C550 CREW LOST CABIN PRESSURIZATION TWICE AFTER ADJUSTING THE PACK TEMP CTL. THE ACFT ONLY HAS A SINGLE PACK. WHEN IT TRIPS OFF THE ACFT HAS NO PRESSURIZATION SOURCE.

Narrative

WE DEPARTED DESTIN; FL (DTS) FOR PONTIAC; MI (PTK). AS WE WERE CLBING THROUGH FL275 WE STARTED LOSING PRESSURIZATION AFTER ADJUSTING THE TEMP CTL LEVER. WE STOPPED OUR CLB AT FL280 AND REFERRED TO THE EMER CHKLIST. DESPITE USING CHKLIST PROCS WE WERE UNABLE TO CTL CABIN PRESSURE. AS A RESULT WE REQUESTED AND BEGAN OUR DSCNT TO 10000 FT. THE FO WAS FLYING AND THE CAPT WAS DOING CHKLISTS; RADIOS AND ASSUMING PAX SAFETY. WE RECEIVED VECTORS FOR A VISUAL APCH AND LNDG AT MGM. ON THE GND; THE FBO MAINT; IN ACCORDANCE WITH OUR COMPANY'S MAINT DEPT; INSPECTED FOR THE OVERWT LNDG; SVCED THE OXYGEN; INSPECTED AND REPACKED THE PAX OXYGEN MASKS AND INSPECTED AND SVCED THE PRESSURIZATION. GND PRESSURIZATION CHKS WERE COMPLETED AND MAINT RETURNED THE ACFT TO SVC IN AN AIRWORTHY CONDITION. WE DEPARTED MGM FOR PTK. WE LEVELED OFF AT A CRUISE ALT OF FL290. PRESSURIZATION WAS HOLDING WELL UNTIL THE CABIN TEMP KNOB WAS ADJUSTED TO A WARMER SETTING. IMMEDIATELY; THE CABIN BEGAN TO DEPRESSURIZE. WE WENT THROUGH THE EMER CHKLIST; BUT WERE STILL UNABLE TO CTL CABIN PRESSURE. AS A RESULT WE REQUESTED AND BEGAN OUR DSCNT TO 10000 FT. THE CAPT WAS FLYING AND THE FO DID CHKLISTS; RADIOS AND ASSURED PAX SAFETY. AT 10000 FT WE NOTICED OUR PRESSURIZATION HAD BEEN RESTORED. WE DISCUSSED THE OPTION OF CONTINUING THE FLT TO PTK NOTING FUEL AND OXYGEN REQUIREMENTS. WE AGREED THAT THE FLT COULD CONTINUE SAFELY AT 10000 FT AND DISCUSSED IT WITH OUR PAX. AS THE FLT CONTINUED; WE MAINTAINED NORMAL PRESSURIZATION AND AGREED TO CLB TO 14000 FT TO GET A BETTER FUEL BURN. THE PRESSURIZATION REMAINED NORMAL FOR THE REMAINDER OF THE FLT. THE CREW MAINTAINED PROPER COORD AND COM THROUGHOUT THE ENTIRE TRIP. ATC RESPONDED TO US EFFICIENTLY AND THEY WERE ATTENTIVE TO ALL REQUESTS.