If you want a Honeycomb Alpha for Christma you better order fast because we are quickly running out of stock!

Jump to content
Sign in to follow this  

Fuel Loading vs. Capacity

Recommended Posts

More of a notice to others regarding the increased fuel capacity "fix" myself and others have promoted (link below) as I realize it's unsupported.


I'm currently running a flight which I believe to be the first I've run where I've filled the aircraft up into the "additional" capacity range (i.e. above 19150 kg total or 2180 gal/14600 lb in the center tank).  KSFO-KBOS, with a block of 45900 lb or 20820 kg (GSX actually loaded it to 45940 lb).  I noticed during climb out that my fuel wasn't declining as quickly as it should be, whereas my total F.USED was showing the expected amount.  Turns out that something is causing the total FOB to increase during periods where the ECAM showed that transfers were occurring.






Note that despite this, the following all show correct numbers:


  • The P3D "fuel and payload" dialog
  • F.USED on the CRUISE, ENGINE (though incorrectly in KGS) and FUEL ECAM displays
  • GW in the lower right of the lower ECAM
  • FOB on the MCDU FUEL PRED page
  • Current burn on the flight is also within a few % of where SimBrief says it should be (I track weighted average fuel usage so my perf factors are generally quite good; I use 1.03 for the A321IAE.)


Not shown, the fuel panel mode selector is also displaying a fault.  I don't believe I've noticed this before.  Playing around with that and the center fuel pumps manually doesn't really seem to be causing much of a different behavior, even after getting the center tank to display below 14600 lb and back into the "supported" realm (without going manual it doesn't seem to dip below that value); the value shown in the FUEL ECAM does continue to decline (along with the wing tanks) despite the pumps being turned off.  As time goes by without transfers, the gross sum of the reported tank volumes and engine burn does seem to slowly be decaying (currently it's still at a total above the original loading, and for that matter, actual capacity, but I'm not sure the flight will be long enough to catch up if it indeed actually will).


I guess the first question is has anybody else who has applied this "fix" encountered this same issue?  I've yet to see feedback saying so, but perhaps they, as I did, applied it without ever actually utilizing it.


I looked through some of the XML files to see if there was something that stood out but didn't find any smoking guns.  Does it make sense that this could happen, and if so, would it be possible to re-code a file somewhere to allow capacities above the standard 2180 gal to just come out of the center tank as those from 1 to 2180, "realism" be damned?  (Even if not officially released or sanctioned but rather as a your mileage may vary; I'm not going to open a support request if I knowingly break something!  I also keep backups!)


I'll try it again sometime without "GSX Services" enabled just to confirm (I used that to load fuel and I have been having some weird results with that regarding PAX loading as well, and just want to rule it out).  It happened fairly quickly into the climb out so it shouldn't be a lengthy trial to attempt to replicate it.  In the meantime I'm continuing with my flight and just calling it a faulty center tank sensor and if I have a double flame-out over Chicago or have to land a little hot in Boston because the plane thinks its heavier than it is, so be it lol.



Share this post

Link to post

OK, I officially don't know what's happening - I turned off the GSX integration and rolled back the modifications to vanilla, loaded a fuel amount well less than the default capacity (say 40.00 klbs), and still seeing the increasing FOB once the transfers from the center tank begin shortly after takeoff. 


Situation:  Load state ready for takeoff at KSFO, Rwy 28L at 1850z+/- 10Jul2019, TRUKN2 departure, ORRCA transition.  I get this behavior before hitting ORRCA every time with the A321 IAE - although technically speaking I can also just sit there with nothing programmed and parking brakes on while running up the engines to TOGA and it'll still happen once the wing tanks get low enough, about 13250 lbs.  If I use a smaller total fuel quantity (say 35.00 klbs), the FOB doesn't increase but its rate of decrease seems to lag behind the increase in the F.USED.


Only seems to be happening to the A321 IAE.  Did something break with the update, because I don't remember this happening prior?

Share this post

Link to post

Upon further review what I'm seeing here doesn't seem to be a result of my modifications but rather the same issue as this:



Share this post

Link to post

Affirm, I believe it is indeed the same issue that has been discussed already on the linked thread. This will be fixed on the next experimental update at least when there is no modifications made by the user.

Share this post

Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Create New...