Fuel gauge shows 15 gallons with 50 gallons tanks

[Localizer]

Hello everyone,
Here is something I'm curious about. I have 50 gallons tanks. When they are filled up to the caps, G1000 shows that i have between 15 and 20 gallons. The needles sit on 15, they don't go over 20 which, I think they should do.
What is this? Where do I start troubleshooting?
thanks,
Yuri

[mdieter]

Hmmm, ours go to just under 25 gallons when full. There is a 'null region' between 15 and 20 that displays as 15 gallons. Maybe your G1000 isn't configured for the long range tanks? If it was hardware I would think one tank would show 25 and the 'bad' side show 15.

[carym]

There are 3 tanks in each wing. There is a sensor in the outer tank and a senor in the inner tank. As the outer tank's fuel is used the G1000 will show a continual decrease in fuel. Once the outer tank is empty, the G1000 will read 17 gal (or perhaps in some planes like Mark stated 15 gal) while fuel is still being used from the middle tank. When fuel is starting to be used from the inner tank the G1000 will show less than the 17 gal. My suspicion is that you have something wrong with the outer tank fuel sensors, perhaps bad sensors or bad connections or even possibly the G1000 is not configured to see the outer sensors.

[Rick]

Yuri,

When you look at the fuel gauges on the MFD G1000 engine page, do they show 20 or 25 gal as the upper limit? Did you do any G1000 software upgrades lately? The "long-range tanks" are an option you must select whenever the G1000 software is installed or updated. I would bet that someone forgot to select that "option" during the last software upgrade, so your G1000 thinks you only have 20 gallons in each wing. If this is the case, your gauges will show 20 gal as the upper limit, and the G1000 will ignore the probes in the 2 outer tanks. Look at your gauges, that will tell you for sure. IF the gauges show 25 gal as the max, then you have some other problem, but I would bet they only show 20 as the max.

[CFIDave]

...the G1000 will read 17 gal (or perhaps in some planes like Mark stated 15 gal) while fuel is still being used from the middle tank. When fuel is starting to be used from the inner tank the G1000 will show less than the 17 gal.

The DA40 and DA42 are slightly different. The DA42 gauges appear to show continuous measurement of the fuel level as fuel is consumed, but as Cary mentioned, the DA42 level gets "stuck" at 17 gallons for awhile. In contrast, the DA40 has a "dead spot" on the MFD gauge where it simply doesn't indicate anything between 15-20 gallons.

However in both aircraft types this is caused by a similar fuel sensor design: there are separate capacitive fuel sensor rods for the outermost 5 gallon aluminum tank (for DA40s with extended/long range fuel tanks) vs. the middle tank. Thus when an indicator doesn't exceed 15 gallons in a DA40, it likely means that the system isn't able to get a reading from the capacitive rod fuel probe within the outermost (extended range) tank.

Assuming the G1000 is properly configured for extended range tanks, you may be able to check and test the probe wiring via an underwing access panel. If it's not a bad connection, you might have to remove the wing and slide the fuel tanks (located between the carbon fiber wing spars) out to replace the fuel level probe -- attached to the inboard end of the outermost fuel tank. See the DA40 AMM Chapter 28-40 http://support.diamond-air.at/da40-180_ ... 73ab0.html

[Antoine]

If BOTH sides are off, I have difficulty accepting that the sensors failed simultaneously.

Another diagnostics direction:
The G1000 has a fuel probe calibration procedure.
Once correctly calibrated it should give very accurate fuel quantity measurement except in the "dead zone" mentioned above. Mine (SN 40.807) has been very reliable in this respect.
It may be that your fuel probes were badly calibrated or the G1000 lost its calibration - did you have someone upgrade the software or something?
It happened to a friend of mine on a brand new DA40.

[Localizer]

Hi guys!
Thanks for all replies and thoughts.
I finally was able to get to the plane today and talked to avionics shop.
It is a software issue. I had some weird things going on with EIS (it was x-ing out) and software was reloaded. This is when a wrong choice of tanks was selected.
The gauges show 25 gallons each.
Next week I will visit avionics shop andthey will have it fixed.
Yuri