Subject: RV4 fuel plumbing details.
From: rotaryeng
Date: 10/18/2013, 7:29 AM
To: AAA-rotaryeng

I don't know whether it was Mike the builder or Van the designer that came up
with the flawed  plan to get the fuel out of the wing and into a fuel pump.
As I recall this was a difficult area to work with on Dave Leonard's RV6 when I helped
to take the wings off after he landed on a high way.

There is about 3 inches between the root wing rib that has a AN-6 male fitting
and the side of the fuselage structural sheet metal. This gap is covered with
an aluminum  fairing strip screwed on with a bunch of flat head machine screws to
streamline the joint between wing and fuse.

The fuselage panel already has
three  holes about an inch diameter which is three too many. Unfortunately the
fitting location on the wing rib is adjacent to a structural aluminum angle riveting
to the structural sheet metal fuselage side so another large hole is out.

So I needed a S shaped hose to go from the wing root AN fitting to an existing
hole in the fuselage  side near the fuel pump. One can do it with a longer 180 degree bend
of SS braided hose and 2 right angle hose ends but I just did not like that Micky Mouse solution.

I tried two right AN-6  angle hose ends and a very short piece
of SS braided line.  Still too long. I tried a S shaped aluminum tube but the distance
between the coupling and the fuse side was too much so I could not get the coupling
on the wing root fitting. I even tried modifying the flaring tool with a 1/2 inch drill
to get the coupling closer to the bend. There is a limit to the smallest radius one
can bend 3/8 OD aluminum tubing with out crinkles.

Plan E or F: Braze a piece of 3/8 OD aluminum tube to a modified right angle AN-6 hose end.
You got to get those rubber O-rings out of there :) If you have never taken one of these expensive
jewels  apart this is what they look like inside. I have SS wired brushed the blue anodize
off already. Can't braze to anodize.

That is what I plan to try next unless all you people can come up with a better idea.

Paul Lamar

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