As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAX - FLT 1234 - AFTER TAKEOFF LAX, SMOKE NOTED IN CABIN. AIRCRAFT RETURNED TO LAX AND LANDED WITHOUT INCIDENT. REPLACED APU OIL COOLER O-RINGS AND ALL COALESCER BAGS. ACCOMPLISHED LEAK CHECK AND PACK BURNOUT PROCEDURE WITH NO SMOKE NOTED. SYSTEM GROUND CHECKED NORMAL OPERATIONS. (M)