As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB, A LOUD BANG WAS HEARD IN THE AFT VENTRAL STAIRS FOLLOWED BY A LOWER AFT BODY OVERHEAT INDICATION. AIRCRAFT DUMPED FUEL AND RETURNED TO MSP AND LANDED WITHOUT INCIDENT. REPLACED TWO RUPTURED DUCTS IN AFT VENTRAL STAIR AREA AND PT2 LINES. PERFORMED LEAK CHECK OF PITOT STATIC SYSTEM AND PNEUMATIC SYSTEM, OPERATIONAL CHECK OK.