Fuel system logic bug

[stefans85]

Hey guys,

in the real 737 classic the APU is fed from left tank via an DC pump. To lower maintenance on it we switched on an AC fuel pump so the pressure triggered the DC pump to go off. If there was an imbalance we could switch on an right hand AC pump and opened cross feed valve so it drains from right fuel tank. The fuel feed system does not simulate this as it even drains from left tank. Not yet simulated? Are fuel feed lines simulated at all?

Kind regards

Stefan

[Litjan]

Known issue, it is on my list.

The APU does not get fed from the left tank (this is a common misconception), it is fed from the left side of the fuel manifold. Otherwise balancing could never work as the fuel could not reach the feed line (there is a check-valve to prevent inadvertent transfer of fuel into the tanks).

This misconception is what caused us to code it like this at first (I also believed it was fed from the left side tank).

Edited December 10, 2023 by Litjan

[dr_anthony]

Add to that, in 1.5.2 doesn't work suction feed from center tank to wing tanks. Fuel indicator always show 70 kg in center tank 

[Litjan]

Hmm - I will have to doublecheck the logic. Did you trigger starting the scavenge pump?