Citation 525CJ flight crew has pressurization problems; declares emergency and descends.

Attributes
ACN	723073
Time
Date	200701
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	msl single value : 35000
Environment
Flight Conditions	IMC
Weather Elements	Ice
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zzz.artcc
Operator	general aviation : corporate
Make Model Name	Citationjet C525/C526
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : atp
Experience	flight time last 90 days : 90 flight time total : 22300 flight time type : 300
ASRS Report	723073
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : commercial pilot : multi engine
Experience	flight time last 90 days : 90 flight time total : 1200 flight time type : 150
ASRS Report	723074
Events
Anomaly	aircraft equipment problem : critical inflight encounter : weather
Independent Detector	aircraft equipment other aircraft equipment : cabin climb rate other flight crewa other flight crewb
Resolutory Action	aircraft : equipment problem dissipated flight crew : declared emergency
Consequence	other
Supplementary
Problem Areas	Weather Aircraft
Primary Problem	Aircraft

Narrative:

Flight to ZZZ conducted under IFR at FL410. Initial descent clearance from center instructed us to descend to FL350. Gradual descent initiated. Subsequent clearance from center was to descend to FL240 and to expedite descent through FL320. Power was reduced further with engine anti-ice on. At approximately FL350 the 'door seal' annunciator light illuminated; a rushing noise was noticed; and the cabin rate of climb indicator showed the cabin climbing at 800 FPM. I declared an emergency and requested an immediate descent to 11000 ft. Throttles were further reduced; speed brakes deployed; and procedures for an emergency descent due to loss of pressurization were initiated. ATC gave us a further descent to FL240 and a 20 degree right turn (I am assuming for traffic). Cabin continued to climb at 800 FPM. At approximately 28000 ft; we added power to see if we could arrest the cabin climb with greater bleed airflow; and at approximately 25000 ft; the cabin rate of climb was reduced to zero. As the aircraft was descended towards 11000 ft; the cabin began to re-pressurize. The maximum cabin altitude reached was 13000 ft. At approximately 15000 ft; the 'door seal' annunciator extinguished and the pressurization system performed normally for the duration of the flight.

Original NASA ASRS Text

Title: CITATION 525CJ FLT CREW HAS PRESSURIZATION PROBS; DECLARES EMER AND DSNDS.

Narrative: FLT TO ZZZ CONDUCTED UNDER IFR AT FL410. INITIAL DSCNT CLRNC FROM CTR INSTRUCTED US TO DSND TO FL350. GRADUAL DSCNT INITIATED. SUBSEQUENT CLRNC FROM CTR WAS TO DSND TO FL240 AND TO EXPEDITE DSCNT THROUGH FL320. PWR WAS REDUCED FURTHER WITH ENG ANTI-ICE ON. AT APPROX FL350 THE 'DOOR SEAL' ANNUNCIATOR LIGHT ILLUMINATED; A RUSHING NOISE WAS NOTICED; AND THE CABIN RATE OF CLB INDICATOR SHOWED THE CABIN CLBING AT 800 FPM. I DECLARED AN EMER AND REQUESTED AN IMMEDIATE DSCNT TO 11000 FT. THROTTLES WERE FURTHER REDUCED; SPD BRAKES DEPLOYED; AND PROCS FOR AN EMER DSCNT DUE TO LOSS OF PRESSURIZATION WERE INITIATED. ATC GAVE US A FURTHER DSCNT TO FL240 AND A 20 DEG R TURN (I AM ASSUMING FOR TFC). CABIN CONTINUED TO CLB AT 800 FPM. AT APPROX 28000 FT; WE ADDED PWR TO SEE IF WE COULD ARREST THE CABIN CLB WITH GREATER BLEED AIRFLOW; AND AT APPROX 25000 FT; THE CABIN RATE OF CLB WAS REDUCED TO ZERO. AS THE ACFT WAS DSNDED TOWARDS 11000 FT; THE CABIN BEGAN TO RE-PRESSURIZE. THE MAX CABIN ALT REACHED WAS 13000 FT. AT APPROX 15000 FT; THE 'DOOR SEAL' ANNUNCIATOR EXTINGUISHED AND THE PRESSURIZATION SYS PERFORMED NORMALLY FOR THE DURATION OF THE FLT.

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.