Fuel Sight Gauge Calibration

[Nev]

It occurred to me that our main tank fuel sight gauges should all mostly be calibrated about the same. Perhaps tire size might affect it somewhat, and the sight gauge length and angles might vary, but the placard levels should show a similar pattern.

I originally did mine prior to its first flight. I'm currently playing around with 3d printing some editable placards. The photos below show a first attempt at a 3d printed one, and how mine are currently calibrated.

I'm interested to see how others have calibrated their sight gauges - if you have a photo of yours please post it below.

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[jaredyates]

Hi Nev, I made these about 6 months ago and they have been working great. I doubt there is much crossover on the calibration but would be interested to see real data. Screenshot_20250924-152530.png

[Nev]

I love how simple you've kept it !

[Battson]

I found that the tires, moving from 800's (around 20") to 31" ABWs made a considerable difference. Even though it's only a few inches difference at the axel, given the softness of the ABWs at low pressure. On the ground in three-point attitude, there was a obvious error.

Naturally the gauges are still good in flight

[alaskabearhawk]

Here is a photo of my sight gage. Very simple

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[Richard E]

Simple piece of unplasticized pvc tubing. The float ball isn't really needed (especially after it has sunk!)
20250930_131537.jpg

[Nev]

Interesting caution placard there about not selecting Both.

[Richard E]

I thought twice about putting that pic up because I knew that you would notice it! When we first tested the fuel flow we found an airlock in the system before we got more than 20 liters a side. Hence the placard. Having since suffered a fuel failure on a single tank with only 20 liters a side I have reached the conclusion that the placard should say the opposite - ALWAYS USE BOTH WHEN FUEL IS LOW. In fact, I fly on BOTH at all times and wouldn't want to use either left or right, in line with your findings elsewhere on this forum.

I ought to remove the placard and amend the POH but doing that requires CAA approval which is just toooooo hard!