Erroneous fuel quantity shown in data log

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smoss
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Erroneous fuel quantity shown in data log

Post by smoss »

My plane has the 50 gallon long range tanks, and the G1000 correctly displays fuel quantity, showing 25 gallons a side when full (minus the tiny dead zone), but the data log has always shown non-matching and lower fuel quantities compared to actual. So when plane is topped off to 50 gallons, MFD correctly shows amount, but the data card records the fields 'gals-FQtyR and gals-FQtyL around 20.5 each usually. As the plane nears more empty, the real vs logged begin to line up pretty well. Anyone else notice this ever, or have a fix? The plane is obviously calibrated correctly for the long range tanks, but somehow the data log doesn't get that message.
Steve
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dmloftus
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Re: Erroneous fuel quantity shown in data log

Post by dmloftus »

My data logs show 25 on both sides when full. Is this a new issue with your logs? Have they ever indicated 25 each? Have you had your G1000 updated recently? Last time mine was updated, the avionics shop did not pick up the fact that I had 50-gallon tanks and the default was set to 20 & 20. The MFD showed tanks were full, but if you looked closely each gauge showed max value of 20. Once I returned to the shop they were able to quickly fix the setup data.
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Re: Erroneous fuel quantity shown in data log

Post by smoss »

The log has indicated like this for as long as I have had the plane, 13+ years. The MFD definitely shows the 25 gal labels, and the fuel totalizer matches precisely with the gauges starting at 50 gallons.
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Re: Erroneous fuel quantity shown in data log

Post by BkFlyer »

I would email Garmin support about it, or ask my avionics shop to investigate during next scheduled Avionics check. G1000 is antique tech, I wouldn’t assume that there is only 1 setting to control max fuel limit.
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Re: Erroneous fuel quantity shown in data log

Post by smoss »

I was thinking there may be a second setting somewhere, but then you'd think the max in the log would be 20, but mine usually starts at 20.5 or 21 ish.
Steve
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Re: Erroneous fuel quantity shown in data log

Post by smoss »

well, I figured out at least why it shows 21-ish when full. In the G1000 maint manuals, explaining the calibration process, it says this:
The G1000 in DA40 is set up at the factory to use 3 calibration points:
EMPTY (0.00 Gallons)
5 Gallons
FULL (15 Gallons for STD Range Tanks, 21 Gallons for Long Range Tanks)
NOTE
Although the total fuel quantity for long range tanks is 24 gallons usable fuel, the method
of fuel quantity processing in the DA40’s G1000 system only has a raw calibration total
of 21 gallons when both probes are at their ceilings. However, this does not affect the
actual display to the pilot, which correctly shows 24 gallons on the MFD.

So my log is showing the raw total of 21, not the converted total that shows on the actual fuel quantity displays. Still not sure why my log shows this value vs others' which show the actual 25, but easy enough for me to convert now that I understand it. I am also newly enlightened that the usable fuel quantity is actually only 24 gal, and hence the max on the display of 24. I always thought it just couldn't read the top gallon.
Steve
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