As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - CREW REPORTED A BURNING ODOR IN CABIN AFTER TAKEOFF. EMERGENCY DECLARED FLIGHT RETURNED DFW LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. FOUND FORWARD CARGO HEATER DUCT ASSEMBLY FAULTY. REPLACED DUCT. SYSTEM GROUND CHECK NORMAL OPERATION.