As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
5 HRS INTO FLIGHT THE SMOKE DETECTOR IN LAV 4LC WENT OFF WITH NO INDICATION ON FLIGHT DECK. FAS RESPONDED AND FOUND NO SMELL ON ANY INDICATION OF FIRE OR SMOKE. FUNCTIONED NORMALLY. PERFORMED LAVATORY SMOKE DETECTION SELF TEST IAW AMM 26-13-00-740-801, LAV 4LC TEST OK. THE AIRCRAFT WAS NOT GROUNDED.