Center Fuel Tank Usage

[imemyself]

Hi - checking fuel usage 6 hours into a ~8 hour flight, and I see all three tanks have the exact same amount of fuel remaining, despite starting with full wing tanks and only ~20k lb in the center fuel tank.  And going forward, It seems to be equally using fuel from both the wing tanks and center tank - all three are dropping at the same rate.  On the wing fuel tanks the "main" pumps are active per the fuel system page, as are both center fuel tank pumps.  After takeoff and flap retraction, I would expect the center fuel tank to be emptied first.

I'm pretty sure this is incorrect behavior - the FCOM describes the center fuel tank pumps as producing higher pressure, and effectively preferring the center tank over the wing tanks, and emptying it first (similar to most other Airbus aircraft).  Do you have documentation that indicates otherwise, or is this a mistake?

It does seem like someone else has seen similar behavior based on this Reddit post.

Thanks

[zero one]

I have also experienced this bug multiple times.

Using 2020 I did a test flight from RJTT-KDTW and it happened again. Things were fine from startup to cruise, the behavior of the pumps was correct. The center tank pumps were off until a couple minutes after Flaps 0 (even visually on the dispaly it showed them off too).  Then once they turned on the fuel drained only from the center tank. But about 55 mins into the flight when the center tank reached the same level as the wing tanks, they all began to drain equally. Interestingly because of the slight difference in the wings, the right tank started draining first when the center tank reached it's value, then about a minute later the left tank also started as the center and right reached it's level. They then continued to drain equally and I stopped the test.

Fuel Tanks L/C/R (LBS)
Before Start 52260/66120/52260
Line Up 51760/66120/51840  Center Pumps Visually Off
After TO Flaps 1 51140/66120/51240 Center Pumps Visually Off
Approx 7000ft 50520/65900/50620 Center Pumps Visually On
TOC FL350 50520/57140/50620
FLT 00:55 50520/50600/50600
FLT 00:56 50520/50520/50520
S/C FL370 483360/48360/48360