Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml@lancaironline.net
Date: Sun, 06 Jun 2004 07:12:34 -0400
Message-ID: <redirect-141399@logan.com>
From: bob mackey <nospam@pure-flight.com>
Subject: Re: [LML] Wing Wire conduct
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>> The black electrical conduct that Lancair supplies needs to be completely
>> sealed in the fuel bays. Has anyone used an alternate material that only
>> needs to be sealed at the ribs?

> Why not use thin-walled aluminum tubing? It's lighter than the plastic hose,
> fuel proof, and meets your "sealed-at-the-ribs" criterion. Just a thought.

Here's one reason not to use aluminum tubing as conduit in a lancair fuel bay:

The thermal expansion coefficient of aluminum is very different
from the glass and carbon used in the rest of the wing. At temperatures
much different from the construction temperature, the aluminum tube
might pull (cold) or push (hot) on the ribs enough to create new fuel leaks.

Figure the length of the run and the differences between the hottest and
coldest service temperature to determine the total strain. See if your ribs
will comfortably accept that amount of strain.

The same forces will also cause the tubing to expand and shrink relative
to the hole they pass through. Make sure the bond is flexible enough
to accomodate that strain as well as the longitudinal strain.

- bob mackey
  flying a 235
  building a 320
  103MD -at- pure-flight.com
  [use this email address - the one at the top is spam bait]