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  #1  
Old 09-13-2021, 04:40 PM
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papamike papamike is offline
 
Join Date: Nov 2009
Location: McKinney, TX
Posts: 122
Unhappy Problem with Dynon Skyview and Van's floats when calibrating

Hi,

I'm about ready for inspection and first flight.
I have a flop tube in the right tank, so the float got moved to the second tank bay out. I'm trying to fill the tank and calibrate using Skyview. The left tank went great.
Basically, the right tank is not getting any changing readings up to full. There is a very slight change about midway through (10-12 gallons), but even nothing different after that. I am getting readings, so I don't believe wiring is an issue.
I went through the entire process regardless. Dynon asked if I wanted to keep the settings, and I said yes. But the right tank still shows the Cal prompt.
Any ideas before I pull the tank?

I'm even thinking about taking the flop tube out and putting it all back the way it is on the left side...
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  #2  
Old 09-13-2021, 08:03 PM
Jimzim Jimzim is offline
 
Join Date: Mar 2009
Location: Arvada, CO
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Pete,
I probably wouldn’t pull the tank as an initial step.
Could it be a stuck float in your right tank?
I personally have had to replace one new Van’s float and remove and tweak the tab pressure that allows the float to move, on the other one. I was able to do that through the access hole in the inboard tank panel, even in my right tank with a flop tube set up like yours.
Both of those were new from Van’s and passed the battery test before installation.
Those floats leave a lot to be desired.
After all that and 3 recalibrations through my Skyview, my gauges now read within 2 to 3 gallons per side, at best.
Needless to say, I absolutely do not count on these for fuel quantity beyond a rough guesstimate.
My Red cube has proven very accurate, and my wrist watch is even more dependable.
Not sure why your Skyview seems stuck in CAL mode, I did not see anything like that.
Good luck, Jim
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  #3  
Old 09-13-2021, 08:32 PM
John Tierney John Tierney is offline
 
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Location: Vonore, TN
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If you don't have a dedicated ground to a bolt/screw on the tank you could try a temporary ground wire and see if that helps. I put one under a screw at the sender access plate.
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  #4  
Old 09-14-2021, 08:26 AM
ty1295 ty1295 is offline
 
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Location: Jeffersonville, IN
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I agree the floats are not the greatest. Mine are somewhat ok to 11/12 gallon range but cannot read anything above that. The left tank "sticks" at times also. Not sure if proseal maybe go on it, or its just flakey.

Do you have a spare float you could wire to skyview and just manually try to verify wiring all the way to wing, and isolate it to just a float issue?
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  #5  
Old 09-14-2021, 09:54 AM
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wcalvert wcalvert is offline
 
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I'll chime in and say my floats (mis) behave the same way. Have done the cal twice, was convinced one float was stuck so whacked the bottom of the tank with my hand after each fuel add ... marginal improvement and sort of demonstrated that one was sticking.

The floats will behave better once the aircraft is bouncing around on the ground or in flight, but as Jim said, they are a rough way to estimate the fuel below about half. Above half and they just read 14+. About accurate enough to know when to switch tanks! Rest is totalizator, clock and visual check.

If you consider the geometry of the tank with an eye to dihedral, the inboard section will appear full while the tank is only partly filled. Limits of the design (my ride at work has 13 sensors in each wing tank! to combat that problem)

I have run a tank pretty low and will say that in level flight they are pretty accurate towards the bottom. Also keep in mind that if you cal a tailwheel with the tail down, it will differ from your reading in flight (pretty obvious).

Good luck!
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  #6  
Old 10-13-2021, 04:12 PM
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papamike papamike is offline
 
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Well, a quick update...

I have some downtime because my test pilot/instructor is on vacation.

I have replaced the float. No help.
I ran a wire from the float to pin 21 on the Dynon EMS, essentially bypassing my wiring. No help.
Voltage reads good, it just doesn't change.
I pulled the tank again today. The float resistance and voltage changes when I move the arm, as it should. I decided that I'm going to remove the flop tube, and move the sender to the inboard rib of the tank as is standard. I'm tired of experimenting, because of the work involved in draining the tank, trying a calibration, draining, etc, etc.

Got to be ready to continue (or should I say start) phase 1...
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  #7  
Old 10-13-2021, 04:20 PM
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airguy airguy is offline
 
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Location: Garden City, Tx
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Quote:
Originally Posted by papamike View Post
Well, a quick update...

I have some downtime because my test pilot/instructor is on vacation.

I have replaced the float. No help.
I ran a wire from the float to pin 21 on the Dynon EMS, essentially bypassing my wiring. No help.
Voltage reads good, it just doesn't change.
I pulled the tank again today. The float resistance and voltage changes when I move the arm, as it should. I decided that I'm going to remove the flop tube, and move the sender to the inboard rib of the tank as is standard. I'm tired of experimenting, because of the work involved in draining the tank, trying a calibration, draining, etc, etc.

Got to be ready to continue (or should I say start) phase 1...
The sender is nothing but a variable resistor, from about 20 to 220 ohms. Put a potentiometer in it's place and turn it up and down by hand, see if the panel reading changes. If it does not change, then you have a wiring or configuration problem, not a sender problem.
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  #8  
Old 10-13-2021, 06:44 PM
turbosaaber turbosaaber is offline
 
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Location: boynton beach fl
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Default questions.

Mine shows full up to a level of 12 on one side and 14 on the other. 14 with flop tube and 12 on the other. I was told and agree this does not matter as when it get the fuel quantity goes below then it registers the correct level. It did take me 4 tries to get the fuel used calibration correct which is nothing more than adjusting the correct formula. I have a red cube and flop on one side and normal pickup on the other. Do you get fuel quantity after or below your 12 indicator? I know we have 21g tanks but the fuel quantity will only show 12-14 due to the float travel.
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  #9  
Old 10-14-2021, 06:33 AM
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riseric riseric is offline
 
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The float being at the lowest area of the tank (think diedhral angle), it will be at its most elevated point (ie:touching the top skin) when the tank is about 3/4 full.
During my calibration, after 16 gallons, after each 2 gallons added there was no change in the measured fuel level as the float was at its upper limit.
So I have 15+ as indication on the fuel levels when tanks are 3/4 full or more.
In your setup, the float being higher from the start, would it measure 0 until there's a few gallons in there before starting to register...???
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  #10  
Old 10-14-2021, 08:03 AM
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Snowflake Snowflake is offline
 
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Have you checked that the float actually floats?
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