What was found
ON CLIMB OUT FROM KLAS PASSING 10,000FT WE GOT AN AMBER EMERGENCY EXIT CAS MSG. LEVELED OFF AT 12,000FT & RAN THE QRH CHECKLIST. IT WAS NOTED THAT AT SPEEDS ABOVE 300KTS A DISTINCT VIBRATION WAS FELT IN THE CONTROL COLUMN AS WELL AS THE FUSELAGE. SLOWED TO 290KTS AND THE VIBRATION WENT AWAY. REMOVED RT HEAT EXCHANGER BYPASS VALVE AND REPLACED WITH CUSTOMER SUPPLIED NEW VALVE. PERFORMED SYSTEM LEAK, BLEED AND OPERATIONAL CHECK, NO DEFECTS NOTED. SERVICED HYDRAULIC TO FULL. RAN ENGINES AND CYCLE FLIGHT CONTROLS AND RT TEMP REACH AROUND 52. WORK PERFORMED IAW AMM 29-12-45.