A cessna citation 560 flight crew executed an emergency descent after loss of cabin pressure near sd...

Attributes
ACN	441387
Time
Date	199906
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : iiu.vortac
State Reference	KY
Altitude	msl bound lower : 11000 msl bound upper : 41000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid.artcc
Operator	general aviation : corporate
Make Model Name	Citation V
Operating Under FAR Part	Part 91
Navigation In Use	other other vortac
Flight Phase	cruise : level cruise : enroute altitude change
Route In Use	enroute airway : ns.airway
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 90 flight time total : 3500 flight time type : 500
ASRS Report	441387
Person 2
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 100 flight time total : 5000 flight time type : 2500
ASRS Report	441397
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	controller : issued new clearance flight crew : declared emergency flight crew : took evasive action
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

In cruise flight at FL410, the cabin door seal annunciator illuminated. We requested and received a descent clearance to FL350. Again we requested lower prior to reaching FL350 and received a clearance to FL250. We did not inform ATC of our annunciator light. In the descent at approximately FL350-FL370 the cabin pressurization began climbing rapidly along with the sound of air rushing around the door. At this time the crew and passenger donned the oxygen masks and notified ATC that we were executing an emergency descent. The cabin pressurization climbed to approximately 15000 ft. ATC cleared us to 11000 ft with no further incident and we continued to our destination. The maintenance department found excessive moisture in the bleed air line supplying the door seal. This moisture froze and blocked the supply line causing the cabin to depressurize.

Original NASA ASRS Text

Title: A CESSNA CITATION 560 FLC EXECUTED AN EMER DSCNT AFTER LOSS OF CABIN PRESSURE NEAR SDF.

Narrative: IN CRUISE FLT AT FL410, THE CABIN DOOR SEAL ANNUNCIATOR ILLUMINATED. WE REQUESTED AND RECEIVED A DSCNT CLRNC TO FL350. AGAIN WE REQUESTED LOWER PRIOR TO REACHING FL350 AND RECEIVED A CLRNC TO FL250. WE DID NOT INFORM ATC OF OUR ANNUNCIATOR LIGHT. IN THE DSCNT AT APPROX FL350-FL370 THE CABIN PRESSURIZATION BEGAN CLBING RAPIDLY ALONG WITH THE SOUND OF AIR RUSHING AROUND THE DOOR. AT THIS TIME THE CREW AND PAX DONNED THE OXYGEN MASKS AND NOTIFIED ATC THAT WE WERE EXECUTING AN EMER DSCNT. THE CABIN PRESSURIZATION CLBED TO APPROX 15000 FT. ATC CLRED US TO 11000 FT WITH NO FURTHER INCIDENT AND WE CONTINUED TO OUR DEST. THE MAINT DEPT FOUND EXCESSIVE MOISTURE IN THE BLEED AIR LINE SUPPLYING THE DOOR SEAL. THIS MOISTURE FROZE AND BLOCKED THE SUPPLY LINE CAUSING THE CABIN TO DEPRESSURIZE.

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.

A cessna citation 560 flight crew executed an emergency descent after loss of cabin pressure near sdf.