B747-400
Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Time Pressure; Situational Awareness; Confusion; Distraction; Human-Machine Interface
Aircraft Equipment Problem Critical; Inflight Event / Encounter Fuel Issue
General Maintenance Action
Aircraft
Upon arrival at the aircraft for the trip to two foreign airports we were informed by Maintenance that the number one fuel indication was inoperative; and an MEL was issued and complied with by manually entering the fuel on the PERF page. Fuel calculations were carried out in accordance with standard company procedures in flight. Approximately 30 minutes into the flight; the number one fuel indication repopulated; as did the totalizer; but we continued to operate per the MEL. Approximately 1 hour and 20 minutes into the flight to the first destination; at FL310; we received a FUEL PRESS ENG 1 EICAS message; approximately 10 minutes after selecting tank to engine fuel configuration. Upon viewing the fuel secondary EICAS page; it was noted that both main fuel pumps in tank 1 indicated amber. Simultaneously; engine 1 rolled back to 30% N1; with no secondary indications. QRH procedure was run in its' entirety and upon selecting override pump 2; engine 1 returned to normal N1; in line with the other 3 engines. We called Operations to explain the situation and look for a suitable landing site; which had to be our destination due to lack of fuel to turn back; and ops direction not to divert into a not totally friendly country. For reference only; due to the MEL; and to further explain what we were seeing in the cockpit regarding our fuel quantities; I will now mention the fuel numbers visible to the crew on the secondary EICAS. Per the QRH procedure; when appropriate; we selected the transfer 1 and 4 to on. At this point; all four engine fuel indications were approximately 14;000 LBS. Number 4 began to transfer immediately; however; number one did not start to transfer for approximately 20 minutes; at which time it transferred 4;000 LBS to tank 2; and abruptly changed indicated fuel from 9;000 LBS to 0.0; triggering a FUEL QUANTITY LOW EICAS message. QRH procedure was run for this procedure as we were entering destination country airspace. We declared minimum fuel for the rest of the flight and utilized an autoland on Runway 03; without further incident. Upon blocking in; the Totalizer for tanks 1 to 4 read 0.0; 7.1; 11.6 and 4.0 respectively. Approximately 10 minutes after block in; the number 1 tank changed to 14.7; with no changes made to the fueling quantity or system. The fuel quantity MEL remained in place; again; I only offer these numbers to further clarify what the crewmembers were seeing during operations.
A B747 fuel indication system was MELed prior to departure and the quantity became erratic in flight. At one point; the tank one pumps indicated amber and the engine RPM rolled back until pump override was selected.