As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAKEOFF, COCKPIT AND CABIN BEGAN FILLING WITH SMOKE. AN IMMEDIATE RETURN FOR LANDING WAS ACCOMPLISHED. FOUND APU OVER SERVICED AND REMOVED EXCESS OIL. INSPECTED ENGINE AND AIRFRAME. INSPECTED BOTH WATER SEPARATOR AND CLEANED. OPERATIONAL AND LEAK CHECKED GOOD. WORK DONE IAW AMM 21-11-00.