What was found
IN LEVEL FLIGHT AT FL400, HYD VOLUME LOW A CAS MESSAGE CAME ON. OBSERVED THE VOLUME AT 14 PERCENT AND THE PRESSURE AT 2800 PSI. RAN THE CHECKLIST AND MADE A LANDING. THE EMERGENCY GEAR BLOW DOWN AND BRAKES WERE APPLIED. TROUBLESHOT TO BLOWN O-RING ON -A- SIDE PRESSURE TRANSDUCER. REPLACED O-RING WITH NEW. SERVICED HYDRAULIC SYSTEM & BLED BRAKES. ALL WORK DONE IAW CE750 M/M CHAP 29-10-09, AND 32-42-00. SYSTEM LEAK CHECK GOOD.