As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CENTRIFUGAL FAN ASSY CAME APART, SHED ALL THE BLADES. POSSIBLE THAT THE FAN WAS OUT OF BALANCE. POSSIBLE THAT THE FAN WAS THROWN OUT OF BALANCE BY INGESTION OF MATERIAL THROUGH THE AIR RETURN SYSTEM OF THE AIRCRAFT. INSPECTION OF THE VENT RETURN SYSTEM SCREEN ASSY.