GTN 750 Fuel On Board (resolved)

[fppilot 4,351]

25 minutes ago, ark said:

Why do you ask? Doesn't make any difference either way.  Did you get different results?

Al

Not challenging you at all.  I have in the past encountered issues that when restarting the simulator disappear. You toggled the settings and that worked. Sometimes a restart of the simulator also corrects issues.   Been at this for many many years.  It can and does sometimes make a difference.  Obviously cannot say in your case, but it is a legitimate step to complete for testing and reporting any such issue, not just yours.  So please relax.

I do not have the Lear. I have not experienced the issue with other aircraft models.

Edited February 21, 2019 by fppilot

[ark 1,288]

4 minutes ago, fppilot said:

Not challenging you at all.  I have in the past encountered issues that when restarting the simulator disappear.  Been at this for many many years.  It can and does sometimes make a difference.  Obviously cannot say in your case, but it is a legitimate step to complete for any such issue, not just yours.  So please relax.

I do not have the Lear. I have not experienced the issue with other aircraft models.

You miss understand the intent of my question -- I was curious if there was something I was missing and you had different results.  So I have no need to 'relax', although some days I would certainly welcome the opportunity.

Based on the numbers, my hypothesis is that when the GTN starts up in pound fuel units, it defaults to using the weight of AVGAS (about 6 lbs/gallon) instead of the weight of JETA (about 6.7lbs/gallon). Thus the Baron58 numbers are correct, but not the Lear35 or King Air 350 numbers. But if you start the GTN in some other fuel unit besides pounds, when it then switches to pounds it uses the correct lbs/gal value for JETA.

Al 

[fppilot 4,351]

27 minutes ago, ark said:

But if you start the GTN in some other fuel unit besides pounds, when it then switches to pounds it uses the correct lbs/gal value for JETA.

Understand. So knowing Jean-Luc he will give this a hard look.

[bpcw001 22]

8 hours ago, ark said:

I have found that if the GTN750 is started up in the mode with the fuel units in pounds when the FSW Lear35 is loaded, the GTN displays the wrong value. But if the GTN is started up in the mode with the fuel units as gallons, the GTN displays the correct value, and if you then switch the units to pounds, the value will be correct.

I then tried the default Beech King Air 350 and get the same results. If the GTN750 is initially in the fuel pounds mode when the a/c is loaded, the GTN displays the wrong value.

The Beech Baron58, which uses AVGAS and not JETA like the Lear35 and King Air 350, did NOT have the above problem -- the GTN displayed the correct fuel weight in pounds.

So the problem seems to show up when the a/c is using JETA fuel and the GTN is initially (when first started) using pounds for the fuel units.

I used Win10/P3Dv4.4 for the above tests.

Al

Exactly my obervations!

[RXP 2,336]

Hi and thank you for your thorough investigation.

Now we'll have to find out whether this is solely a GTN trainer bug or not, but now that you've narrowed it down it will be easier for us to try repro and cure.

Somehow, if you also have the GNS V2 and it shows the same issue, there is a great chance the problem is in our code somehow.

Edited February 21, 2019 by RXP

[ark 1,288]

2 hours ago, RXP said:

Hi and thank you for your thorough investigation.

Now we'll have to find out whether this is solely a GTN trainer bug or not, but now that you've narrowed it down it will be easier for us to try repro and cure.

Somehow, if you also have the GNS V2 and it shows the same issue, there is a great chance the problem is in our code somehow.

Unfortunately Jean-Luc I do not have the GNS V2 to check. My guess is that if the GTN is initially started (powered up) in the pounds fuel mode,  for some reason it does not read the fuel type from the aircraft.cfg (or initially uses the wrong pounds/gallon value for JETA) and in effect "defaults" to AVGAS as the initial fuel type. The fuel numbers I was getting seem to indicate the GTN on power up was using 6lbs/gal instead of 6.7lbs/gal although the fuel type was JETA .

Al

Edited February 21, 2019 by ark

[RXP 2,336]

@ark and you are perfectly right! It is a 'who's first' initialization issue with the fuel type prior powering up. We've overlooked this one obviously. Thank you all for your astute help with this! Unfortunately it will have to wait for the next update for a fix.

[bpcw001 22]

1 hour ago, RXP said:

@ark and you are perfectly right! It is a 'who's first' initialization issue with the fuel type prior powering up. We've overlooked this one obviously. Thank you all for your astute help with this! Unfortunately it will have to wait for the next update for a fix.

Thanks for the information. At least the issue has been identified now.

Looking forward to the next update!

[ark 1,288]

7 hours ago, RXP said:

@ark and you are perfectly right! It is a 'who's first' initialization issue with the fuel type prior powering up. We've overlooked this one obviously. Thank you all for your astute help with this! Unfortunately it will have to wait for the next update for a fix.

Jean-Luc -- I sincerely appreciate your willingness to take the time to investigate issues reported by your customers. Thanks for the outstanding support.

Al

[RXP 2,336]

Hi,

v2.5.14 is now released with a fix for this and other things!