What was found
THE CREW REPORTED THAT THE AFT RIGHT LAV (LAV M) SMOKE DETECTOR WENT OFF WHILE ON APPROACH TO EWR. THERE WAS VISIBLE SMOKE WITH AN ELECTRICAL SMELL IN THE AFT LAV AREA. THE AFT LAVS WERE OPENED AND THE TRASH CONTAINERS WERE INSPECTED WITH NO EVIDENCE OF FIRE IN EITHER OF THE AFT LAVS. THE AIRCRAFT LANDED AT EWR WITHOUT INCIDENT. AN INITIAL INSPECTION OF THE LIGHTS AND CEILING AREA FOUND NO EVIDENCE OF BURNED WIRES. MAINTENANCE FOUND THE R-4 DOOR HEATER BAD. THE DOOR HEATER WAS REPLACED IAW MM 21-45-06, PAGE 401. OPERATIONAL CHECKS WERE GOOD.