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Dynon Skyview fuel quantity

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  • Dynon Skyview fuel quantity

    my new to me 2013 Calidus has. Dynon Skyview screen for the PFD/map/engine functions with synthetic vision. All very cool, and now that the 912 ULS is running well, very fun to fly. The fuel quantity always reads 18+ gal on startup no matter the actual fuel on board. The Dynon tech support guy wants to know the type/model of the fuel sensor that AutoGyro installs in the tank before shipping?? I know the sensor worked when I flew the plane prior to purchase in Jan 2017, but did not work when the gyro got delivered to me months later. I'm several states away from the gyro at the moment, but we will be reunited in a few days. If you have a Dynon savvy avionics person near San Antonio Texas let me know. Thanks Ray

  • #2
    I had a Skyview on my last gyro. You have to go through a fuel calibration process. Basically it's a methodical way to add a liter at a time and set the volume on the digital gauge.

    I don't think the sensor type will change the process. If you still need it I'd call Terri at AutoGyro USA. I'm sure they'd be able to help.


    • #3
      The tanks hold ~20 gallons but the sender can only float up to the 18-gallon level.
      Anything above that just reports 18+ until the sender gets into range.
      When the sender hits bottom, the gauge will report zero even though you may still have a half gallon of unreported fuel remaining.
      When it say zero, you better hope you are on very short final! There may only be a few minutes of fuel remaining.

      The sender is at Zero ohms when empty and 90 Ohms when full.
      Anything over 90ohms will just display as 18+ gallons.

      A disconnected wire is infinite ohms, which will also display 18+ Gallons.
      Put a meter on the fuel sender; You should see something other than zero if there is fuel in the tank.
      Short out the connector going to the Dynon (Zero Ohms); it should display an empty tank if the wiring is good.

      If it worked at one time, I would look for a bad connection before messing up the calibration table.
      You can look at the calibration file in the edit menu to confirm that all the values in the table are reasonable and not 18.


      • #4
        True, could be a bad sensor or connection. Also keep in mind that if you use AvGas or a mix, you're readings will be really off. Whatever fuel used during calibration is the only fuel that will read actually. Even going from fuel with ethanol to fuel without will throw it offf.


        • #5
          Where do I look to find out how to do the calibration process?


          • #6
            Try this link for Skyview manuals

            PRA member 41204
            PRA Chapter 16


            • #7
              I reviewed 7-59 to 7-61 in the installation manual, but it starts by assuming I know whether I have a resistive or capacitive sensor? A loose wire would be great to find. I tightened the plug in on the Dynon end, but don't see where the connection is on the tank end? Ray


              • #8
                The sender in the Calidus is on the top of the Left Fuel Tank, hidden almost directly under the Fuel Fill Cap, an inch aft of the firewall.
                It is a Resistive Float type sender.
                You will need to remove the cowls to have any hope of seeing it.
                A heavy looking Black wire should lead you to a Blue Plug with only 2 of the 6 pins installed.
                - - - - -

                If you actually need to recalibrate, keep in mind that measuring weight accurately is much easire than measuring volume.

                You will need to empty the tanks so at least 4, 5gal. containers will be needed.

                Accurately measure the EMPTY weight of one of the 5 gallon cans. let's assume it weighs 2.5lbs.
                Now take that can to your local gas station and fill close to full. Note the EXACT amount of gas in the can. Let's assume it took 5.170 gallons.
                Measure the weight of the Full Can. let's assume it weighs 34.35lbs.
                Subtract the weight of the can and divide by the gallons will yield the weight of one gallon of gas.

                34.35lbs-2.5lbs = 31.85lbs of gas
                31.85lbs/ 5.170Gal = 6.16 lbs per gallon.

                If your calibration calls for 1.75 gallons per pour...
                1.75gal * 6.16 lbs per gal + the 2.5 lb can = 13.28lbs.

                Add or remove gas from your reference can until it weights exactly 13.28lbs.
                When you pour this into the tenk you will be adding 1.75 gallons, easily within an ounce.

                Yes! It is tedious but you will sleep well knowing it is correct!


                Last edited by Uncle Willie; 06-18-2017, 01:41 PM.


                • #9
                  Bill, thanks for all the info, I'll get to the airport this week to try. I have several fuel cans and a scale.


                  • #10
                    Good news. I removed the cowls and checked the sensor connection. When I turned the Dynon back on, it correctly read 10 gal. I decided to drain all the fuel and recalibrate following the instructions. Initially I made an error and selected "left tank" and as I filled the tank two gallons at a time as instructed, between each fill the Dynon would report no change in voltage and ask had I really added the fuel. I then realized I should have selected "main tank". When I restarted the Dynon it recognized the 8.0 gallons in the tank as the fuel level, and as I added two gallons at a time it recognized the proper amount of increase until full (this was not a recalibration just adding fuel). So as of this moment, it works!! I do need to recalibrate the fuel flow transducer "K" factor, but if the tank shows the proper amount I feel safer. Thanks for all the help, which as a newbie, I really needed. Ray


                    • #11
                      With the Dynon reading the correct fuel quantity, my next project was to adjust the "K" factor to reflect the fuel flow more accurately. The Dynon only lets you adjust the number up to 130,000. As you raise the number of pulses, that is reflected by a decreased fuel flow shown on the Dynon. It was set at 95,000 pulses and read that I was burning 5.5 gal/hr at 4800 RPMs. When refilling the tanks, my actual fuel flow was closer to 4 gal/hr. Increasing the pulse number on the Dynon to 130,000 now shows a fuel flow of 4.4 gal/hr.....closer but still too high based on my actual fuel usage. The Dynon tech suggests that my fuel return (unburned fuel returned to the tank) transducer my be adjusted wrong? Does that sound right? The good news is that a check of my log book shows I've gotten to fly the gyro 15 of the past 17 days! I fly early before the Texas heat cooks my enclosed canopy. Ray