Citation X (C750)
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition; General Declared Emergency
Aircraft
We were in the descent for landing passing through about 15;000 FT when the HYD VOL LOW A EICAS message illuminated. We checked the hydraulic page and it showed 16%. We ran the appropriate checklist and advised Approach that we would need delay vectors; for time to finish running the checklist; and that we would be declaring an emergency. [The] Captain had talked to our passengers of the situation and said they were comfortable and at ease. After checklist was complete we advised Approach that we were ready for vectors to final. The landing was normal. We stopped aircraft on the runway and shut the engines down; leaving APU power on. We chocked the aircraft with chocks borrowed from the fire truck. FBO arrived with a van and we got our passengers loaded and on their way safely. [FBO] hooked aircraft to the tug and towed us to the ramp where we continued talks with the company; completed paperwork and secured the aircraft for the night.
We stopped on the runway using the Emergency Brake System. Fire and rescue was plane side in case they were needed. The aircraft was moved by tug to [FBO] ramp. Post flight the crew found fresh HYD fluid on the belly of the aircraft as well as leaking from two wicks located on the aircraft's right side fuselage above the nose wheel marked as Emergency Pneumatic Brake and Gear Relief vents. All tires appear to have fluid on them.
CE-750 flight crew reported loss of Hydraulic System A on descent. Crew ran the checklists; declared an emergency; and landed safely; coming to a stop with the emergency brake system.