Onex fuel sight level guage

[Hap Hazard]

Been moseying through the Onex drawings.
How easy is it to fit the fuel sight level gauge option to the tank that’s featured in the drawings? As I haven’t had the glare shield off my Onex yet, I am not sure what standard plumbing comes with the tank. The drawings show a couple of 1/8 thread plugs, one at the top rear and one at the bottom. I assume this is where the sight tube gets plumbed into….
Regards,
HH

[JohnH]

Over the last few years I have unsuccessfully tried to calibrate my Onex MGL Xtreme fuel gauge system and it seems that working with 3 different technologies (Sonex, MGL and Princeton) is difficult, plus Princeton is no longer in business. So I have now decided to also install some sort of fuel level sight glass system and would appreciate also hearing from anyone who has done it, with particular reference to the plumbing and does the fuel tank require drilling and what fittings (...Oops fittings?) work best and what material and size should the sight glass be.
Many thanks
JohnH

[13brv3]

I haven't seen any sight tubes, and the last thing I'd want to do personally is add a number of potential leaks in the cockpit. I have heard of people using small cameras behind the panel to view the level on the tank, or even cut a vertical slot in the panel to see it directly. You'd probably have to provide a light source maybe attached to the tank somewhere.

As for Princeton sensors, I had fits with mine until we realized that the new company who took over manufacturing them neglected to leave a ground wire attachment. Once I made a clamp to provide ground, it's worked well with my Dynon.

[T41pilot]

For those still interested in Princeton fuel level senders, Red Avionics bought the rights and is producing their type of hardware.

[Bryan Cotton]

I have a fuel camera. Turns on with a switch, and a tank light turns on at the same time. It works ok but there is probably a more optimum way to light the tank so it is not too dark and not washed out.
https://youtube.com/shorts/rAUjAJ73rN0