As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INFLIGHT EXPERIENCED ELECTRICAL BURNING ODOR AFTER A GRINDING SOUND. RETURNED TO DEPARTURE. AT THE GATE NOTICED THE CIRCUIT BREAKER FOR THE AVIONIC VENT EXTRACT FAN TRIPPED; INSPECTED THE ACFT FOR EVIDENCE OF ANY ELECTRICAL BURNING SIGNS. NOTED EXTRACTION FAN 18HQ BURNED OUT CAUSING THE ELECTRICAL ODOR NOTED BY FLIGHT CREW. REMOVED & REPLACED THE FAN IAW AMM 21-26-51. AVEC TESTED OK IAW AMM 21-26-00, AND TSM 05-50-00.