As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ORD INFLIGHT T1502/01NOV - WHITE SMOKE REPORTED IN CABIN WITH OIL ODOR. RETURNED TO ORD AND LANDED WITHOUT INCIDENT. REPLACED AUXILLIARY POWER UNIT (APU) DUE TO INGESTION OF OIL FROM LEAK. ACCOMPLISHED PNEUMATIC DUCT BURNOUT. SYSTEM GROUND CHECKED NORMAL OPERATION.