As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING D-CHECK AT SIN, CENTER WING TANK, LOWER SKIN ABOVE NR 1 ACM FOUND CORRODED. LEVEL 1. CORROSION WAS BLENDED OUT WITH A MACHINED FINISH. THE BLENDED AREA WAS HFEC INSPECTED AND FLAP/SHOP PEENED. ALODINE PRIMER AND BMS 3-23 CORROSION INHIBITING COMPOUND WAS APPLIED TO THE BLENDED AREAS PER 747 SRM 57-10-01 FIGURE 2. (M)