As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRBORNE RETURN FOR SMOKE/FUMES IN CABIN. FIRST OFFICERS AFT LAV SMOKE DETECTOR ACTIVATED. MTC IN WORK DOING DUCT BURNOUT AND WASHING APU INLET. REMOVED AND REPLACED COALESCER BAGS CLEANED RESIDUAL OIL FROM APU INLET PERFORM FULL DUCT BURNOUT PER OPN 5089. NO SMOKE OR ODORS. REMOVED AND REPLACED COALESCER BAGS.