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Flight crew of a super MD80 lost pressurization while descending through FL330 resulting in the passenger masks dropping due to cabin rising to 14000 ft.
| Attributes | |
| ACN | 435112 |
| Time | |
| Date | 199904 |
| Day | Sun |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | navaid : txk.vortac |
| State Reference | AR |
| Altitude | msl single value : 33000 |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zfw.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | MD-80 Super 80 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other other vortac |
| Flight Phase | cruise : enroute altitude change descent : vacating altitude |
| Route In Use | arrival star : byp.byp3 |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 435112 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : multi engine pilot : commercial |
| Events | |
| Anomaly | aircraft equipment problem : critical |
| Independent Detector | other flight crewa other flight crewb |
| Resolutory Action | flight crew : overcame equipment problem |
| Consequence | other |
| Supplementary | |
| Problem Areas | Aircraft |
| Primary Problem | Aircraft |
Narrative:
During descent at approximately FL330 near glove intersection on byp 3 arrival to dfw, the cabin altitude light illuminated. Flow light was not illuminated. Pack pressure gauges normal. Standby pressurization controller selected. Emergency descent to 10000 ft. During descent, cabin pressurization controller placed to manual. Pressurization control wheel was jammed. Unable to close outflow valve. Outflow valve position indicator was abeam 40 degree flap position. Cabin altitude continued to climb as we continued descent. At 14000 ft, cabin altitude passenger oxygen masks deployed. Cabin altitude never exceeded 15000 ft. After leveloff at 10000 ft cabin pressurization controller placed to automatic and primary pressurization controller selected. Pressurization control seemed normal for remainder of flight. Since we had received clearance to descend to 11000 ft before pressurization problem, no emergency was declared.
Original NASA ASRS Text
Title: FLC OF A SUPER MD80 LOST PRESSURIZATION WHILE DSNDING THROUGH FL330 RESULTING IN THE PAX MASKS DROPPING DUE TO CABIN RISING TO 14000 FT.
Narrative: DURING DSCNT AT APPROX FL330 NEAR GLOVE INTXN ON BYP 3 ARR TO DFW, THE CABIN ALT LIGHT ILLUMINATED. FLOW LIGHT WAS NOT ILLUMINATED. PACK PRESSURE GAUGES NORMAL. STANDBY PRESSURIZATION CONTROLLER SELECTED. EMER DSCNT TO 10000 FT. DURING DSCNT, CABIN PRESSURIZATION CONTROLLER PLACED TO MANUAL. PRESSURIZATION CTL WHEEL WAS JAMMED. UNABLE TO CLOSE OUTFLOW VALVE. OUTFLOW VALVE POS INDICATOR WAS ABEAM 40 DEG FLAP POS. CABIN ALT CONTINUED TO CLB AS WE CONTINUED DSCNT. AT 14000 FT, CABIN ALT PAX OXYGEN MASKS DEPLOYED. CABIN ALT NEVER EXCEEDED 15000 FT. AFTER LEVELOFF AT 10000 FT CABIN PRESSURIZATION CONTROLLER PLACED TO AUTO AND PRIMARY PRESSURIZATION CONTROLLER SELECTED. PRESSURIZATION CTL SEEMED NORMAL FOR REMAINDER OF FLT. SINCE WE HAD RECEIVED CLRNC TO DSND TO 11000 FT BEFORE PRESSURIZATION PROB, NO EMER WAS DECLARED.
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.