A B727 in climb at FL230 made an emergency descent and diverted due to inability to control the cabi...

Attributes
ACN	393256
Time
Date	199802
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : orl
State Reference	FL
Altitude	msl bound lower : 23000 msl bound upper : 23000
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zma
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Flight Phase	climbout : intermediate altitude other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : second officer
Qualification	pilot : flight engineer
Experience	flight time last 90 days : 200 flight time total : 1050 flight time type : 600
ASRS Report	393256
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency other
Consequence	Other
Supplementary
Primary Problem	Aircraft

Narrative:

Out of fll while on climb out, when attempting to adjust cabin temperature, I noticed that the left mix valve was stuck in the full cold position, the right mix valve was working normally and I positioned it to the mid position. I advised the captain of the situation and proceeded to troubleshoot the problem, ie, determining if it's a failure of the mix valve position indictor or a failure of the mix valve itself. I determined it was a failure of the mix valve by observing no temperature increase while the selector was held in the warm position. Selected automatic on the selector and the mix valve was still stuck on full cold -- to no avail. At this time, I'm looking for the emergency/abnormal procedure in my aom when the cabin altitude warning horn went off. The only indication we had that there was a problem was the cabin altitude warning horn, for the cabin had climbed at a comfortable rate. At the time of the horn, the cabin had climbed to 10000 ft at FL220. The outflow valve was fully closed. Captain requested leveloff to ATC. When the cabin reached 10500 ft, I advised the captain that I cannot control the cabin. We accomplished the rapid depressurization and the emergency descent checklists. Captain got clearance and we descended to 14000 ft in less than 2 mins. At its highest, the cabin ascended to 12000 ft while the aircraft was on descent. Purser was notified by captain of the situation and we diverted to mia.

Original NASA ASRS Text

Title: A B727 IN CLB AT FL230 MADE AN EMER DSCNT AND DIVERTED DUE TO INABILITY TO CTL THE CABIN PRESSURIZATION CAUSED BY A FAILED L PACK MIXING VALVE.

Narrative: OUT OF FLL WHILE ON CLBOUT, WHEN ATTEMPTING TO ADJUST CABIN TEMP, I NOTICED THAT THE L MIX VALVE WAS STUCK IN THE FULL COLD POS, THE R MIX VALVE WAS WORKING NORMALLY AND I POSITIONED IT TO THE MID POS. I ADVISED THE CAPT OF THE SIT AND PROCEEDED TO TROUBLESHOOT THE PROB, IE, DETERMINING IF IT'S A FAILURE OF THE MIX VALVE POS INDICTOR OR A FAILURE OF THE MIX VALVE ITSELF. I DETERMINED IT WAS A FAILURE OF THE MIX VALVE BY OBSERVING NO TEMP INCREASE WHILE THE SELECTOR WAS HELD IN THE WARM POS. SELECTED AUTO ON THE SELECTOR AND THE MIX VALVE WAS STILL STUCK ON FULL COLD -- TO NO AVAIL. AT THIS TIME, I'M LOOKING FOR THE EMER/ABNORMAL PROC IN MY AOM WHEN THE CABIN ALT WARNING HORN WENT OFF. THE ONLY INDICATION WE HAD THAT THERE WAS A PROB WAS THE CABIN ALT WARNING HORN, FOR THE CABIN HAD CLBED AT A COMFORTABLE RATE. AT THE TIME OF THE HORN, THE CABIN HAD CLBED TO 10000 FT AT FL220. THE OUTFLOW VALVE WAS FULLY CLOSED. CAPT REQUESTED LEVELOFF TO ATC. WHEN THE CABIN REACHED 10500 FT, I ADVISED THE CAPT THAT I CANNOT CTL THE CABIN. WE ACCOMPLISHED THE RAPID DEPRESSURIZATION AND THE EMER DSCNT CHKLISTS. CAPT GOT CLRNC AND WE DSNDED TO 14000 FT IN LESS THAN 2 MINS. AT ITS HIGHEST, THE CABIN ASCENDED TO 12000 FT WHILE THE ACFT WAS ON DSCNT. PURSER WAS NOTIFIED BY CAPT OF THE SIT AND WE DIVERTED TO MIA.

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 B727 in climb at FL230 made an emergency descent and diverted due to inability to control the cabin pressurization caused by a failed left pack mixing valve.