Sight Tube.

[NWade]

Although it's another item to wear out and another set of fittings to possibly leak... ;-P Everything is a trade-off!

[vwglenn]

Although it's another item to wear out and another set of fittings to possibly leak... ;-P Everything is a trade-off!

Also true. It's a vicious circle.

[mike.smith]

I had sight tube routed along edge of panel and down side of fuselage. gave readings for bottom of tank. BUT I removed it after two years when found tubing had gotten so hard it was brittle. It actually snapped in half when removing it. My Princeton prob has worked well connected to the GRT Sport SX, but I use only Avgas, and the red cube flow sensor into same Sport SX has also been reliable so no longer saw need for sight tube that looked to present its own hazards.

Are you sure it was fuel line? I made the mistake the first time, of using something I thought was clear fuel line. Luckily I put a piece of it in a glass jar of 100LL at the same time. A month later it had turned slightly yellow, and had become hard and brittle. It was NOT fuel line! So I took it off the airplane (I was still building at the time), and bought "real" clear fuel line. I have had a test piece submerged in fuel in that glass jar now for about 18 months. I take it out every now and then to check it. It's perfectly clear, and just as flexible as the day I bought it. If it's the real thing, it should last quite a long time.

[DCASonex]

Mine was in place with for three years, two with fuel, before I found it had hardened in spots, Was stiff full length, but very brittle only in some spots. Was worst where I had line covered with ACS's blue fire-sleeve, but that included where it came off bottom of tank and was most vulnerable to damage. I use avgas only and where it had gotten most brittle, it had also turned or was stained a shade of blue. Might have been wrong material, or might have replaced it with same, and been good for another couple of years, but just did not see the need to have that additional potential failure point in there.

David A.

[gammaxy]

I really considered what Sonex did here:

A nice slot in the panel to see the tank through. Perhaps a light on the rear of the panel with a momentary contact switch to see the level with ...

Dale
N319WF

I really like the elegance of the slot with light idea. On a recent long cross-country flight I used my camera to take pictures of the tank to cross-check my gauge. It seemed to work pretty well. My main caution is that individual pictures might not capture if the fuel is sloshing.

[vwglenn]

After sitting in the plane and pondering fuel for some time (also cleaning up wiring).

1. Just bending over to look at the tank is out.
2. Installing a mirror on the copilot side under the panel might work but the mirror I was using at the time is broken and I can't see enough of the tank with it to tell if it would work. Then there's the problem of checking the fuel with a passenger aboard and writing numbers backwards so they're clear in a mirror.
3. I could make a little door on top of my panel to pop open so I can peek at the tank while in flight. That might require an LED installed somewhere so I can see.
4. Possible peep hole in the front of the panel too. but I think my EFIS it too deep to get a clear shot of the tank that way.

[Rynoth]

What about carrying a small hand-held mirror in the airplane? Maybe in combination with a small light, either a flashlight or a light mounted on the back of the panel?

[daleandee]

*

[Rynoth]

Neat idea Dale!

Or, if using a cell phone, rather than take photos of the tank, take a video of the tank for a few seconds, then watch it.

[Bryan Cotton]

Or if you mount your ipad on the panel, drill a hole under the camera.