B747-400
Flight Crew Last 90 Days 138; Flight Crew Total 14928; Flight Crew Type 398
Situational Awareness; Troubleshooting; Communication Breakdown
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance; Inflight Event / Encounter Fuel Issue
General Maintenance Action
Human Factors; Company Policy; Procedure; Aircraft
This B747 aircraft has a chronic unwanted fuel transfer problem in flight. It's been written up 10+ times in the last three months. Each time Maintenance just does a test of the Fuel Quantity Indicating System (FQIS) and signs it off; or else finds something convenient and easy to defer so they can keep the airplane moving. Discrepancy noted in October 2013 describes the problem exactly. Prior to reaching a Tank-to-Engine Configuration; fuel is disappearing from Main tank #1 when it shouldn't. Also; prior to reaching Tank-to-Engine; but after depleting the Center tank; Main tank #3 decreases faster than Main tank #2. This all happens with the engine fuel flows matched perfectly. The tanks have been dripped to confirm the accuracy of the cockpit gauges. There is nothing else this could be but an unwanted transfer or a leak. After this flight; a Mechanic told me that a crew needs to refuse this airplane so they can get it into the Hangar and do a thorough troubleshooting job. But here's the problem with that... The maintenance history presented to the crew during flight planning only shows the last twenty items of history. This list is almost completely populated with cabin defects (reading lights; video monitors; etc.); so it masks the real problems with the airplane. There is no way for a crew to know that there is three months of history on a fuel system malfunction unless they remember the airplane from a previous flight and go looking for it -- which is how I stumbled across it. The maintenance history presented to the crew really needs to be stripped of non-essential items so the crew can focus on actual system malfunctions. There are not a lot of places to land in the middle of the Ocean. Somebody needs to fix the fuel system problems in this airplane before they lead to something bigger.
Reporter stated he's noticed that some pilots don't look at the 'Tank to Engine Fuel Configuration' until later in the flight. But when he reviewed the history of the B747-400 he was flying; he noticed several issues with the Fuel Totalizer not matching with the calculated fuel on the FMC.  In fact; the Totalizer fuel was always 'less' than calculated. The Totalizer readings are based on the Fuel Quantity probes in the tanks whereas the calculated fuel comes from the FMC; starting with the original fuel amount; minus what is burned. But when the fuel tanks were dripped; the gauges matched. There were ongoing differences between the Tank Quantities and the Totalizer. But each time the Fuel Quantity Indicating System (FQIS) was tested; the results were 'no faults found'; write-ups were signed-off.Reporter stated fuel procedures are to burn down (use) Center tank fuel first; than burn down fuel from #2 and #3 tanks until the burn down level is equal in quantity with #1 and #4 Outboard tanks. At that point; the crossfeed valves are closed and each fuel tank supplies fuel to directly to the associated engine. His air carrier recently performed a Boeing Health Monitoring Program check that noted a fault and Maintenance replaced the #2 Engine Fuel Flow transmitter. His discrepancy was signed-off.  But #2 Engine had nothing to do with the problem of fuel in #1 Tank disappearing; or experiencing unwanted fuel transfer; way before the 'Tank to Engine Configuration' was even ready to be applied. When all the 'Tank to Engine Fuel Configurations' and engine fuel flows were matched; fuel in #3 Tank was disappearing faster than the other tanks. They could not determine where the fuel was going by looking at the tank gauges. He just saw another write-up where fuel was pouring out of the right wing surge tanks on the same aircraft; the flight was cancelled.
A First Officer reports that a company B747 aircraft has chronic unwanted fuel transfer problems in flight that have been written up 10+ times in the last three months. Fuel is disappearing from Main Tank #1 when it should not be; and after depleting the Center Tank; Main tank #3 decreases faster than Main tank #2.