Fuel selector bug

[Bob Scott 7,742]

The FSW Lear (v4.3c) has a bug in the fuel feed logic that's causing the left engine to feed off the right wing tank, resulting in imbalances.

I suspected at first this might be an initialization issue coming across from the default flight, so I monitored the #1 and #2 fuel selectors via FSUIPC offsets 3880 and 37C0, and I can see that, no matter how the default flight's fuel selectors are configured and after the Lear panel loads, the panel is setting the left fuel selector to feed from the right tank (selector value = 3) and the right fuel selector to crossfeed R to L (selector value = 15).

I wrote a lua script that autoruns via FSUIPC when the L35 panel is loaded which resets the selectors to 2 and 3 respectively, after which fuel feed behavior is normal.

[Flysimware 647]

We have code that loads the fuel selectors to what you discovered startup or any time you reload the aircraft. So you may want to look into why your setup is not updating. Inside the panel folder is a cab file called Learjet_35A. Extract that to a folder and open the systems.xml. The first section of code is to load presets. And what i shared below is in there. So yes you discovery is correct but is also an issue on your end.

	2 (>K:FUEL_SELECTOR_SET)
	3 (>K:FUEL_SELECTOR_2_SET)

 

Edited July 19, 2021 by Flysimware

[ark 1,295]

5 hours ago, w6kd said:

The FSW Lear (v4.3c) has a bug in the fuel feed logic that's causing the left engine to feed off the right wing tank, resulting in imbalances.

Bob,

In P3Dv4.5 I loaded the Lear35 v4.3C onto the runway with the brakes set, shut down the right engine, set the left throttle to 94% (N1 about 89%), set the tip tanks and center tank to 0% fuel, and the wing tanks to 100% fuel. I then monitored the fuel quantity (%) in the wing tanks with a little Lua script (FSUIPC offsets 0x0B94 and 0x0B7C). The right tank stayed at 100% while the left tank went from 100% down to less than 60% before I stopped the experiment. So at least on my system it doesn't seem the left engine is running off the right tank upon initial loading.

Al

Edit: In retrospect, rather than using a Lua script it is easier to just monitor the fuel tank quantities using the P3D dropdown Vehicle > Fuel and Payload...

Edited July 20, 2021 by ark

[Bob Scott 7,742]

Thanks Mark/Al

If I load the default scenario  (the LM default F-22 at Eglin AFB) and let it go all the way to ready-to-fly and then switch to the Lear, it initializes properly.  But if I select the L35 at the scenario startup dialog, it initially comes up with both selectors set to 1 (All) and then goes to 3 and 15 after ~5-10 seconds.  Watching the quantities, both engines are feeding off the right main.  Definitely repeatable.  Resetting the selectors with the Lua script repeating the settings for ~ 1 min after the panel completes loading solves the issue.

[ark 1,295]

1 hour ago, w6kd said:

If I load the default scenario  (the LM default F-22 at Eglin AFB) and let it go all the way to ready-to-fly and then switch to the Lear, it initializes properly. 

I always start with my Default flight which is the 'P3D default' F-35A on to R35L at KCOS. But once the sim loads the F-35A into the rotating vehicle selection (or whatever it is called) window, I then switch to the Lear35 so it is in the vehicle window. I then either press on so the Lear is loaded on to 35L at KCOS, or change the target airport.   I have found over time that starting in the rotating vehicle window with a 'simple' default aircraft (F-35A seems to work better than some) seems to help avoid strange problems.  Back in the FSX days PMDG cautioned to always load a default aircraft before loading one of their complex aircraft, and so I have been doing that ever since. I don't know if PMDG still recommends that.

Al

Edited July 20, 2021 by ark