As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR RETURN, FLIGHT 5069, PILOTS REPORTED A STRONG BURNING ODOR DURING FLIGHT. MAINTENANCE PERFORMED OPERATIONAL CHECKS OF BOTH ENGINES ON THE GROUND WITH NO FAULTS FOUND. SUBSEQUENT OPERATIONAL CHECK FLIGHT WAS CONDUCTED WITH NO FURTHER REPORTS.