See attached screenshot.

This was after running unattended at cruise for nearly 4 hours with all crossfeeds open and all pumps on. I am not using the PFD fuel balance helper (which also appears to not be working correctly, but that's a topic for a different post).

In my screenshot I've turned all pumps off but the tank 3 and 2R pumps to even out first the small imbalance in 2R and then I will try to burn tank 3 down.

Logged for the team

On 5/25/2026 at 8:54 PM, MediumRareBaku said:

This was after running unattended at cruise for nearly 4 hours with all crossfeeds open and all pumps on.

With your initial fuel load, you should have been running Tank to Engine with your crossfeeds closed. With all crossfeed valves open and all pumps on, you're basically seeing which pumps have the higher output...in this case, Tank 1 pumps. That's why you have an imbalance of 4,500 lbs between tanks 1 and 3.

On 5/31/2026 at 2:47 AM, CaptainCAVU said:

With your initial fuel load, you should have been running Tank to Engine with your crossfeeds closed. With all crossfeed valves open and all pumps on, you're basically seeing which pumps have the higher output...in this case, Tank 1 pumps. That's why you have an imbalance of 4,500 lbs between tanks 1 and 3.

Unless I'm mistaken, ini doesn't usually simulate variations between systems to the degree of certain pumps having higher outputs than other pumps, unless the pump for Tank 1 was significantly stronger on the real L1011 by design than the other pumps.

11 hours ago, MediumRareBaku said:

Unless I'm mistaken, ini doesn't usually simulate variations between systems to the degree of certain pumps having higher outputs than other pumps, unless the pump for Tank 1 was significantly stronger on the real L1011 by design than the other pumps.

ini obviously simulated something otherwise you wouldn't have a 4,500# imbalance. In actual practice, all 3 crossfeed valves would never be open at one time. Only 2 valves are needed to feed any engine from any tank and the preferred valves would be the left and right crossfeed valves.

The fuel pump's rated output was 30 psi but all it would take is one pump at 31 psi and all crossfeed valves open to end up with an imbalace.