REFLECTOR: fuel line

[dohayes at aol.com]

My mid 1990's vintage instructions said the same thing, with clamps holding
the hose on the tubing. When I put it all together many years ago, before
Crossflow handed me a ten year delay, it seemed fine and passed leak tests.
However, when I recently added fuel, I came back a few days later to find
the contents of my tanks sitting in the bottom of the fuselage. The plastic
tubing supplied with my kit slowly softened and swelled upon exposure to
fuel, to the point where the supplied clamps were unable to keep even
pressure on the hose. I have since added hose barb connectors with the same
hoses and clamps, with no leaks.

If I were to do it again, I would probably still use hose, but I'd embed a
block of aluminum in the strakes and thread them for hose barb connectors
instead of using any aluminum tubing at all. This is the method used
elsewhere, such as the sight gauges and the sump, maybe even without the
block of threaded aluminum in some cases, and it works well.

Other evidence of the swelling of the hose was seen later, when I added
enough fuel to fill the sight gauges, and they bowed significantly. It
wasn't a big deal to cut out an inch of tubing and put it back, but one
could soak the tubing in fuel before installing them and save some trouble.

By the way, I'm not using aviation fuel, so results may vary, though its
hard to say what the unleaded replacements for aviation fuel will do when
they become available.

Doug Hayes
Boulder, CO
Velocity 173FG
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