Narrative:

Cruising at FL370 a change in pressurization was noted by ear. Checking cabin altitude gauge, cabin rate pegged at 2000 FPM climb. ATC was advised and lower altitude was requested pending cockpit investigation for cause. FL350 was assigned and descent to such was accomplished. As cockpit investigation revealed no solution to the problem, an emergency was declared with ATC. At FL350 we may have deviated 200- 250 ft below assigned altitude trying to control pressurization leak. ATC assigned 13000 ft and an emergency descent as per checklist was conducted. Pilots were on oxygen and passenger masks were deployed automatically as cabin climbed past 10000 ft in descent. No injuries were incurred. In my opinion, both crew and passenger handled emergency above and beyond normal expectations. All remained calm and collected throughout a difficult situation. Cause of pressurization failure was ecu ducting detachment thereby allowing loss of cabin pressure venting out in tail cone. Hopefully this incident will reinstill the importance of check and doublechk to maintenance relating to how serious oversights can be. Even though I believe that we did not deviation from our assigned altitude in ATC eyes, hindsight would suggest using the autoplt when troubleshooting a problem. With regard to possible traffic conflict on descent, I know there were no RA's on the TCASII, but that is only a 6 mi circle and ATC may have deviated other aircraft. If so, I am unaware. I do feel our annual simulator training proved very useful in dealing with this emergency.

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Original NASA ASRS Text

Title: FLC OF CPR LTT HAS PRESSURIZATION FAILURE. EMER DSCNT ACCOMPLISHED.

Narrative: CRUISING AT FL370 A CHANGE IN PRESSURIZATION WAS NOTED BY EAR. CHKING CABIN ALT GAUGE, CABIN RATE PEGGED AT 2000 FPM CLB. ATC WAS ADVISED AND LOWER ALT WAS REQUESTED PENDING COCKPIT INVESTIGATION FOR CAUSE. FL350 WAS ASSIGNED AND DSCNT TO SUCH WAS ACCOMPLISHED. AS COCKPIT INVESTIGATION REVEALED NO SOLUTION TO THE PROB, AN EMER WAS DECLARED WITH ATC. AT FL350 WE MAY HAVE DEVIATED 200- 250 FT BELOW ASSIGNED ALT TRYING TO CTL PRESSURIZATION LEAK. ATC ASSIGNED 13000 FT AND AN EMER DSCNT AS PER CHKLIST WAS CONDUCTED. PLTS WERE ON OXYGEN AND PAX MASKS WERE DEPLOYED AUTOMATICALLY AS CABIN CLBED PAST 10000 FT IN DSCNT. NO INJURIES WERE INCURRED. IN MY OPINION, BOTH CREW AND PAX HANDLED EMER ABOVE AND BEYOND NORMAL EXPECTATIONS. ALL REMAINED CALM AND COLLECTED THROUGHOUT A DIFFICULT SIT. CAUSE OF PRESSURIZATION FAILURE WAS ECU DUCTING DETACHMENT THEREBY ALLOWING LOSS OF CABIN PRESSURE VENTING OUT IN TAIL CONE. HOPEFULLY THIS INCIDENT WILL REINSTILL THE IMPORTANCE OF CHK AND DOUBLECHK TO MAINT RELATING TO HOW SERIOUS OVERSIGHTS CAN BE. EVEN THOUGH I BELIEVE THAT WE DID NOT DEV FROM OUR ASSIGNED ALT IN ATC EYES, HINDSIGHT WOULD SUGGEST USING THE AUTOPLT WHEN TROUBLESHOOTING A PROB. WITH REGARD TO POSSIBLE TFC CONFLICT ON DSCNT, I KNOW THERE WERE NO RA'S ON THE TCASII, BUT THAT IS ONLY A 6 MI CIRCLE AND ATC MAY HAVE DEVIATED OTHER ACFT. IF SO, I AM UNAWARE. I DO FEEL OUR ANNUAL SIMULATOR TRAINING PROVED VERY USEFUL IN DEALING WITH THIS EMER.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.