Fuel tank calibration problems

[airnet]

Hi!

I did fuel calibration on Dynamic aircraft. Each fuel tank holds 63 liter. Because of the geometry of fuel tank (extremely long optional tank) fuel and position of fuel sensor change in fuel quantity was not detected in first 5 liters, from 30 to 35 liters (low vertical high of fuel in comparison to horizontal because of long in wing tank) and in last 8 liters. I have always confirmed fuel was added even not being detected
At the end of the process Skyview said, that calibration was not successful and if I want to save the results. I confirmed.
I am now getting correct level of fuel indication on EMS, but on the top of the indication there is CAL! and no quantity in liters. Please explain how to properly do the procedure in a case where fuel increase will not be detected during all phases of calibration.
Thanks, Iztok Š.

 

[schristo]

a couple of ideas for you... if you have float sensors the float arm at the rheostat has mechanical resistance that adds drag and small changes in fuel quantity may not be enough to move the float... try tapping on the sensor, or wing skin near the sensor... with the engine on there is enough vibration to get the float moving correctly.

i did the initial 2 gallon calibration to get values in the system but went back and did it again at 1 gallon intervals and manually recorded the values to use in a spreadsheet... in the spreadsheet i interpolated the data and picked points near the end of the range where the tank geometry cuts into the sensor range... with the data processed i modified the calibration data in skyview where you can edit both gallons and resistance.

 

[airnet]

Thank you for your answer Stephen. I can do the interpolation and modify values accordingly, but need to know, what changes CAL! quantity indication to liters. Does every value in l. need to have different resistance value?
There is no way that sensor will read first 5 liters. Arm is too long and quantity too little to pick up the change.
Same for last 5 (8) liters.
BR, Iztok

 

[schristo]

for mine the display shows 16+ for the left tank and 17+ for the right tank for values above the float due to wing geometry and float position... you should probably make sure that all of the calibration slots have data in them even if it is the same... for the low end use the first resistance that you can read reliably... for point 1 use 5 liters with the resistance value, the next point can be 6, 7, 8, whatever liters... the spacing does not have to be the same point to point.

 

[mmarien]

I did the calibration twice. The battery went dead the first time. The second time nothing was happening so after the first forty litres (ten at a time) I shook the plane to get the sensors to move and then waited for them to settle down. Seem to work except the first forty litres don't register. I'll have to do it again when I get a chance.

Topping up seems to agree fairly closely with the litres remaining.

Is there a way to fill in the first three measurements that are missing?

 

[airnet]

Hi guys!

I have solved the problem. Stephens idea to mess (edit) with results of calibration helped. I went threw them and noticed that there was V increase where there should be decrease. It looks like there is (correct) logic behind that results should have linear rise or fall. Once I have corrected this fuel quantity is shown. I plan to do calibration once again in future with shaking aircraft a little and then waiting for the fuel to comedown. I want to get proper missing values. Thanks for all your help, till next problem. Iztok S.