|37000 Feet||Browse and search NASA's
Aviation Safety Reporting System
|Local Time Of Day||1201 To 1800|
|Locale Reference||atc facility : orl|
|Altitude||msl bound lower : 23000|
msl bound upper : 23000
|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|
|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
|Affiliation||company : air carrier|
|Function||flight crew : captain|
oversight : pic
|Qualification||pilot : atp|
|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|
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.