Belite fuel level.

[Corby202]

I recently fitted a Belite fuel level transducer to my plane. Although it works fine and appears reasonably accurate on the ground (when the plane is level) it reads low in the air and is not constant particularly when the air is rough.
Anyone else who is using one of these Belite transducers find the same thing??
Thanks

[Sonex1517]

Hi

I have the BeLite fuel transducer and gauge. I have, so far, been unable to get it to read accurately.

At first it showed my fuel tank emptying very quickly after takeoff, when it wasn't. I called the company and got advice from the owner - he thought it was the fuel vent position. Following his advice I adjusted the fuel vent to put more pressure into it.

Now the fuel gauge reads full no matter how long I fly.

I am still hoping to get it to work.


Robbie Culver
Sonex 1517
Chicagoland
N1517S

[DCASonex]

Robbie,

Thanks for that info on the Belite fuel level gauge. I was thinking of that option when having some problems with my GRT / Princeton capacitive type fuel level sensor. I have my vent(s) configured to provide a bit of ram air pressure in the tank, which evidently would have affected the Belite's reading, and would not have wanted to do away with that positive pressure to fuel pump and Bing carb. Fortunately traced my problem to vibration affecting the control unit of the GRT / Princeton unit and since relocating it have had no further problems.

David A. Sonex TD with CAMit 3300

[Klimek]

I have the Belite system in my ONEX and was easy to calibrate once the proper gauge was installed, however, it is in need of calibration, again.
I burn 100 LL and found that for some reason it just starts staying on full for long periods of time. After flying an hour or so it is still on full.
After two hours the gauge indicates 80%- 90%....My fuel burn in cruise is 4.5 gph and should indicate 40% +-.
I have my plane back at my shop to paint, add SONEX hyd. brakes, replace the windshield and rearrange the cockpit and will try one more time
to calibrate the Belite fuel level gauge and keep it calibrated.
Frank
ONEX 090

[Mike53]

I am beginning to be a bit concerned about my choice of purchasing the Belite probe and fuel gauge.
I have just installed it this week and have not calibrated it yet.
So far with three out of three reporting problems,I begin to wonder if it's such a great product after all.
Anyone out there with a good report card on the Belite?
Cheers,
Mike

[Sonex1517]

I have the Belite system in my ONEX and was easy to calibrate once the proper gauge was installed, however, it is in need of calibration, again.
I burn 100 LL and found that for some reason it just starts staying on full for long periods of time. After flying an hour or so it is still on full.
After two hours the gauge indicates 80%- 90%....My fuel burn in cruise is 4.5 gph and should indicate 40% +-.
I have my plane back at my shop to paint, add SONEX hyd. brakes, replace the windshield and rearrange the cockpit and will try one more time
to calibrate the Belite fuel level gauge and keep it calibrated.
Frank
ONEX 090

That is basically exactly what I see now.

Mike - to your point, I cannot steer you one way or another. I can say I am having difficulties but I will also say the company has been great to work with in regards to solving it. I have more work to do before I can definitely answer if it works.

Frank's post makes me think there may be something more to this than the fuel vent position.

[GordonTurner]

I have been interested in this fuel probe as well. One thing I noticed in their specs is a minimum fuel depth. If you have a tail dragged on the ground, it seems like the actual fuel depth between full and empty is going to change by let's say 12 inches. With the airplane in level flight, the fuel depth is only 6 inches (making up numbers for purpose of illustration). Is this contributing to the problem?

[kevinh]

I'm planning on using a Freescale sensor and doing something similar to the belite. I'm copying the work of Jim Butcher in this thread. The nice thing about his approach is that it also connects at the top of the tank and therefore should handle the ram air pressure.

[WaiexN143NM]

Hi all,
When using the Belite fuel sensor are u hooking it up to your dynon, mgl efis, etc, or are u using a belite fuel gauge , and if so, which one?

WaiexN143NM
Michael Radtke

[Corby202]

Doing a bit more research and the comments Robbie made I figured tank ventilation has to be the key. The belite transducer has to be very sensitive to be able to measure the change in weight/pressure of the fuel in our tanks so the slightest amount of + or - pressure will make a difference. With that in mind I flew again this morning but before I took off I pushed the flexible vent line I have back into the cowling thinking i could have been getting a slight neg pressure from the slipstream.
I made a note of the fuel with the dip stick and the Belite. With the fuselage level, I showed 40 litres on the panel. With the tailwheel down I showed 46 litres. Dipstick confirmed I had 40 litres.
Things did not change after I started the engine. Took off and with an extended climb out at 70 knots noticed the fuel reading was 46 litres. Flew at a constant 2900 rpm as I was also doing a fuel consumption test. (105 knots) .A couple of minutes after leveling off I got a reading of 40 litres. The air was not super smooth but not too bad. Further into the flight I saw the fuel quantity slowly come down. I then put the plane into a shallow dive, not wanting to touch the throttle, sitting on 130 knots the fuel level slowly dropped more but came up again when I levelled off. The fuel level reading was certainly not moving around like it had been on the previous flight.
Before descending to land I had a reading of 27 litres. After landing I checked the fuel reading again with the dip stick and the panel with the plane level I had 26 litres left.
So it does work. On my plane I have a drip tray around the tank neck. This has a drain fitting in the corner with a 1/2" drain line running out the bottom of the cowling. Also connected into this line I have the tank vent and the fuel pump line. I have a couple of extra fittings in this line going nowhere but are there just in case the bottom of the vent pipe was to get blocked. The Belite is connected via a RDAC unit to my MGL Ultra panel.
So the key is not to have ANY positive or negative air pressure in the fuel tank. The fuel surface area of our tanks is fairly high in relation to the size of the tank so it does not take much pressure to completely change the fuel reading in flight.
I also have a Belite slip indicator and at first glance the build quality of this and the fuel level level does not look great but they seem to work fine and the company is very helpful.