ATR Fuel on Board (FOB) and Reserve Values do not Correlate

[Gugutoterell]

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2 tags are required: One for platform, and one for aircraft.

Are you using Developer Mode or made changes in it?

No

Have you disabled/removed all your mods and addons? If the issue still occurs with no mods and add-ons, please continue to report your issue. If not, please move this post to the User Support Hub.

Yes

Which aircraft are you reporting an issue about? (Please also add the proper tag for it)

ATR 42-600

Which aircraft version are you experiencing this issue on? (You can find this listed in the Content Manager under the Aircraft Name)

1.0.46

Brief description of the issue:

The Fuel on Board and Reserve values displayed in the Weight & Balance sheet, aircraft displays and FMC do not correlate with one another.

Provide Screenshot(s)/video(s) of the issue encountered:

Detailed steps to reproduce the issue encountered:

Load C&D into aircraft. Power on the aircraft and allow the displays to complete self-test. Display the A/C Data on right captain’s display. Enter 1590.5 LBS of fuel in each tank via the W&B sheet. Note the FOB values on both the A/C Data and central display do not match and all display a different value (red circles on screenshot). Enter the Weight section of the FMC, enter a Reserve value of 789 LBS. Note the Reserve value on the A/C Data display doesn’t match that of the Reserve entered in the FMC (blue circles on screenshot).

PC specs and/or peripheral set up if relevant:

N/A

Build Version # when you first started experiencing this issue:

Several versions prior to 1.38.2.0

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Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

If relevant, provide additional screenshots/video:

[Gugutoterell]

Do you have the same issue if you follow the OP’s steps to reproduce it?

Provide extra information to complete the original description of the issue:

Upon further examination, it appears that the Reserve displayed on the A/C Data page is the value in the EFB listed as “Contingency Fuel” rather than “Reserve Fuel”.

Again, however, the value entered in the FMC is the Reserve Value (here a value of 822 LBS.).

If relevant, provide additional screenshots/video:

[dxtr]

Do you have the same issue if you follow the OP’s steps to reproduce it?

yes

Provide extra information to complete the original description of the issue:

there are also always discrepancies between the values in the Flightplan tab of the EFB which you import from Simbrief and the FOB in the center display. The Aircraft tab of the EFB where younload the aircraft also shows different values than the plane itself, and what you enter there is not saved correctly, it feels very sketchy.

If relevant, provide additional screenshots/video:

[Ferrabrz]

Same thing here.

[A220driv3r]

To be clear, on the real ATR, the FOB displayed on the EWD (Engine Warning Display) and performance page is calculated and not sensed. It should directly follow what you enter into the FMS (both FOB and reserve fuel). It has nothing to do with what you have actually in the tanks.

If you enter 2000 kgs into the FMS as FOB while having 1000 kgs actually onboard, then the EWD and performance page will show 2000 kgs, not 1000 kgs. After engine start, the FMS subtracts the fuel used (sensed from fuel flow meters) from the FOB to calculate the FOB and this is what is shown on EWD and PERF page.

The only way to check the actual FOB is using the ENG & FUEL synoptic page. Of course it creates a caution message when sensed and FMS calculated fuel onboard differ too much. It doesn’t seem to do that so this is definitely a bug, just so everyone is aware what the correct indication is!