As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHILE ON THE GROUND, ACFT FILLED WITH SMOKE WHEN APU BLEED WAS SELECTED ON. SMOKE APPEARED TO COME THROUGH ENVIRONMENTAL SYSTEM. FOUND APU OIL OVER SERVICED. SERVICED TO PROPER LEVEL IAW MM 12-11-03. CLEANED WATER SEPARATOR AND SOCK MM 21-50-00. REMOVED AND CLEANED APU GEAR BOX VENT TUBE MM 49-20-00. REINSTALLED TUBE. RAN APU WITH BLEED AIR ON FOR 1 HR WITH NO DEFECTS NOTED.