOUT ALL DAMAGE AND INSTALLED A REPAIR IAW BOEING MESSAGE 1-533791124 AND ACO-085315.