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B777 captain experiences a left fuel tank quantity indication failure in cruise; which also causes the failure of the total fuel indication. A fuel imbalance indication had briefly annunciated before the quantity failure and without any method to determine if a fuel leak existed the crew elects to divert.
| Attributes | |
| ACN | 1014071 |
| Time | |
| Date | 201205 |
| Local Time Of Day | 1801-2400 |
| Place | |
| Locale Reference | ZZZ.ARTCC |
| State Reference | US |
| Aircraft 1 | |
| Make Model Name | B777-200 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Fuel Quantity-Pressure Indication |
| Person 1 | |
| Function | Captain Pilot Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Experience | Flight Crew Last 90 Days 200 Flight Crew Total 28000 Flight Crew Type 7000 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical |
Narrative:
The preflight briefing indicated the right wing fuel tank gauge will be inoperative for the flight. When we got to the airplane; the maintenance paperwork indicated everything had been fixed. Two hours into the flight; the left wing tank showed a 20;000 pound imbalance with the right wing tank showing more fuel. The 'fuel disagree' checklist popped up and we started to complete it. Before completion; the total fuel indication disappeared along with the left wing fuel indications. We now; only had a right wing fuel indication. The 'fuel disagree' checklist was inadequate for this situation. We then elected to do the 'fuel leak' checklist and found it also inadequate; without a total fuel reading. The same was true for the 'fuel imbalance' checklist. After contact with dispatch and maintenance; it was concluded that a fuel leak was possible; but could not be verified visually; or by checklist. Without being sure the airplane was not leaking fuel; an immediate diversion was planned. Under this situation; we found the 'fuel disagree;' 'fuel leak;' and the 'fuel imbalance' checklists; inadequate to determine with certainty; whether the airplane was leaking fuel; or if the fuel sensors were the problem. Making the wrong assumption could lead to a serious problem.
Original NASA ASRS Text
Title: B777 Captain experiences a left fuel tank quantity indication failure in cruise; which also causes the failure of the total fuel indication. A fuel imbalance indication had briefly annunciated before the quantity failure and without any method to determine if a fuel leak existed the crew elects to divert.
Narrative: The preflight briefing indicated the right wing fuel tank gauge will be inoperative for the flight. When we got to the airplane; the maintenance paperwork indicated everything had been fixed. Two hours into the flight; the left wing tank showed a 20;000 LB imbalance with the right wing tank showing more fuel. The 'fuel disagree' checklist popped up and we started to complete it. Before completion; the total fuel indication disappeared along with the left wing fuel indications. We now; only had a right wing fuel indication. The 'Fuel Disagree' checklist was inadequate for this situation. We then elected to do the 'Fuel Leak' checklist and found it also inadequate; without a total fuel reading. The same was true for the 'Fuel Imbalance' checklist. After contact with Dispatch and Maintenance; it was concluded that a fuel leak was possible; but could not be verified visually; or by checklist. Without being sure the airplane was not leaking fuel; an immediate diversion was planned. Under this situation; we found the 'Fuel Disagree;' 'Fuel Leak;' and the 'Fuel Imbalance' checklists; inadequate to determine with certainty; whether the airplane was leaking fuel; or if the fuel sensors were the problem. Making the wrong assumption could lead to a serious problem.
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.