Fuel Flow programming

[johns4689]

I'm flying a RV-12 with the Rotax 912. I did not have the tag on my FloScan Transducer. I have the K Value set at 30000. My D10 is showing 9.4 GPH at cruise and I know
that is not right. I have a few questions: As I look at page 3-10 of the install guide I see a Restrictor T for the 912. How does this get connected back to the tank? And on page 5-14 it talkes aboutthe RETRN FLOW setting. What is this? Do I need the Restrictor T since I have a return line back to the tank after the mechanical fuel pump?

 

[dynonsupport]

The RV-12 uses just a single fuel flow sensor, with a K-factor that is usually lower than what it would normally be. The return flow is a "fake" second fuel flow sensor simulated by the Dynon to mimic a return flow sensor (which ideally gets about constant flow through it). I can't speak to the plumbing setup on the RV-12 - you'll need to ask Vans for the official way to build it. They should also have the return flow setting available for you (I believe, but am not sure, that it should already be set to a non-zero number if you bought your RV-12 D180 from Vans)

 

[johns4689]

I built the RV-12 as a EAB so I don't have any settings from VANs. I use the D100 EFIS and a D10 EMS. With a high fuel flow reading which way should I adjust the K factor (UP or DOWN)? I'm at 30000 now.

 

[dynonsupport]

Up. You're telling it how many pulses are in a gallon with the K-factor, basically. Moving it up requires more flow to equal a gallon.

 

[dynonsupport]

Actually, in a D10 EMS, there is another setting you need to make to create a "virtual" return line. Van's sets this when they sell them, so we don't know what numbers they use here. You'll need to find someone with a RV-12 with a D10, D120, or D180 and ask what they are using, or call Van's and ask them what they use when they ship an SLSA kit.

 

[funflying]

I too have an RV12 and need to know how to get to the screen where the K factor/pulses can be adjusted with my Skyview.

 

[Dynon]

SETUP MENU > HARDWARE CALIBRATION > EMS CALIBRATION > FUEL FLOW CALIBRATION

 

[Edwardoc]

I have never satisfactorily calibrated my fuel flow. When I do it, my intent is to fill tanks, go fly for an hour and refill to same level. My question is should the hour be from start to shut down which would include some taxi time etc, or what. Does it make any difference about leaning etc. If someone has a method to accurately accomplish this calibration please let me know. When at cruise with an IO-360 and 8500', I can lean it to 6.5 GPH before EGTs peak and that is not accurate.

 

[dynonsupport]

You really need to do this over about 100 gallons, not just 5-10. About 3 full tanks in an RV. Doing it over a small amount means just a tenth or two of inaccuracy when filling the tanks makes a big difference.

Fill the tanks completely, then write down the fuel used in the EMS vs. the fuel pump. Do this until you have about 100 gallons used.

Then use the formula on page 7-57 of the install guide to adjust your flow.

If you are WAY off, you may have started with the wrong numbers. The red cube flow sender is 68,000 and the gray floscan is 40,000.