Citation CE560 has pressurization problem; declares emergency and executes emergency descent.

Attributes
ACN	718822
Time
Date	200611
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zzz.artcc
State Reference	US
Altitude	msl single value : 41000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	common carrier : air carrier
Make Model Name	Citation V
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : cfi pilot : multi engine pilot : instrument pilot : commercial
Experience	flight time last 90 days : 100 flight time total : 22000 flight time type : 450
ASRS Report	718822
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : cfi pilot : commercial pilot : multi engine pilot : instrument
Experience	flight time last 90 days : 75 flight time total : 11000 flight time type : 2500
ASRS Report	718823
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : published procedure
Independent Detector	aircraft equipment other aircraft equipment : emer pressurization other flight crewa other flight crewb
Resolutory Action	flight crew : declared emergency flight crew : overcame equipment problem
Consequence	Other
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance

Narrative:

We were cruising at FL410. We had reached that altitude after departing about 20 mins earlier. Our emergency pressurization came on and our cabin was climbing. Earlier in the day we had a situation reported with a leaky pilot window. We donned our oxygen masks; advised ATC and began a descent to FL370. We worked through the problem on descent and found it was not a pressurization problem but we had shut down our acm (air cycle machine) by making the cabin temperature too cold. We warmed up the setting and all was well. Informed ATC and continued on our way at FL370.

Original NASA ASRS Text

Title: CITATION CE560 HAS PRESSURIZATION PROB; DECLARES EMER AND EXECUTES EMER DSCNT.

Narrative: WE WERE CRUISING AT FL410. WE HAD REACHED THAT ALT AFTER DEPARTING ABOUT 20 MINS EARLIER. OUR EMER PRESSURIZATION CAME ON AND OUR CABIN WAS CLBING. EARLIER IN THE DAY WE HAD A SITUATION RPTED WITH A LEAKY PLT WINDOW. WE DONNED OUR OXYGEN MASKS; ADVISED ATC AND BEGAN A DSCNT TO FL370. WE WORKED THROUGH THE PROB ON DSCNT AND FOUND IT WAS NOT A PRESSURIZATION PROB BUT WE HAD SHUT DOWN OUR ACM (AIR CYCLE MACHINE) BY MAKING THE CABIN TEMP TOO COLD. WE WARMED UP THE SETTING AND ALL WAS WELL. INFORMED ATC AND CONTINUED ON OUR WAY AT FL370.

Data retrieved from NASA's ASRS site as of January 2009 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.