Ok so in accordance with the fuel card logic the reserve tank will gravity feed into Main Tank 2 and Main Tank 4 when their respective quantity drops below 18,200kgs.
Ok got that part.
Fuel temperature is meaured in Main tank 1 which together with #4 are the smaller tanks so the temp in #2 and #3 and CWT will always be higher because of larger quantity and therefore coldsoaking will take longer. Not to mention hot hydraulic fluid being cooled in these tanks.
Ok got that part also.
So here is my question.
Assuming we depart with full fuel, all tanks full.
Initially fuel from the center tank feeds all engines.
Then Main 2 feeds engine 1 and engine 2 and Main 3 feeds engine 3 and engine 4.
My point being you can spend a considerable amount of time at cruising altitudes before Main Tank 2 and 3 drop below the 18,200 for the gravity feed of the reserve tanks which are now cold soaked and at an unknown temperature.
I understand Main Tank 2 is still comnsiderable warmer because of the larger quantity an even Main Tank 1 is warmer as it still sits almost full.
So how do you prevent fuel of an unknown (colder then indicated fuel temp) temperature (and possible gelforming already taking place) from clogging pump inlets/filter screens and oil/fuel intercoolers aka the British Airways that flamed out on the ILS?
So basically 4000kgs of fuel in your wingtip is getting colder and colder and colder while waiting for space in another tank.
How long does it take to cool 4000kgs of fuel from 15C to -40C?
Yes, I have a tendency to overthink and miss the obvious...
