What was found
IAH- WHILE PERFORMING A LINE CHECK INSPECTION THE MECHANIC NOTED THAT THE EMERGENCY LIGHTINGDID NOT ILLUMINATE DURING TESTING. IAH- MAINTENANCE REMOVED AND REPLACED THE (15 WL POSITION)EMERGENCY BATTERY, PERFORMED A OPERATIONAL CHECK OF THE EMERGENCY LIGHTING SYSTEM, NO DEFECTS NOTED, AND, THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.