As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FUSELAGE SKIN IN THE KEEL AREA BETWEEN FS 661 & 727 WAS FOUND WITH CRACKS AT SEVERAL OF THE ACCESS CUTOUTS IN THE PANEL. THE CRACKING IS TYPICAL OF BAC S/B 737-53-1104. THE SKIN PANEL WAS REMOVED AND A MODIFIED PANEL MANUFACTURED AND INSTALLED. THE REPAIR WAS ACCOMPLISHED PER THE S/B AND PER ER/A 386067-14.