As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT CREW REPORTED THAT SHORTLY AFTER TAKE OFF WITH THE APU RUNNING AND APU BLEED AIR SELECTED ON SMOKE ENTERED THE CABIN. THE APU BLEED AIR WAS SELECTED OFF AND THE SMOKE CLEARED. THE PILOT RETURNED TO THE DEPARTURE AIRPORT. TROUBLESHOOTING REVEALED THE SOURCE OF THE SMOKE WAS THE APU, WHEN RUNNING ONLY THE ENGINES AND ENGINE BLEED AIR NO SMOKE WAS EVIDENT. THE APU WAS DEFERRED IN ACCORDANCE WITH THE CORPORATE AIR, LLC MEL.