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Dispatched with one engine bleed valve deferred and closed; a B757-200 diverted to an enroute airport when the crew was unable to reliably control cabin altitude as they approached an area of weather.
| Attributes | |
| ACN | 853552 |
| Time | |
| Date | 200909 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | B757-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Pressurization Control System |
| Person 1 | |
| Function | Captain Pilot Not Flying |
| Experience | Flight Crew Last 90 Days 200 Flight Crew Total 17000 Flight Crew Type 4000 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Inflight Event / Encounter Weather / Turbulence |
Narrative:
During setup first officer discovered right engine bleed valve stuck open. Declined to accept aircraft in this condition because I wouldn't have any way to control an inflight duct leak except by shutting down engine. Dispatched with right engine bleed valve manually closed and deactivated; limited to single-pack operation; FL350 max altitude; no flight into known or forecast icing. Configured for left pack. Noticed the cabin alt slowly rising (~500 ft/min) and differential pressure decaying. Cabin reached 8200 ft and differential pressure reached 7 psi; opened isolated valve and ran cabin on right pack. Conferred with dispatch and maintenance control and decided to divert; partly due to large area of convective storms in the valley; which would have posed a problem if necessary to descend due to any further pressurization difficulty (icing prohibition.) descent; approach; landing; taxi to gate normal.
Original NASA ASRS Text
Title: Dispatched with one engine bleed valve deferred and closed; a B757-200 diverted to an enroute airport when the crew was unable to reliably control cabin altitude as they approached an area of weather.
Narrative: During setup First Officer discovered right engine bleed valve stuck open. Declined to accept aircraft in this condition because I wouldn't have any way to control an inflight duct leak except by shutting down engine. Dispatched with right engine bleed valve manually closed and deactivated; limited to single-pack operation; FL350 max altitude; no flight into known or forecast icing. Configured for left pack. Noticed the cabin alt slowly rising (~500 FT/MIN) and differential pressure decaying. Cabin reached 8200 FT and differential pressure reached 7 PSI; opened isolated valve and ran cabin on right pack. Conferred with Dispatch and Maintenance Control and decided to divert; partly due to large area of convective storms in the Valley; which would have posed a problem if necessary to descend due to any further pressurization difficulty (icing prohibition.) Descent; approach; landing; taxi to gate normal.
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.