Fuel tank calibration

Garry626

I love flying!
Joined
Jun 22, 2014
Messages
3
Hi,
We have been trying to correctly calibrate the fuel tanks on our RV 7A following the calibration process as per the Dynon wizard. The tanks have the Vans supplied float sensors fitted. We have completed the process on 5 occasions on the right tank but have not achieved a successful outcome, the left tanks calibrated as expected. Looking at the voltage results there appears to be an issue at points 2 & 3 where the voltage first went up and then remained the same before returning to normal at point 4 onwards. Both tanks were filled to the full 80 litre capacity. :-/

Left Tank
Point. Volts. Value
1. 2.76 0.00
2. 2.40 10.00
3. 2.10 20.00
4. 1.84 30.00
5. 1.62 40.00
6. 1.46 50.00
7. 1.09 60.00

Right Tank
Point. Volts. Value
1. 2.13 0.00
2. 2.29 10.00
3. 2.29 20.00
4. 2.05 30.00
5. 1.70 40.00
6. 1.46 50.00
7. 0.90 60.00
 

Dynon

Dynon Staff
Staff member
Joined
Jan 14, 2013
Messages
14,217
Location
Woodinville, WA
For some reason, SkyView isn't seeing a sensor change between those two points. It's likely physical - perhaps some stickiness in the sensor, preventing movement, or possibly a defect in it that is causing some movement to not translate into a resistance change.
 

Garry626

I love flying!
Joined
Jun 22, 2014
Messages
3
Thanks Dynon for the reply,
Next question there is an edit facility in the calibration section, can we manually change the values for the erroneous points 2 & 3 too correct the problem or use data from the left tank calibration. Prior to completing this recalibration I did a data dowload to a usb for another issue we are trying to resolve which I have forwarded to you, will the original calibration settings be contained in that download data, if so how do I locate them.


Garry
 

Dynon

Dynon Staff
Staff member
Joined
Jan 14, 2013
Messages
14,217
Location
Woodinville, WA
If you go back into the calibration menu there will be an EDIT button once you have the calibration stored. So yes, you can fudge it and move the points. But be very careful. You can end up skewing things such that you think you have more fuel than you really do. I just noticed that your voltage raises and then falls between 0 and 30 gallons. Knowing what is "correct" is going to be hard here. And if the sensor is reliably outputting these values, no calibration is ever going to be able to work well.
 

Garry626

I love flying!
Joined
Jun 22, 2014
Messages
3
Update on the process
Today we revisited the hangar and I am pleased to say successfully resolved the issue. It was clear from the many failed attempts that the float sender in the right tank was sticking during the calibration procedure and with the tank empty the sender appeared to be stuck at the halfway position, shaking the wings did not appear to move the float position or register any change on the voltage shown. What did register a change was tapping the underneath of the fuel tank in the area of the sender gauge until the empty voltage stabilised at a value similar to that recorded during the calibration of the left tank. Following every 10 litre fill we completed the same tapping process to stabilise the voltage which resulted in a successful calibration.
Whilst we will always mindful that the sender may stick during operation the several failed calibration attempts have assisted in the production of an accurate dip stick. The Dynon is displaying accurately the total fuel in the tanks and early indications seem to show the tanks read outs reducing inline with fuel removed.
A frustrating few days but it may be that our learning may be of use to others during this procedure. :)
 

dynonsupport

Dynon Technical Support
Staff member
Joined
Mar 23, 2005
Messages
13,226
Thank you for reporting back on your results. That is very helpful to other users.
 
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