As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT RETURNED TO FIELD WITH BOTH SMOKE DETECTORS IN THE LAVS GOING OFF. CREW NOTED THAT THE APU WAS OFF ON TAKEOFF AND CLIMB. PURGED BLEED AIR DUCTS AND CHANGED WATER SEPARATOR FILTER SOCKS. GROUND RAN AIRCRAFT, OPERATIONAL CHECK GOOD. NO SMOKE NOTED. AIRCRAFT TEST FLIGHT SATISFACTORY.