Hi guys,
In the absence of a GPU, the APU must be started to support the batteries so my question is that for extended APU ops should all fuel pumps be turned on or should only one of the left wing tanks be turned on? I ask because I have observed that a small imbalance develops between the port and starboard wing tanks when one wing tank pump is turned on.
I know that in the first officers pre-flight procedures, all pumps are turned on but by the time this is done an imbalance has already developed. So I basically want to know if it's okay to turn on all fuel pumps once battery dependent electrical power is established. I tried doing this in a full flight simulator and there was no imbalance because center tank fuel was used.
Since I noticed this on a full flight sim I'm not too sure how it works in the real world depending on airline SOPs and all. Input will be appreciated.
Cheers!