As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DEN - FLT 1634 - EN ROUTE DEN-ORD, AFTER DEPARTURE SMOKE IN CABIN. RETURNED TO DEN AND LANDED WITHOUT INCIDENT. TIGHTEND APU OIL LINE FITTING ELBOW. REPLACED LEFT AND RIHT COALESCER BAGS PRIOR TO PACK BURNOUT. ACCOMPLISHED PACK BURNOUT OF LEFT AND RIGHT PACKS PER MAINTENANCE MANUAL. SYSTEM GROUND CHECKED NORMAL OPERATION. (M)