As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT, CREW SMELLED BURNING PLASTIC. UPON INVESTIGATION BY MAINTENANCE, FOUND THAT ALL OF THE FAN BLADES HAD BROKEN OFF AND WERE LAYING IN THE AUXILIARY HEATER ASSY. ONE BLADE MADE IT INTO THE HEATER COILS AND WAS BEING MELTED. INSTALLED NEW FAN BLADE ASSY. POST OPS CHECK WAS NORMAL. NO REASON OR CAUSE FOR BLADES COMING OFF WAS FOUND. (X)