As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
JUST AFTER TAKEOFF, THE UPPER OUTBOARD NACELLE ACCESS PANEL ABOVE THE NR 1 ENGINE SEPARATED 521 FT. NO CONTROL PROBLEMS WERE NOTED. DUMPED 213,000 LBS OF FUEL AND DIVERTED TO MSP WITHOUT FURTHER INCIDENT. REPLACED PANEL (P/N 65814964-39).