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szicree

Well Known Member
Plumbing a slow build 4 is pretty much an on-your-own kinda deal and so I have a real simple question for you that have already plumbed your planes. What size grommet did you use to pass the fuel line through the side skin of the fuse? I just did one with a grommet that requires a 5/8" hole, but it occurs to me that this only provides 1/8" of rubber between fule line and skin edge. Chaffing seems unlikely since everything is rigid, but obviously this is not an area where you want metal on metal. The next size up that Spruce has would require a 1" hole, which seems kind of big. I know it's a minor detail, but I'd love to hear what others have done. Thanks people.
 
gromets

We just did this in an RV9a and the fuel line required a one inch hole and a soft rubber gromet. It wokrs good. the vent line required a 3/4 hole and the same type gromet. I used the unibit to drill them out.
 
I recommend going with the larger grommet. 1/8" is not much "padding". Even though the line is rigid, it can still be bent quite easily.
 
Why not an AN bulkhead fitting?

Is there a reason large holes with grommets are used here instead of AN bulkhead fittings? It seem to me that bulkhead fittings would be easier to work with.
 
Steve,

Here's some pics of my fuel plumbing thus far. Nothing fancy. The left side is going to be similar to the right except it will bend toward the leading edge to connect to my flop tube.

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Flop tube

Steve - thanks for that. Very interesting and helpful. I really find pictures of other people's details helpful, particularly with the -4 where so much is undefined.

One question. On the left, to the flop tube, how do you plan to get past the tank support bracket? Over, under or through. I had wondered if I should take the pipe forward inside the cockpit and then out opposite the tsnk exit. It might get in the way though.

Thanks again.
 
On the RV-8, the fuel line for the flop tube goes through a 7/8" or 1" hole in the spanwise flange of the fuel tank attach bracket. I'm not sure if the RV-4 would be any different but you could ask Van's about it.

Jerry
 
Steve Sampson said:
One question. On the left, to the flop tube, how do you plan to get past the tank support bracket?
Click to expand...

That part was definitely a puzzle. To get around the tank braket required bends that were way too tight. What I came up with is two 90 degree fittings, one out of the tank pointing aft and up, and another connected to it to take the line aft and down. This combination does a good job of getting up and over the tank attach. I'll try to post a pic when I get a chance.
 
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