As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR RETURN DUE TO SMELL OF BURNING AND SMOKE IN CABIN. DROPPED PSU'S AND CLEANED PANELS, NO ODORS OR EVIDENCE OF BURNING NOTED. REMOVED AND REPLACED COALESCER BAGS, REF AMM 21-20-02 RAN ENGINES REF AMM 71-00-00 OPS CHECK NORMAL. AIRCRAFT RETURNED TO SERVICE.