As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IMMEDIATELY AFTER TAKE OFF THE CABIN FILLED WITH NOTICEABLE AMOUNT OF SMOKE. DISSIPATED AFTER 3-5 MINUTES. RETURNED AND LANDED WITHOUT INCIDENT. REPLACED LIGHT AND RIGHT AIR CONDITIONING PRESSURE REGULATOR VALVES. BOTH COALESCERS BAGS, AND LEAKING APU MAGNETIC DRAIN PLUG. ACCOMPLISHED PACK BURNOUT. NO SMOKE OR ODOR NOTED. SYSTEM GROUND CHECKED NORMAL OPERATION.