Calibrating GRT fuel gauges

[RV8iator]

Question, I have a pretty good understanding of how to calibrate the fuel gauges in the GRT but want to clarify something.
I know to set the SF to 100 and the offset to 0 in the EIS. I know to put a couple gallons at a time in an then?

In the GRT under the Engine Limits the last line to select is the Fuel Cal Chart.

Here's where I get lost. What reading goes is what box? Probe/Actual..
Greek to me. Can somebody that's done it successfully help me out here and walk me through just this last part?

[Mike S]

Originally Posted by RV8iator

Can somebody that's done it successfully help me out here and walk me through just this last part?

Ditto.

It is the "done it successfully" part that keeps me out of the running.

I got mine close, and have decided to live with it-------I did make a fuel dip stick while I was pouring in the measured 5 gallons, so at least I have an accurate measurement while on the ground.

And, the fuel flow totalizator is extremely close.

I recommend that anyone who is going through the "add a gallon" process to calibrate the fuel gauges, also make a dip stick at the same time.

Easy, simple, and fool proof.

[Mike D]

I have done it successfully, but I am half way across the world and don't have my notes.

So, from memory, you record the probe number frr each gal en and go through the worksheet in the EIS manual to come up with new numbers for the SF and offset. Enter these new numbers and make sure it is reading a positive number that makes sense.

Yes, make a gauge while you are at it. Although I don't ever use my gauge now because after doing the calibration procedure twice I now have a calibrated eyeball

[Radomir]

I'd do it in the EIS instead of the screen.. you have to calculate new SF and offset, but that's easy by going through the worksheet. You can then fine tune by changing the offset slightly and have accurate readings.

IIRC you'll have to switch the sensing before recording the raw numbers, though..

[RV6airplanePilot]

Jerry, you have mentioned parts of 2 separate steps, sounds like you may have mixed them together. The 1st part is to determine the Scale Factor which measures the range between empty and full. Using 100 is practical reference value which is used in a calculation when you find the EIS readings when the tank is full vs empty. Sandy has provided a worksheet that guides you thru this 1st process. There is little point in doing the incremental addition of gas prior to finishing her worksheet and getting your secondary (hopefully final) Scale Factor. the Offset factor is used to move the scale so that your empty condition gives a reading on the EIS close to zero. When that is done you can leave the EIS on in normal mode, on the fuel guage screen and do the incremental filling and make a table with 1 column for the actual gas in the tank and a 2nd column listing the EIS readings. Now you can open the table in the EFIS and 1 column is the EIS reading and the other column is what you want the EFIS to show; it is a translation table. I don't recall which column is on the left in the EFIS, but when you know the approach it is pretty easy to understand the headings. When I am flying I look at the fuel used and compare to the EFIS reading. I can make or tweak my EFIS table in level flight in smooth air.
Dale
RV6a GRT HX
former user of Sport SX

[RV6airplanePilot]

[quote=RV8iator;616735] Here's where I get lost. What reading goes is what box? Probe/Actual..
QUOTE]

Think of "Probe" as the value shown on the EIS for that tank, "Actual" is the amount of fuel in the tank. This all refers to how to use the "table" in the GRT EFIS.
Dale
RV6a GRT HX

[RV8iator]

I think. I'll have to get a worksheet from Sandy.

[Mike S]

Originally Posted by RV6airplanePilot

J The 1st part is to determine the Scale Factor which measures the range between empty and full. Using 100 is practical reference value which is used in a calculation when you find the EIS readings when the tank is full vs empty. Sandy has provided a worksheet that guides you thru this 1st process. There is little point in doing the incremental addition of gas prior to finishing her worksheet and getting your secondary (hopefully final) Scale Factor. the Offset factor is used to move the scale so that your empty condition gives a reading on the EIS close to zero.
Dale
RV6a GRT HX
former user of Sport SX

Dale, this is the first time I have ever seen anyone explain this.

It actually makes a lot of sense the way you put it.

I am actually frightened to think I might have understood all of it

[Capflyer]

Widget and all, if you have not yet joined, be sure to join up with the GRT yahoo group. http://groups.yahoo.com/group/GRT_EFIS/ It is pretty active with lots of info and files. I will upload to it a simple Excel spreadsheet where you can put in your empty fuel reading, full fuel reading, and desired reading when full. This way you don't have to go through the long formula that GRT supplies to calibrate the fuel quantity readings. The file name is: EIS Fuel Float Formula. Hope this helps.

[RV8iator]

Thanks for the file Mike. Now all I have to do is drain and fill. I'll let everyone know if "even Widget can do it".