As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EN ROUTE, DAY-ORD UNKNOWN SMOKE IN CABIN AND IN COCKPIT DURING TAKEOFF. DISSIPATED AFTER APPROXIMATELY 5 MINUTES. RETURNED AND LANDED WITHOUT INCIDENT. AIRCRAFT WAS INSPECTED AND FOUND TO BE IN SAFE CONDITION FOR FERRY FLIGHT FROM DAY TO ORD. REPLACED BOTH COALESCER BAGS AND ACCOMPLISHED PACK BURN OUT. SYSTEM GROUND CHECKED NORMAL OPERATION.