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Slow loss of cabin pressure in an MD80 forces the PIC to be creative in a power on, speed brake deployed, rapid descent to maintain a slower cabin pressure loss that started at FL330 over dbq, ia.
| Attributes | |
| ACN | 554597 |
| Time | |
| Date | 200207 |
| Day | Sun |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | airport : dbq.airport |
| State Reference | IA |
| Altitude | msl bound lower : 17000 msl bound upper : 33000 |
| Aircraft 1 | |
| Controlling Facilities | artcc : zau.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | MD-80 Super 80 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | cruise : level |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 554597 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Events | |
| Anomaly | aircraft equipment problem : critical other anomaly other |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | controller : issued new clearance other |
| Consequence | other other |
| Supplementary | |
| Problem Areas | Aircraft |
| Primary Problem | Aircraft |
Narrative:
Approaching dbq, FL330, pressure flow light came on. Followed operations manual procedure. No result. Cabin altitude 8000 ft. Climbing 200-300 FPM, requested lower, descended to FL290. Cabin altitude stabilized first then resumed climb. Requested 14000 ft. ATC approved. In initial descent, cabin altitude reached 9800 ft and red cabin altitude light on momentarily. Maintained 1.4 EPR with full speed brakes at barber pole to keep cabin altitude from climbing. This worked. Passing FL240, cabin altitude started slow descent 200 FPM. Asked ATC for 17000 ft. Resumed normal cruise confign at 17000 ft cabin altitude. Continued slow descent (200 FPM) as long as EPR above 1.5 to 1.7. Approaching ord, descent was normal as long as EPR stayed 1.4. By 5000 ft, cabin altitude at field elevation and remained so to normal descent and landing.
Original NASA ASRS Text
Title: SLOW LOSS OF CABIN PRESSURE IN AN MD80 FORCES THE PIC TO BE CREATIVE IN A PWR ON, SPD BRAKE DEPLOYED, RAPID DSCNT TO MAINTAIN A SLOWER CABIN PRESSURE LOSS THAT STARTED AT FL330 OVER DBQ, IA.
Narrative: APCHING DBQ, FL330, PRESSURE FLOW LIGHT CAME ON. FOLLOWED OPS MANUAL PROC. NO RESULT. CABIN ALT 8000 FT. CLBING 200-300 FPM, REQUESTED LOWER, DSNDED TO FL290. CABIN ALT STABILIZED FIRST THEN RESUMED CLB. REQUESTED 14000 FT. ATC APPROVED. IN INITIAL DSCNT, CABIN ALT REACHED 9800 FT AND RED CABIN ALT LIGHT ON MOMENTARILY. MAINTAINED 1.4 EPR WITH FULL SPD BRAKES AT BARBER POLE TO KEEP CABIN ALT FROM CLBING. THIS WORKED. PASSING FL240, CABIN ALT STARTED SLOW DSCNT 200 FPM. ASKED ATC FOR 17000 FT. RESUMED NORMAL CRUISE CONFIGN AT 17000 FT CABIN ALT. CONTINUED SLOW DSCNT (200 FPM) AS LONG AS EPR ABOVE 1.5 TO 1.7. APCHING ORD, DSCNT WAS NORMAL AS LONG AS EPR STAYED 1.4. BY 5000 FT, CABIN ALT AT FIELD ELEVATION AND REMAINED SO TO NORMAL DSCNT AND LNDG.
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.