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A DC9-30 starts losing cabin pressure at a slow rate. Crew finally declares an emergency after having started a controled descent. PIC says the passenger never noticed any problem.
| Attributes | |
| ACN | 371572 |
| Time | |
| Date | 199706 |
| Day | Sun |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : msp |
| State Reference | MN |
| Altitude | msl bound lower : 9000 msl bound upper : 35000 |
| Environment | |
| Flight Conditions | Mixed |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zmp |
| Operator | common carrier : air carrier |
| Make Model Name | DC-10 30 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | cruise other descent other other |
| Route In Use | enroute other |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 180 flight time total : 7000 flight time type : 2000 |
| ASRS Report | 371572 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Events | |
| Anomaly | aircraft equipment problem : critical other anomaly other |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | controller : issued new clearance flight crew : exited adverse environment flight crew : declared emergency other |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Aircraft |
Narrative:
At FL350 we noticed the cabin was climbing at 300-400 FPM and was around 9000 ft. We requested a descent and worked the problem. The manual controller had no affect on the outflow valve. It showed full closed and the cabin continued to climb. We now declared an emergency and the cabin pressurization light came on and the cabin went to 11000 ft. We leveled at 9000 ft. Masks did not drop, and the people never even noticed. Center was super good help. It was interesting that we happened to see this early and I believe that's why it was 'no big deal.' also believe the problem to be: 1) either a small leak, 2) controller problem, 3) sticky outflow valve. The procedure worked well, except communications between pilots is at best difficult with the old communication panel.
Original NASA ASRS Text
Title: A DC9-30 STARTS LOSING CABIN PRESSURE AT A SLOW RATE. CREW FINALLY DECLARES AN EMER AFTER HAVING STARTED A CTLED DSCNT. PIC SAYS THE PAX NEVER NOTICED ANY PROB.
Narrative: AT FL350 WE NOTICED THE CABIN WAS CLBING AT 300-400 FPM AND WAS AROUND 9000 FT. WE REQUESTED A DSCNT AND WORKED THE PROB. THE MANUAL CTLR HAD NO AFFECT ON THE OUTFLOW VALVE. IT SHOWED FULL CLOSED AND THE CABIN CONTINUED TO CLB. WE NOW DECLARED AN EMER AND THE CABIN PRESSURIZATION LIGHT CAME ON AND THE CABIN WENT TO 11000 FT. WE LEVELED AT 9000 FT. MASKS DID NOT DROP, AND THE PEOPLE NEVER EVEN NOTICED. CTR WAS SUPER GOOD HELP. IT WAS INTERESTING THAT WE HAPPENED TO SEE THIS EARLY AND I BELIEVE THAT'S WHY IT WAS 'NO BIG DEAL.' ALSO BELIEVE THE PROB TO BE: 1) EITHER A SMALL LEAK, 2) CTLR PROB, 3) STICKY OUTFLOW VALVE. THE PROC WORKED WELL, EXCEPT COMS BTWN PLTS IS AT BEST DIFFICULT WITH THE OLD COM PANEL.
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.