Ways not to make the sight gauges when using rigid PVC tubing

[Nev]

Regardless of what type of material used, it's a very good idea - and required in Canada - to put a restrictor in the system to reduce the flow should there be failure of the sight tube. I machined down some brass pins to make an interference fit with the AN fittings at the top and bottom of the gauges and drilled 0.040" holes in them. Once they are pressed into the fittings they can never escape and cause issues themselves, and they restrict the fuel to a much more manageable flow should the clear tube ever break. They also reduce the sloshing in the gauge as a bonus.

Great idea. I read somewhere that a rivet could be pressed into the fitting, then drilled out which was how I did it. If I did it again, I'd go for the smallest hole possible to help reduce the fuel movement in turbulence which would make them more accurate.

[Bcone1381]

There is more than one data point shared here. One point not yet shared is the plastic Tygon tubing system is FAA approved via STC for a Supercub.

https://fadodge.com/fuel-system-sight-gauge/

[Battson]

Great idea. I read somewhere that a rivet could be pressed into the fitting, then drilled out which was how I did it. If I did it again, I'd go for the smallest hole possible to help reduce the fuel movement in turbulence which would make them more accurate.

Is there any easy way to do this, without needing a tiny drill? Perhaps a slot cut?

[Nev]

Is there any easy way to do this, without needing a tiny drill? Perhaps a slot cut?

Yes I think a slot is probably a very good idea, although I haven't tried it. In my experience, drilling a hole even with a tiny drill, allows too much fuel sloshing.

[TimTall]

I used a 1mm (0.040 ish") drill. I'm not sure it would be possible to cut a slit much smaller than that. But Nev is right, the fuel does still slosh around, but much slower than with no restriction. My last plane had no restriction and the gauges were almost useless in any kind of turbulence.

[marcusofcotton]

Quick search led to Amazon set of bits that would allow some experimentation for not much money. It says they are premium quality so they must be great stuff! Well they might be able to make it through aluminum anyway... McMaster-Carr has individual small bits couple bucks each, I'm sure you'll find sources local in New Zealand as well. Of course many drill chucks won't go small enough to use them so check that.

https://www.amazon.com/Micro-Drill-0...3890402&hv pos=&hvnetw=g&hvrand=16303747628679991748& amp;hvpone=&hvptwo=&hvqmt=&hvdev=c&amp ;hvdvcmdl=&hvlocint=&hvlocphy=9019746& hvtargid=pla-572951892852&psc=1