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A g-iv flight crew initiated and emergency descent when the cabin altitude began to climb uncontrollably. Upon stabilizing the cabin while maintaining FL240 they determined the cause to be the left engine pneumatic bleed valve that had shut off.
| Attributes | |
| ACN | 1022972 |
| Time | |
| Date | 201207 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | Gulfstream IV / G350 / G450 |
| Operating Under FAR Part | Part 91 |
| Flight Phase | Cruise |
| Route In Use | Direct |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Pneumatic Valve/Bleed Valve |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 60 Flight Crew Total 7850 Flight Crew Type 2900 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
While in cruise; the cabin altitude began climbing at an uncontrollable rate. The 'emergency descent' checklist appeared on the crew alert system. We donned our masks; advised ATC and followed the 'emergency descent' checklist. The cabin regained pressurization and we leveled off at FL240. The QRH led us to check the bleed air pressures from both engines. We noted that the left bleed air valve had shut off. We completed the 'bleed air system failure' checklist. Normal flight was then continued to our destination.
Original NASA ASRS Text
Title: A G-IV flight crew initiated and emergency descent when the cabin altitude began to climb uncontrollably. Upon stabilizing the cabin while maintaining FL240 they determined the cause to be the left engine pneumatic bleed valve that had shut off.
Narrative: While in cruise; the cabin altitude began climbing at an uncontrollable rate. The 'Emergency Descent' checklist appeared on the Crew Alert System. We donned our masks; advised ATC and followed the 'Emergency Descent' checklist. The cabin regained pressurization and we leveled off at FL240. The QRH led us to check the bleed air pressures from both engines. We noted that the left bleed air valve had shut off. We completed the 'Bleed Air System Failure' checklist. Normal flight was then continued to our destination.
Data retrieved from NASA's ASRS site as of July 2013 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.