G3Xpert Question: Fuel Level Cal Scheme G3X Touch

Greetings,

I'm not far off from the smoke test on the panel and electrical redo!

I'm hoping to cal the fuel level sensors (resistive) by starting with one fuel tank completely empty and the other completely full. I'll mount a valve on the drain of the full one, and then transfer one gallon at a time from the full tank to the other. Is there any reason the G3X won't like this sequence of cal? I.e., one tank going up, the other down, switching between tanks as the calibration proceeds. Or must each data point be increasing fuel level from the previously entered point, and complete one tank before doing the other?

Thanks -

I always get the FBO fuel truck to put in 2 gals at a time. Floats reach there limit at about 16-18 gallons. I usually start at 0 then add 1 gal to see if I can get a change. I usually do. So I proceed with 1 gal increments for the first 3, then go 2 at a time after that. Starting full, then draining might work but seems cumbersome. The floats are very accurate in the G3X system. As long as the ball is centered!

It's been a couple of years since I did a fuel cal in the G3X, but as I recall, the two tanks were totally independent, and you calibrate one at a time - so it shouldn't make any difference what the other tank is doing while you're calibrating the other.

Living at airparks without fuel, I never have a fuel truck - so we do it from cans.. I'm going to remember Alex's trick!

Ironflight said:

It's been a couple of years since I did a fuel cal in the G3X, but as I recall, the two tanks were totally independent, and you calibrate one at a time - so it shouldn't make any difference what the other tank is doing while you're calibrating the other.

Living at airparks without fuel, I never have a fuel truck - so we do it from cans.. I'm going to remember Alex's trick!

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Paul, thanks. I will need to empty both tanks simultaneously in any case to weigh it, so I guess I'll just cal them on filling.

AlexPeterson said:

Paul, thanks. I will need to empty both tanks simultaneously in any case to weigh it, so I guess I'll just cal them on filling.

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Yes, you are on the right track here and Paul is correct that each side will have to be pulled up while in the calibration mode separately. The G-3X touch has the ability to know if you are in the flight Attitude or ground taxi configuration. I prefer to put the airframe in the flight attitude, level the wings, then block under the side you will be filling so it dose not tilt down as you fill.
You will get the hang of it as it does take a while to do the whole test and calibration. Do yourself a favor while you fill, take a ruler and a pad and write down the gallons and the level from the bottom of the tank while you fill. You can then put that on the last page of your "P.O.H.B." and have a good record to look at if you question the gages later on. Yah we used to fly old Cessna's with bad gages too. Hope this helps, Yours, R.E.A. III #80888

P.S. an old Curtus drain valve will help your drain of the tank easy. The kind with the pin through the valve to hold it in the open position. And car gas for sure will work and you can put it in the pick-up or car when finished.

The easiest way I've found to empty a tank is to disconnect the fuel line at the carb (or the corresponding place in a fuel injection system) and use the boost pump with the desired tank selected. Even the little Facet pump moves 40-45 GPH. If you place the airplane in the level flight attitude before pumping you will have the unusable fuel in the tank. That's the best place to start a calibration. Add a gallon of fuel (or a little more if you want) for "cushion", tell the G3X that's "zero" and start the process.

rvsxer said:

The easiest way I've found to empty a tank is to disconnect the fuel line at the carb (or the corresponding place in a fuel injection system) and use the boost pump with the desired tank selected. Even the little Facet pump moves 40-45 GPH. If you place the airplane in the level flight attitude before pumping you will have the unusable fuel in the tank. That's the best place to start a calibration. Add a gallon of fuel (or a little more if you want) for "cushion", tell the G3X that's "zero" and start the process.

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Mike, really good point about the unusable fuel, even though it is very small in the RVs. Thanks.