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Dispatched with the right engine bleed deferred inoperative the flight crew of a B757-200 then experienced the uncommanded closing of the left engine bleed and the associated loss of pneumatics for pressurization. While descending they started the APU and ultimately re-established pressurization from that source. They then continued to their original destination for a safe landing.
| Attributes | |
| ACN | 876800 |
| Time | |
| Date | 201003 |
| Local Time Of Day | 0001-0600 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Aircraft 1 | |
| Make Model Name | B757-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Pneumatic System Control |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 180 Flight Crew Total 18000 Flight Crew Type 5000 |
| Person 2 | |
| Function | First Officer Pilot Not Flying |
| Experience | Flight Crew Last 90 Days 250 Flight Crew Total 14000 Flight Crew Type 1026 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
Shortly after reaching cruise altitude the left engine bleed switch closed itself. The right bleed was deferred inoperative. First officer noticed pressure change in his ears. Outflow valve closed but cabin altitude was increasing. We requested lower altitude; started descent and started APU. Descending through about FL210 cabin altitude warning annunciated so we donned masks and established communications. Descending below 17;000 ft APU bleed valve opened and cabin altitude started down. Max cabin altitude was about 10;500 ft cabin masks did not deploy. Flight attendants noticed the pressure change and early descent. Some passengers noticed the pressure change and questioned the flight attendants who were good about leaving us to deal with the problem. We contacted them as soon as things were under control; asked them to put everything away as we were to cross the mountains at a lower altitude than normal so it might be turbulent. Remainder of the flight was flown normally with an uneventful landing.
Original NASA ASRS Text
Title: Dispatched with the right engine bleed deferred inoperative the flight crew of a B757-200 then experienced the uncommanded closing of the left engine bleed and the associated loss of pneumatics for pressurization. While descending they started the APU and ultimately re-established pressurization from that source. They then continued to their original destination for a safe landing.
Narrative: Shortly after reaching cruise altitude the left engine bleed switch closed itself. The right bleed was deferred inoperative. First Officer noticed pressure change in his ears. Outflow valve closed but cabin altitude was increasing. We requested lower altitude; started descent and started APU. Descending through about FL210 cabin altitude warning annunciated so we donned masks and established communications. Descending below 17;000 FT APU bleed valve opened and cabin altitude started down. Max cabin altitude was about 10;500 FT cabin masks did not deploy. Flight Attendants noticed the pressure change and early descent. Some passengers noticed the pressure change and questioned the Flight Attendants who were good about leaving us to deal with the problem. We contacted them as soon as things were under control; asked them to put everything away as we were to cross the mountains at a lower altitude than normal so it might be turbulent. Remainder of the flight was flown normally with an uneventful landing.
Data retrieved from NASA's ASRS site as of April 2012 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.