What was found
ON FINAL, A "HYDRAULIC VOLUME LOW" AMBER CAS MESSAGE ILLUMINATED AFTER LANDING GEAR WAS EXTENDED. A GO-AROUND WAS INITIATED AND THE APPROPRIATE CHECKLIST WAS ACCOMPLISHED. THE FLIGHT WAS THEN DIVERTED, AN EMERGENCY DECLARED AND THE ACFT WAS STOPPED ON THE RUNWAY, USING THE EMERGENCY BRAKE SYSTEM. DISCREPANCY WAS TROUBLESHOT TO A FAULTY RT WING ROLL SPOILER HYD PRESSURE LINE. PRESSURE LINE WAS REPLACED, ENGINE AND APU FUEL FILTERS REPLACED DUE TO HYDRAULIC PRESSURE LINE LOCATION INSIDE FUEL TANK. HYD SYSTEM WAS BLED, ENGINE AND APU RUNS WERE PERFORMED. ALL SYSTEMS LEAKS AND OPS CHECKS WERE GOOD. ACFT WAS RETURNED TO SERVICE.