Citation I (C500)
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 85; Flight Crew Total 5200; Flight Crew Type 425
Human-Machine Interface; Situational Awareness
Aircraft Equipment Problem Critical
Air Traffic Control Issued New Clearance; Flight Crew Overcame Equipment Problem; General Declared Emergency
Aircraft; Human Factors
While at flight level 370 our Emergency pressurization came on. Thinking our cabin was depressurizing we put on our O2 masks and started a descent. We put 7700 in the transponder and once we were able to communicate with ATC they asked if we were doing an emergency descent. I confirmed and said we were having pressurization trouble. They cleared us to 10;000 FT and were very helpful. When we went through the checklist we found out that our ACM ejector failed due to overheating and that emergency pressure takes over to allow the ACM ejector to cool. We selected a warmer cabin setting and the system reset. No pressurization was lost. We continued our flight to destination.
CE500 Captain experiences Emergency pressurization coming on at FL370. Oxygen masks are donned; descent is initiated and 7700 is squawked before discovering that the ACM can be reset by selecting a warmer temperature.