CL65 crew was unable to maintain cabin pressurization on 1 pack after the left pack failed.

Attributes
ACN	531604
Time
Date	200111
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : obk.vor
State Reference	FL
Altitude	msl bound lower : 10000 msl bound upper : 27000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	artcc : zau.artcc
Operator	common carrier : air carrier
Make Model Name	Regional Jet CL65, Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : cfi pilot : commercial
Experience	flight time last 90 days : 170 flight time total : 1750 flight time type : 240
ASRS Report	531604
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : critical
Resolutory Action	controller : issued new clearance controller : provided flight assist flight crew : declared emergency none taken : detected after the fact
Consequence	other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

While at cruise, we had a 'left pack high pressure' message. We could not maintain the cabin pressure and descended down to 10000 ft MSL and continued to destination. Event: while at cruise at FL270 we lost the left pack due to high pressure. Action: due to limitations, we descended to FL250. The captain ran the 'left pack high pressure' QRH and the problem was not solved. Event: cabin altitude was increasing at about 700 FPM and was currently at 4000 ft. Action: we decided to put our oxygen masks on just to be safe. We decided to descend and asked center for a lower altitude. Event: we then received 3 master cautions -- 'display cool,' 'air incorporated inoperative,' and 'cabin pressure.' while descending to FL190, we figured the cabin would not stabilized. Action: we then advised ATC we would need lower. We were cleared to 11000 ft. I asked for 10000 ft and was approved. I did an emergency descent to 10000 ft. Event: as all this was going on, the captain had run the QRH's for all 3 master cautions. In the descent to 10000 ft, the master warning for cabin altitude sounded. Action: the captain ran the QRH, talked with company maintenance, and we were advised to continue to cvg. We did continue at 1000 ft to cvg without further incident.

Original NASA ASRS Text

Title: CL65 CREW WAS UNABLE TO MAINTAIN CABIN PRESSURIZATION ON 1 PACK AFTER THE L PACK FAILED.

Narrative: WHILE AT CRUISE, WE HAD A 'L PACK HIGH PRESSURE' MESSAGE. WE COULD NOT MAINTAIN THE CABIN PRESSURE AND DSNDED DOWN TO 10000 FT MSL AND CONTINUED TO DEST. EVENT: WHILE AT CRUISE AT FL270 WE LOST THE L PACK DUE TO HIGH PRESSURE. ACTION: DUE TO LIMITATIONS, WE DSNDED TO FL250. THE CAPT RAN THE 'L PACK HIGH PRESSURE' QRH AND THE PROB WAS NOT SOLVED. EVENT: CABIN ALT WAS INCREASING AT ABOUT 700 FPM AND WAS CURRENTLY AT 4000 FT. ACTION: WE DECIDED TO PUT OUR OXYGEN MASKS ON JUST TO BE SAFE. WE DECIDED TO DSND AND ASKED CTR FOR A LOWER ALT. EVENT: WE THEN RECEIVED 3 MASTER CAUTIONS -- 'DISPLAY COOL,' 'AIR INC INOP,' AND 'CABIN PRESSURE.' WHILE DSNDING TO FL190, WE FIGURED THE CABIN WOULD NOT STABILIZED. ACTION: WE THEN ADVISED ATC WE WOULD NEED LOWER. WE WERE CLRED TO 11000 FT. I ASKED FOR 10000 FT AND WAS APPROVED. I DID AN EMER DSCNT TO 10000 FT. EVENT: AS ALL THIS WAS GOING ON, THE CAPT HAD RUN THE QRH'S FOR ALL 3 MASTER CAUTIONS. IN THE DSCNT TO 10000 FT, THE MASTER WARNING FOR CABIN ALT SOUNDED. ACTION: THE CAPT RAN THE QRH, TALKED WITH COMPANY MAINT, AND WE WERE ADVISED TO CONTINUE TO CVG. WE DID CONTINUE AT 1000 FT TO CVG WITHOUT FURTHER INCIDENT.

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.