Fuel transfer logic bug

[airforce2]

I am using version 1.4.1 of the Challenger.

There's a nasty bug in the fuel transfer logic.  When transferring I am seeing a drop in total fuel quantity, inconsistent transfer of fuel to the aux tank, and no aux tank scavenge pumping back to the main tanks when on boost pump pressure.

Scenario--acft on ground, powered by ground AC unit.  There is no fuel burn occurring, so in all cases total fuel quantity should be preserved as fuel is transferred between tanks.  Starting tank quantities are (LMain-Aux-RMain-Total in lbs) 2160-0-2170-4330.  Tail tank quantities remained zero throughout the test.

I turn on both boost pumps, and select L-to-Aux on the transfer panel and transfer for three minutes.  Then I allow one min for qualtities to stabilize.

Quantities after the transfer are 1880-0-2170-4050.  No fuel was transferred to the aux tank, and the LMain and Total quantities dropped by 280 lbs.

Then I transfer R-to-Aux for three minutes.  After stabilizing, quantities are 1880-120-1900-3900.  270 lbs left the RMain tank, 120 were added to the Aux, and total dropped by 150 lbs.

Then I transfer from L-Aux for three min again, leaving me with 1640-300-1900-3840.  240 lbs left the LMain tank, 180 lbs were added to Aux, and 60 lbs were lost from the system total.

In none of the cases did I see any scavenger transfer of fuel from the aux tanks back to the mains, which should be occurring with the mains at less than 93% and boost pump pressure.

I repeated this test three times after restarting the sim with similar results.

Regards

Bob

[Pils]

Please provide screenshots of the Fuel System Study window for these situations.

[airforce2]

OK, I hadn't played with the system study windows before this.  It looks like this is an indication problem, because the study window shows fuel transferring out of the L main and into the fwd aux tank, but the indications on the Captain's MFD do not reflect the transferred fuel in the aux tank quantity (still indicating zero after transferring 266 lbs from the L main to the fwd aux tank) and the total quantity indication has decreased 230 lbs from 4370 to 4140 lbs.

Here are the screenies--seq 1 is initial condition, seq 2 shows the panel config and study window after transferring for 3 min, seq 3 shows the study window and MFD indication a few seconds later.

Regards

Bob

 

[Pils]

Ok glad that helped. At low levels the fuels sensors (also its own study window) are very unreliable, maybe a bit too unreliable in the sim currently so that may be tweaked in a future release. But don’t expect the perfection, real life is analogue and noisy. Thanks for the report.