B777 Undifferentiated or Other Model
Flight Crew Last 90 Days 200; Flight Crew Total 10000; Flight Crew Type 5000
Troubleshooting; Situational Awareness; Human-Machine Interface; Confusion; Distraction
Aircraft Equipment Problem Less Severe; Inflight Event / Encounter Fuel Issue
General None Reported / Taken
Procedure; Aircraft
We had a fuel imbalance and after starting the checklist we noticed that the checklist only assumes that there is a possible fuel leak and/or fuel imbalance. The checklist should also include possible sensor/s failure (contamination) and/or gauge error/malfunction. From previous discussions with Maintenance; water contamination effects the sensors; which give an incorrect reading. In many instances this is the cause of imbalance indication [when]; however; there is no actual imbalance. If the checklist is run as stated; a self induced imbalance would be generated.
While following the checklist for a possible fuel imbalance the flight crew of a B777 noted it provided only for an actual imbalance or fuel leak; ignoring possible sensor or gauge faults.  If the source of the error is a sensor/indicator fault the procedure runs the risk of a self induced actual imbalance.