[A330] Fuel flow indications show lover number than real numbers

[Stas Harchuk 0]

I have noticed that the fuel flow indications almost all the time show lover numbers then what is actually used by the plan/sim.

 

I use my own flight data recording program (some thing like ACRAS but way more parameters recorded) to analyze my flights and aircraft performance.

 

On takeoff the plane show FF of around 7.5-8T per engine at 88% N1, but the real FF is more like 12-14T per engine.

On climb it show 5.5-8T but the real number are more like 10-12T per engine.

The difference on cruise is way smaller around 70-110Kg per engine.

 

 

 

 

 

[masterhawk 799]

We had a similar discussion long time ago. There was no need to edit anything.

We load a certain fuel amount, use a certain amount and the predictions are relatively well met at the end of the flight. So all is ok.

[Stas Harchuk 0]

WOW, not the respond that I was expecting, especially when small visual bugs (no flight impact whatsoever) are noted as bugs and fixed.

 

Why even show any numbers at all if you can't show the correct ones (basically just 2 variables that shown wrong - no flight dynamics impact).

 

I can't find the "similar discussion long time ago" topic.

 

 

[masterhawk 799]

32 minutes ago, Stas Harchuk said:

 

Why even show any numbers at all if you can't show the correct ones (basically just 2 variables that shown wrong - no flight dynamics impact).

As you write, no impact. But the values indicate what is expected compared to IRL indication.

Currently we focus on other items, and don’t rework items that look and feel correct.

And keep in mind, we don’t use the fuel system of the sim. So all is handled in a different way. It might be possible that sim variables don’t match our fuelsystem.

[Secondator 643]

I remember we did some extensive testing on the fuel usage before the release of the A330 on all segments: climb, cruise and descend comparing it with the real world data that we had available.

The fuel calculations fell within 3 % margin for each segment with long haul testing falling under 1 % margin from the real world estimations. I would say that is pretty close over multiple tests given that there are multiple variables at play here. 

[Stas Harchuk 0]

3 hours ago, Secondator said:

I remember we did some extensive testing on the fuel usage before the release of the A330 on all segments: climb, cruise and descend comparing it with the real world data that we had available.

The fuel calculations fell within 3 % margin for each segment with long haul testing falling under 1 % margin from the real world estimations. I would say that is pretty close over multiple tests given that there are multiple variables at play here. 

 

I am not talking about actual fuel usage which is good, rather the ECAM display that show way lower FF numbers than actual fuel usage at the moment (takeoff and climb) .

 

 

[masterhawk 799]

13 hours ago, Stas Harchuk said:

 

I am not talking about actual fuel usage which is good, rather the ECAM display that show way lower FF numbers than actual fuel usage at the moment (takeoff and climb) .

 

 

You have tool that read some sim variables, fine. And I told you, that we have a custom fuelsystem. So the simvariables are not reliable in this case, as you noted yourself.