What was found
WHILE AT FL450, FLIGHT CREW RECEIVED A "RED" CABIN ALT WARNING HIGH CAS MESSAGE, ALONG WITH A MASTER CAUTION WARNING AND AURAL ALERT. THE CREW DONNED THEIR O2 MASKS; DEPLOYED THE PAX O2 MASKS AND IMMEDIATELY BEGAN AN EMERGENCY DESCENT. CREW INFORMED ATC THAT THEY WANTED TO DIVERT, AND WERE GIVEN DIRECT TO AIRPORT, WHERE THEY LANDED UNEVENTFULLY. A FERRY FLIGHT INSPECTION WAS ACCOMPLISHED AND THE ACFT WAS FLOWN FOR TROUBLESHOOTING. MAINTENANCE TECHS FOUND A FAILED RT SAFETY VALVE. SAFETY VALVE PN 81141A010303 WAS REPLACED WITH A REPAIRED UNIT. PRESSURIZATION, OPERATIONAL CHECKS WERE PERFORMED, WITH NO DEFECTS NOTED. A SUCCESSFUL MAINTENANCE CHECK FLIGHT WAS ACCOMPLISHED, AND THE ACFT WAS RETURNED TO SERVICE.