What was found
CREW REPORTED SMOKE TOILET CAS MESSAGE AT 6,000 FEET, WITH VISIBLE SMOKE IN MIDDLE PART OF CABIN. CREW LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE INSPECTED AIRCRAFT LIGHTING SYSTEM AND FOUND NO EVIDENCE OF BURNT SMELL IN CABIN. MAINTENANCE OPERATED AIR CONDITIONING PACKS WITH APU AND ENGINE AIR AND COULD NOT FIND ANY DEFECTS WITH SYSTEM. NO SMOKE OR BURN SMELL NOTED. MAINTENANCE PERFORMED CHECKS USING AIRCRAFT MAINTENANCE MANUAL. AIRCRAFT RELEASED FOR SERVICE.