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Loss of cabin pressurization in air carrier aircraft causes flight crew to descend from FL230 to 10000 ft MSL.
| Attributes | |
| ACN | 434690 |
| Time | |
| Date | 199904 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | navaid : jvl.ndb |
| Altitude | msl bound lower : 10000 msl bound upper : 23000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zau.artcc tower : vcv.tower |
| Operator | common carrier : air carrier |
| Make Model Name | B727 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other ndb |
| Flight Phase | climbout : vacating altitude |
| Route In Use | enroute : on vectors |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : second officer |
| Qualification | pilot : flight engineer pilot : atp |
| Experience | flight time last 90 days : 300 flight time total : 3300 flight time type : 190 |
| ASRS Report | 434690 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : flight engineer pilot : instrument pilot : multi engine pilot : atp pilot : cfi pilot : commercial |
| Experience | flight time last 90 days : 180 flight time total : 9000 flight time type : 4000 |
| ASRS Report | 434689 |
| Events | |
| Anomaly | aircraft equipment problem : less severe other anomaly other |
| Independent Detector | other flight crewa other flight crewb other other : flt crew 3 |
| Resolutory Action | flight crew : overcame equipment problem |
| Consequence | other |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance Airport |
| Primary Problem | Flight Crew Human Performance |
Narrative:
During climb at FL230 1 beep was heard from a warning horn. A rapid scan of the cockpit did not reveal any warning lights on. About 5 seconds later the cabin altitude warning horn came on steadily. Cabin altimeter was at 10000 ft with a 3 psi differential and a 500-700 FPM climb. Cargo heat outflow valve was closed, ATC advised and a rapid descent was initiated toward 10000 ft while continuing to evaluate. Recycled pack switches and found that the right pack had not been providing any pressure. After recycling, the cabin immediately began to repressurize. Maximum cabin altitude was about 10500 ft for less than 1 min. Descent was continued to 10000 ft because we were not sure what had caused the problem. Level at 10000 ft, we cycled each pack off individually and found that the right pack held cabin pressure fine, but the left pack could not. Dispatch and maintenance were contacted and advised of situation. Write-ups were entered in the logbook for loss of cabin pressure, use of the oxygen bottle and results of troubleshooting the pack system.
Original NASA ASRS Text
Title: LOSS OF CABIN PRESSURIZATION IN ACR ACFT CAUSES FLC TO DSND FROM FL230 TO 10000 FT MSL.
Narrative: DURING CLB AT FL230 1 BEEP WAS HEARD FROM A WARNING HORN. A RAPID SCAN OF THE COCKPIT DID NOT REVEAL ANY WARNING LIGHTS ON. ABOUT 5 SECONDS LATER THE CABIN ALT WARNING HORN CAME ON STEADILY. CABIN ALTIMETER WAS AT 10000 FT WITH A 3 PSI DIFFERENTIAL AND A 500-700 FPM CLB. CARGO HEAT OUTFLOW VALVE WAS CLOSED, ATC ADVISED AND A RAPID DSCNT WAS INITIATED TOWARD 10000 FT WHILE CONTINUING TO EVALUATE. RECYCLED PACK SWITCHES AND FOUND THAT THE R PACK HAD NOT BEEN PROVIDING ANY PRESSURE. AFTER RECYCLING, THE CABIN IMMEDIATELY BEGAN TO REPRESSURIZE. MAX CABIN ALT WAS ABOUT 10500 FT FOR LESS THAN 1 MIN. DSCNT WAS CONTINUED TO 10000 FT BECAUSE WE WERE NOT SURE WHAT HAD CAUSED THE PROB. LEVEL AT 10000 FT, WE CYCLED EACH PACK OFF INDIVIDUALLY AND FOUND THAT THE R PACK HELD CABIN PRESSURE FINE, BUT THE L PACK COULD NOT. DISPATCH AND MAINT WERE CONTACTED AND ADVISED OF SIT. WRITE-UPS WERE ENTERED IN THE LOGBOOK FOR LOSS OF CABIN PRESSURE, USE OF THE OXYGEN BOTTLE AND RESULTS OF TROUBLESHOOTING THE PACK SYS.
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.