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Widebody aircraft fuel system developed transfer and balance issues uncommanded. The aircrew diverted enroute as a precaution.
| Attributes | |
| ACN | 1340574 |
| Time | |
| Date | 201603 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Make Model Name | Widebody Transport |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise Parked |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Fuel Distribution System |
| Person 1 | |
| Function | Pilot Flying Captain |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Person 2 | |
| Function | First Officer |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Inflight Event / Encounter Fuel Issue |
Narrative:
Assigned aircraft with 5 mels including a main tank 2 transfer pump inoperative. Procedure was to operate the fuel system controller (fsc) in manual. Discovered in the aircraft maintenance log (aml) that aircraft had departed with this MEL and upon arrival; the inbound crew wrote up uncommanded fuel transfer enroute. They apparently found it necessary to rebalance fuel throughout the flight. We questioned maintenance about the two writeups and they were convinced the fuel transfers were related to the inoperative transfer pump.soon after departure; it was evident that the uncommanded transfer was still occurring. We monitored it for a short while after established in cruise -- and specifically avoided any attempt at rebalancing so as not to further mask the real problem or induce yet another problem. We concluded that something very significant was happening and coordinated with company for a diversion. We recorded the fuel used and fuel quantity data at various points while in flight and at block in it clearly showed that fuel was either; a) being transferred tank to tank uncommanded; or B) the quantity indications were unreliable. This data is being retained by the captain and can be presented if desired.
Original NASA ASRS Text
Title: Widebody aircraft fuel system developed transfer and balance issues uncommanded. The aircrew diverted enroute as a precaution.
Narrative: Assigned aircraft with 5 MELs including a Main Tank 2 Transfer pump inoperative. Procedure was to operate the Fuel System Controller (FSC) in manual. Discovered in the Aircraft Maintenance Log (AML) that aircraft had departed with this MEL and upon arrival; the inbound crew wrote up uncommanded fuel transfer enroute. They apparently found it necessary to rebalance fuel throughout the flight. We questioned maintenance about the two writeups and they were convinced the fuel transfers were related to the inoperative transfer pump.Soon after departure; it was evident that the uncommanded transfer was still occurring. We monitored it for a short while after established in cruise -- and specifically avoided any attempt at rebalancing so as not to further mask the real problem or induce yet another problem. We concluded that something very significant was happening and coordinated with Company for a diversion. We recorded the fuel used and fuel quantity data at various points while in flight and at block in it clearly showed that fuel was either; A) being transferred tank to tank uncommanded; or B) the quantity indications were unreliable. This data is being retained by the Captain and can be presented if desired.
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.