As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GNDED. AIR INTERRUPT, EMER WAS DECLARED, LANDING UNEVENTFUL & ACFT NOT OVERWEIGHT. DURING CRUISE CREW REPORTED WHITE SMOKE IN FWD CABIN AT SEAT 3A LOWER VENT. FOUND FWD CARGO HEATER CB TRIPPED. AN INSPECTION OF THE FWD CARGO HEATER FOUND FAULTY HEATING ELEMENT. R & R FORWARD CARGO HEATER IAW AMM 21-41-00.