737NGX sinks into runway due to fuel overload

[Tomek Albrecht 0]

Hi

First of all, apologize but I couldn't find a fix for that. The problem is described in the title. I found that FMC shows hudge overload with fuel,

 

[Bob Marton 39]

can you post a photo? Maybe the aircraft sinking is actually an airport elevation issue.

[Olympic260 415]

1 hour ago, Tomek Albrecht said:

Hi

First of all, apologize but I couldn't find a fix for that. The problem is described in the title. I found that FMC shows hudge overload with fuel,

 

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For your issue 99% you are not loading the plane in the sim correctly. Ie your startup situation should be the select flight/load scenario screen with the default Trike/F22 (depending sim you are using). From there select the ngx and select fly. Having as a start up situation a complex addon (ours or another) or loading a PMDG on top of another will cause these issues.

[Tomek Albrecht 0]

[Tomek Albrecht 0]

[Tomek Albrecht 0]

I can change this value after I click P (pause)and then immediatelly go to the FMC FSoption>FUEL. Then it works properly.

Had the same situation once came back from crash and airplane after reload suddenly felt to the ground because of weight >700000 kgs!!!.

Regards

Tomek A.

[Tomek Albrecht 0]

 

48 minutes ago, Olympic260 said:

.....

For your issue 99% you are not loading the plane in the sim correctly. Ie your startup situation should be the select flight/load scenario screen with the default Trike/F22 (depending sim you are using). From there select the ngx and select fly. Having as a start up situation a complex addon (ours or another) or loading a PMDG on top of another will cause these issues.

I will try to use  PMDG airplanes only.

[Olympic260 415]

2 minutes ago, Tomek Albrecht said:

 

I will try to use  PMDG airplanes only.

You should not have any complex addon as a start up state.

[Tomek Albrecht 0]

What do you mean by complex addon? ORBX, FreeMeshEU? There is also a problem with graphics inside the plane. Screenshot as soon as possible.

[Bob Marton 39]

complex addon= PMDG aircraft.

In other words, when you open up the flight planner in FSX the image should be the trike light aircraft not a PMDG aircraft for example

[Tomek Albrecht 0]

4 minutes ago, Bob Marton said:

complex addon= PMDG aircraft.

In other words, when you open up the flight planner in FSX the image should be the trike light aircraft not a PMDG aircraft for example

OK, I understood that is should be PDMG aircraft. Since there was trike as default + default location. I will check and back with findings. Could you please check why my cocpit contains old textures?

[scandinavian13 5,192]

4 hours ago, Tomek Albrecht said:

OK, I understood that is should be PDMG aircraft

Should NOT be.

4 hours ago, Tomek Albrecht said:

Since there was trike as default + default location

This is what it should be.

4 hours ago, Tomek Albrecht said:

Could you please check why my cocpit contains old textures?

What's wrong with them?

[MarkJHarris 128]

Don't understand. That's just full tanks and a 737NG can fly at 77,999kg  from most decent runways?

[Yves77 1]

The problem of the fuel overload appears if you change from one PMDG livery to another without exiting and restarting the sim. This is a new bug introduced with the P3Dv4 version of the PMDG planes. I've never had it in FSX, P3Dv2 and v3 (and could not reproduce it now). The PMDG777 is affected the same way. I don't have the other PMDG aircraft yet.

The manual states that PMDG planes should not be loaded on top of each other or on top of a 3rd party aircraft. But this was written years before the fuel bug existed. Switching the livery or the PMDG aircraft type has worked anyway in P3Dv3 most of the time, at least the errors (if any) were not directly visible. Now in P3Dv4 the fuel bug forces a restart. This might explain the several threads in this forum about this issue since the P3Dv4 update was released (the first thread here is from July 2017).

I did some investigation of what exactly happens with the fuel tanks in the PMDG737-800:

Upon reloading the 737NGX the current fuel amount (that was in before reloading) in the center tank is multiplied by 42.99. The right and left tank amount is multiplied by 12.88 each. Where are these strange figures from? They are defined in the aircraft.cfg under [fuel]. The capacity of the center tank is 4299 US Gals, left and right tanks hold up to 1288 US Gals.

[fuel]
Center1=  -1.884,   0.000, -1.800, 4299.000, 0.000
LeftMain= -9.110, -16.500,  1.600, 1288.000, 0.000
RightMain=-9.110,  16.500,  1.600, 1288.000, 0.000

After each consecutive reload or livery switching the fuel amount is again multiplied by these numbers. The gross weight becomes so high that the planes sinks into the ground and starts shaking. The true fuel amount in the tanks is always indicated in the regular payload & fuel menu of P3D. The FMC fuel indication is wrong in this situation, only the gross weight is correct.

You can reduce the fuel amount in the FMC fuel page, but it won't help. If you click 1/3 or 2/3 the tanks are correctly refilled, but the FMC shows a much too low fuel level. As a consequence, one gets an engine flameout after a few minutes, because the FMC *thinks* the tanks are empty (the flameout seems to relate on the FMC indication, not on the true fuel amount).

I hope PMDG will have a look at this, although it only happens outside of their recommended usage.

 

 

[kevinh 409]

It isn’t a bug as such because PMDG state you should not load it over itself. You’ll even get a warning message if you try. If you choose to load the sim in a non recommended manner you must expect issues like this.