What was found
DURING A ROUTINE OVERNIGHT SERVICE CHECK INSPECTION, MAINTENANCE REPORTED A PORTION OF THE EMERGENCY EVACUATION LIGHTING SYSTEM WOULD NOT TEST. MAINTENANCE REMOVED AND REPLACED THE APPROPRIATE BATTERIES IN THE POWER SUPPLY BATTERY PACK AND MADE ALL REQUIRED CORRECTIONS AND OPERATIONAL CHECK WAS ACCOMPLISHED PER AMM 33-50-00, SYSTEM OPERATIONAL CHECKED NORMAL. THE AIRCRAFT HAS BEEN RETURNED TO SERVICE.