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When the automatic air conditioning system malfunctioned enroute; the flight crew of a B747-400 utilized alternative methods to mitigate the loss of temperature control.
| Attributes | |
| ACN | 989775 |
| Time | |
| Date | 201201 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | ZOA.ARTCC |
| State Reference | CA |
| Aircraft 1 | |
| Make Model Name | B747-400 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Air Conditioning and Pressurization Pack |
| Person 1 | |
| Function | Captain Pilot Not Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 100 Flight Crew Total 15000 Flight Crew Type 4800 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
[We got an] EICAS 'trim valve' message. Procedure is to reset once; then; if unsuccessful; turn off 'trim air.' the reset was unsuccessful and we turned the trim air off. Cabin temperature was uncontrollable; with maintenance control guidance used captain's emergency authority to reset associated circuit breakers but this was unsuccessful. We continued with two pack operation in auto and/or manual as required to warm the cabin. This was acceptable but the cabin remained very cool and the passengers used blankets and coats as a supplemental source of warmth.
Original NASA ASRS Text
Title: When the automatic air conditioning system malfunctioned enroute; the flight crew of a B747-400 utilized alternative methods to mitigate the loss of temperature control.
Narrative: [We got an] EICAS 'trim valve' message. Procedure is to reset once; then; if unsuccessful; turn off 'Trim Air.' The reset was unsuccessful and we turned the trim air off. Cabin temperature was uncontrollable; with Maintenance Control guidance used Captain's Emergency Authority to reset associated circuit breakers but this was unsuccessful. We continued with two pack operation in auto and/or manual as required to warm the cabin. This was acceptable but the cabin remained very cool and the passengers used blankets and coats as a supplemental source of warmth.
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.