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A B747-400 flight crew noticed that; although the fuel synoptic was indicating fuel to all four engines was being delivered from main tank number 2--despite both override pumps being off--that fuel was being burned per the normal fuel management schedule. They then discovered that the central maintenance computer had noted the display fault the previous day; but the anomaly had not been addressed by maintenance.
| Attributes | |
| ACN | 1024403 |
| Time | |
| Date | 201207 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZAN.ARTCC |
| State Reference | AK |
| Aircraft 1 | |
| Make Model Name | B747-400 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Indicating and Warning - Fuel System |
| Person 1 | |
| Function | Pilot Not Flying Relief Pilot |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 250 Flight Crew Total 12000 Flight Crew Type 4000 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy |
Narrative:
Fuel system synoptic showed fuel flowing from main tank 2 override pumps despite pumps being turned off (feeding tank to engine). Also showed no fuel flowing from any other center source (main 2 or 3) despite both eng pumps in mains 2 and 3 being selected on. Obviously no fuel was being supplied by ovrd pumps due to symmetrical fuel usage from main tanks 2 and 3. Issue corresponded to a cmc [central maintenance computer] message indicating 'fuel supplied from fwd main 2 ovrd pump despite switch off.' that message was dated the day before we departed. Since the cmc is not a pilot preflight item; but is required of maintenance; it seems someone should have caught that prior to our flight. Had the fuel actually been fed by an override pump that could not be turned off; we could have had a severe fuel balance issue. Also could have resulted in yet another large aircraft stuck in an out station requiring involved maintenance. Seems like a trend lately.
Original NASA ASRS Text
Title: A B747-400 flight crew noticed that; although the fuel synoptic was indicating fuel to all four engines was being delivered from main tank number 2--despite both override pumps being off--that fuel was being burned per the normal fuel management schedule. They then discovered that the Central Maintenance Computer had noted the display fault the previous day; but the anomaly had not been addressed by Maintenance.
Narrative: Fuel system synoptic showed fuel flowing from main tank 2 override pumps despite pumps being turned off (feeding tank to engine). Also showed no fuel flowing from any other center source (main 2 or 3) despite both eng pumps in mains 2 and 3 being selected on. Obviously no fuel was being supplied by ovrd pumps due to symmetrical fuel usage from main tanks 2 and 3. Issue corresponded to a CMC [Central Maintenance Computer] message indicating 'fuel supplied from fwd main 2 ovrd pump despite switch off.' That message was dated the day before we departed. Since the CMC is not a pilot preflight item; but is required of Maintenance; it seems someone should have caught that prior to our flight. Had the fuel actually been fed by an override pump that could not be turned off; we could have had a severe fuel balance issue. Also could have resulted in yet another large aircraft stuck in an out station requiring involved Maintenance. Seems like a trend lately.
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.