Mounting the sight gauge

[svyolo]

I am making up the sight gauges and trying to figure out how to mount them. I was going to cover the inside of the fuselage-wing attach section (removable) and I am going to put the sight gauge just outside of that, inside the cabin. I am using Battson's PVC type sight gauge.

I was thinking about just using double adel clamps (maybe with an angle in between) to clamp down on to the flare nut. I wish they made a 90 degree bulkhead fitting with pipe threads on one end but I can't find one.

[Ed Welfred]

I could not find bulkhead fittings for the fuel sight gauge so I ordered part # 04-02163 from Spruce. I removed the prong then ran a 3/8th fine die up the fat end. Fuel gage bulkhead elbow.JPG

[rodsmith]

I welded .040 tabs to the inside of the wing root tubing, and used AN822 elbow fittings. Using the correct combination of washers under the flare nut can make a tight connection without a bulkhead fitting.

[James]

Yes, I wasn't sure how to do that either, but here is what I'm running with:
1) I have aux tanks, so the outlet from the pump is plumbed into a T-bulkhead fitting mounted inboard of the root rib, uphill end of the sight gauge.
2) This tee doesn't have an NTP thread to the root, it's flared (I don't think you can get flared/NTP T fittings).
3) I made up a short piece of 5052 tube, as short as possible allowing for two B-nuts and room to insert the die of my flaring tool. It was about 2" long.
4) After flaring, I put a piece of 1/8th control cable up inside, and then dragged the tube around the big end of a 1/2" breaker bar, to form a 90 degree angle (requires some muscle).
5) There was a small amount of flattening, but I could drag the piece of cable out, so there is still enough tube crossection for fuel to flow/equalise in the glass.
6) At the bottom end of the glass, I ran a flared tube out from the tank through both bulkheads, which terminates in a 90 degree flare / NTP fitting, AN822 from memory.

This arrangement gives the advantage of anchoring the tube to something pretty solid at the T-fitting. The glass ends up about 1-1/2 inches away from the inboard rib. I haven't made my fuselage yet, so I have no idea if this will work when the wings are hung, but it's easy to adjust later on if needed.

Hope this helps,
James