As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED THAT WITH THE APU RUNNING AND THE APU BLEED AIR SELECTED ON ON SMOKE ENTERED CABIN. INITIAL FINDING DETERMINED THAT A COMPRESSOR CARBON SEAL FAILED AND ALLOWED ENGINE OIL TO ENTER THE BLEED AIR SYSTEM. THE APU WAS REMOVED FROM THE AIRCRAFT FOR REPAIRS.