As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT CREW PERSONNEL REPORTED AFTER TAKEOFF COULD SMELL BURNING DUST SMELL. FOLLOWED BY BOTH AFT LAV SMOKE DETECTORS GOING OFF, RETURNED TO THE FIELD. MAINTENANCE DEPARTMENT PERSONNEL PERFORMED PACK BURNOUT IAW AMM 21-20-02, REMOVED AND REPLACED COALESCER BAGS NO SMOKE NOTED. AIRCRAFT RETURNED TO SERVICE.