Fuel Line Grommet

[szicree]

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.

[sportpilot]

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.

[Mel]

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.

[szicree]

Thanks for the quick replies.

[Steve Sampson]

Steve - if you do pictures, I would be very interested to see your pipe runs on the -4.

Thanks.

[Sparky]

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.

[szicree]

Bulkhead fittings are easier, but each one introduces two possible leak sites.

[szicree]

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.

[Steve Sampson]

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.

[RV8Squaz]

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