J

jffarrell

I'm New Here
Just purchased a 2008 RV9A and in the process of recalibrating the fuel tanks. Fuel quantity is indicated on an Advanced AF4500. Completed the calibration procedure on both tanks at 2 gallon intervals. On each tank the highest reading I could get was 10 gallons. Checked the resistance of Vans guages and they are 240 ohms when empty and 30 ohms after I have put 10 gallons in the tank, so they are working correctly.

I know the wing dihedral causes the guage to top out before the tank is actually full. For example, I can put 5 gallons in before the fuel reaches the bottom of the tank at the fill hole.

My specific question is, on the RV9A, how much should the guage/EFIS register when the fuel tank is full. It seems like 10 gallons may be a little low for an 18 gallon tank. If it should be more, it looks like my only option would be to pull the guages out and check the bend point in the float rod to make sure the float is not stopping before it hits the top of the tank.

Thanks,

Jim
 
In my 6A, the stock gauge stops going up somewhere around 15 gallons. I had a similar problem as you with ONE tank on a 7A. I did not build that plane or know exactly how the sender works, but my guess with the 7A is that there was a problem with the sender.
 
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Another option is to not worry about it. Do a good job of calibrating the fuel totalizer system.

Fly an hour or so on one tank. You should be near the level where the fuel quantity indicator is reliable on that tank. You know anyway from total fuel burn what is left on that tank even if the level is above ten gallons.

Then switch to the other tank and run about the same time.

You will know at all times how much fuel you have from the total used/total remaining.

Operationally it is not a big problem. You could even say it is not a problem at all.

On cross countries I burn ten gallons from the left side then some amount on the right depending upon the next fuel stop. My stock fuel gauges are probably less accurate than your system will be below ten gallons. Is it a safety issue knowing whether you have 12 or 14 gallons on a given side?

Tis your choice. If it bothers you then you can try to change it. Or realize that operationally you can still manage your fuel with more than adequate precision.
 
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Ron Lee said:
Operationally it is not a big problem. You could even say it is not a problem at all.
Click to expand...

Right up until you have a fuel loss for any reason other than burning it through the engine. Tank leak, piping leak, loose cap in flight - all these will ruin your day in a hurry if you are relying solely on the totalizer. This is why the FAA requires a fuel gauge for each tank. Granted, they don't have to register full when full, only empty when empty, but they are still required to be functional.

I went with the capacitive senders in mine to solve this problem.
 
Greg, each tank indicator is functional at and below ten gallons. Any of the scenarios you listed could be caught before it became a safety issue.
 
Jim,

My Dynon EMS fuel level indicators top out at 10.5 gallons on my 9A. I was very careful installing the senders to make sure I got a full swing out of the floats.
 
fuel levels

My right tank toped out at 11.5, and the left at 14 gal. The readings are fairly accurate when the fuel starts to indicate use on the gauges. When the gauges indicate 5 or so gal in either tank, filling it up takes right at 13 +- 1 gals. Better accuracy at the top end would be nice, but it is a livable situation. They are just resistance gauges and I am not going to spend the money or time on a capacitance conversion.
 
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