What was found
ON FLIGHT 9800 THE CREW REPORTED, RECEIVED A SLAT FAIL CAUTION MESSAGE. THE SLATS FAILED TO OPEN. THE CREW FOLLOWED AIRCRAFT OPERATING MANUAL PROCEDURES AND THE CAPTAIN DECLARED AN EMERGENCY. THE AIRCRAFT LANDED WITHOUT INCIDENT. HAD A ZERO SLAT LANDING. THE AIRCRAFT WAS REMOVED FROM SERVICE. INSPECTED AND FOUND THE LEFT SLAT ACTUATOR TRIP INDICATOR WOULD NOT RESET AT TRACK 1-1. REMOVED AND REPLACED THE SLAT ACTUATOR AT TRACK 1-1 IAW CRJ-MM 27-81-09. THE OPERATIONAL CHECK OF THE FLAPS AND SLAT SYSTEM WERE GOOD. REFERENCE NON ROUTINE WORK CARDS 504-ORD-00216, 504-ORD-00217, AND 504-ORD-00218. THE AIRCRAFT WAS RETURNED TO SERVICE.