As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LT LA7143 - MIA/ASU-ATB, AFTER TAKEOFF, CREW ADVISED THAT THEY WERE UNABLE TO PRESSURIZE THE AIRCRAFT. AFTER ABNORMAL CHECKLIST ACCOMPLISHED, CHECK OF MAIN DECK REVEALED NO ABNORMALITIES. DUMPED 80 KGS OF FUEL AND RETURNED TO MAI WAS UNEVENTFUL. MAINTENANCE FOUND A I CRACK IN R5 MAIN ENTRY DOOR. REPLACED R5 MED AND PRESSURIZATION CONTROLLER. PRESSURIZATION CHECK NORMAL. (M)