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B737-800 flight crew experiences a dual bleed trip during a descent to FL360 causing a loss of cabin pressurization. Pressurization is regained during the descent but the crew elects to divert to a suitable airport.
| Attributes | |
| ACN | 1298431 |
| Time | |
| Date | 201509 |
| Local Time Of Day | 0601-1200 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | B737-800 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Pneumatic Valve/Bleed Valve |
| Person 1 | |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Person 2 | |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Inflight Event / Encounter Weather / Turbulence |
Narrative:
During cruise flight at FL380 while passing north of a thunderstorm; FMC sat temperatures went from -51* to -44* to -28*. We noticed ice building on windshield wipers and turned engine ant-ice on and asked for a lower altitude seeking a smoother ride. A FL360 descent was granted approximately 4 minutes later. As the descent was begun a right bleed trip off light illuminated and the cabin rate indicator showed a steady climb rate. While referencing the QRH bleed trip off procedure the left bleed trip occurred and the cabin altitude warning began. We started an emergency descent to 10;000 feet with 02 mask on and successfully restored the packs by pushing the trip reset switch. Since a higher than normal fuel burn occurred at a lower altitude; a diversion was commenced.
Original NASA ASRS Text
Title: B737-800 flight crew experiences a dual bleed trip during a descent to FL360 causing a loss of cabin pressurization. Pressurization is regained during the descent but the crew elects to divert to a suitable airport.
Narrative: During cruise flight at FL380 while passing north of a thunderstorm; FMC SAT temperatures went from -51* to -44* to -28*. We noticed ice building on windshield wipers and turned Engine Ant-ice on and asked for a lower altitude seeking a smoother ride. A FL360 descent was granted approximately 4 minutes later. As the descent was begun a right Bleed Trip Off light illuminated and the cabin rate indicator showed a steady climb rate. While referencing the QRH Bleed Trip Off procedure the Left Bleed Trip occurred and the cabin altitude warning began. We started an emergency descent to 10;000 feet with 02 mask on and successfully restored the packs by pushing the Trip Reset switch. Since a higher than normal fuel burn occurred at a lower altitude; a diversion was commenced.
Data retrieved from NASA's ASRS site 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.