Is 912iS fuel flow widget still uncorrected?

jefish

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Reading the HDX installation manual, I came across this:

If you have not installed physical fuel flow sensors, the fuel flow information from 912 iS ECU used by the SkyView Fuel Computer can be adjusted if necessary: SETUP MENU > HARDWARE CALIBRATION > EMS CALIBRATION > FUEL FLOW CALIBRATION > PUL/GAL (C37 P14) > (value). The default value is 68000. Higher numbers will reduce reported fuel flow; lower numbers will increase reported fuel flow. For example, if the reported fuel flow is 10% low (determined by careful records of fuel fills and fuel used), set the value of C37 P14 to 61818 (68000 – 10%). Changing this value will not alter the displayed fuel flow; it will only alter the fuel used calculated by the SkyView Fuel Computer.

Is this still true? If so, it's kinda nuts. If the fuel computer can use the compensated pulses/gallon value to calculate the correct Total Fuel Used, why not use the compensated value in the displayed Fuel Flow widget? Also, which value does the HDX use to calculate "fuel remaining at destination"? The uncorrected fuel flow, or the compensated value?

Once verified and saved, the actual, normalized, corrected Fuel Flow value should be used everywhere, including pilot-facing widgets.
 
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Dynon

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It's still true. I suspect that we took a stance to display what the ECU is giving us directly for instrumentation, but still give adjustability if it wasn't adding up to the correct end result.
 

jefish

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So it's possible that the always visible bottom band could read a comfortable 3GPH, while the fuel computer, when invoked, could show the true burn of 6GPH?

I'm exaggerating, obviously, but the point is that the front-and-center-in-your-face-at-a-glance data could be very wrong. The corrected data is only available if the pilot purposely seeks it out.

I'd love to see the primary GPH values be based on the corrected values. If one wants to see what the ECU is sending, for troubleshooting purposes, that value can be shown elsewhere, like under EMS setup.
 

Dynon

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Sorry I didn't make that clear. Anywhere you see a fuel flow in GPH will reflect what the ECU is saying, verbatim. The computed things like fuel used, remaining, etc would reflect the adjustment.
 

jefish

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It was clear. I'm just still confused why the GPH display would not inherit and calculate fuel burn based on this adjusted value.
 

wout12

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May 28, 2021
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Mmm I have not figured out yet what is going on with my 80hp 912ul fuel burn as shown on the Dynon but it is so far off that I don't use it at all. I have to use the fuel tubes at the wing roots and even those are subject to the baffles holding back an unknown supply, so I always fly with tanks half full at the lowest.
 

sunfish

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Jan 21, 2013
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I agree with Dynons position. I have a 912 iS. It is vital to distinguish between reported values and calculated values on the instrument panel in order to understand and interpret the potential for error. For the 912 iS, Dynon displays the ECU CAN bus values as reported. I want it to stay that way because any engine indication anomaly arising must then, by definition, be a function of engine or ECU performance. I can rule out a display system failure. If Dynon recomputes the output, then I have to add the possibility that the Skyview is wrong.

As for fuel management, I still operate by the wooden dipstick and 20 litres per hour rule of thumb.
 
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