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nickpike

Fuel flow with engines off

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Hi, (A:ENG1 FUEL FLOW PPH, pounds per hour)still give a value even with the engines, APU and everything off. Any ideas?cheers,nick

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Nick,I'm so new to this xml that my brain is bustin, however, maybe what you might try is a if then conditional.If engine1 operatin and if fuel pumps on and pwr available to pumps then Fuel flow available=true els gauge shows zero. I could not even begin to suggest the code to emulate that statement.I have come across a lot of bugs in my on going build of the overhead 737-400 panel some in the fuel system but a lot in the electrics but I'm still learning.This old dog can still learn new tricks,!Douglas Ret B-707

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Nick,ENG FUEL FLOW is linked to N2 rotation. When you shut down an engine using its fuel cutoff switch, the logic says this Avar should turn to zero; however this is not FS logic here :-) and it will give a positive number as long as N2 decelerates to full stop.To avoid this "inconvenience" I've coded an LVar that effectively goes to 0 at fuel cutoff.Tom

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Thanks Tom. I have assigned an L:variable to each engine flow so can manipulate that to zero. However, before I did this, there was still flow with N2 at zero. Problem is, (A:FUEL TOTAL QUANTITY WEIGHT, pounds)is used as a readout, and this continues to drift downwards.Anything in the cfg or air files to set flow to zero with engines off, I wonder.cheers,nick

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If I recall correctly, it's been stated before that the fuel flow never goes to zero. I don't think anyone's found a work-around to get it to stop using fuel when nothing's running.

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""If I recall correctly, it's been stated before that the fuel flow never goes to zero.""In my 757 ENGn FUEL FLOW is 0 as long as N2 is 0, and at that moment there is no fuel consumption at all.If Nick or someone else reads a constant positive FF with 0 N2, then maybe a fuel var in aircraft.cfg has some kind of influence. Actually I've made such a lot of changes in my 757 engine tables that I honestly don't know which parameter could be related to this weirdness.Tom

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After a lot of tweaking and testing, I found a fix for my particular problem in the air file thus.To correct for zero fuel flow with engines off. Air file. Section 1506. Mach index 0, Y axis should be set to zero. In fact, all curves (both?) should go to zero.cheers,nick

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Nick, are you speaking of table 1506, CThrust Factor vs CN1? If so, then both Mach 0 and .90 should be CTF=0 for CN1=0 . Thrust is not supposed to exist when ©N1 is zero (at least in MSFS).Tom

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Yes, sorry, I meant table 1506, although they look like graphs to me:-)We had a little bit of thrust set for some reason and this produced a significant fuel flow. cheers,nick

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