Date: Mon, 21 Feb 2000 08:46:16 -0800
From: fmoreno4@postoffice.pacbell.net
Subject: Electrical Conduit in Wing - LIV
To: lancair.list@olsusa.com
Reply-to: fmoreno4@pacbell.net
Message-id: <38B16BD7.1993D34E@postoffice.pacbell.net>
Mime-Version: 1.0

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Be advised that many fuel leaks in the LIV occur at the leading edge
because the tight radius combined with the porosity of the prepreg and
difficulty in applying fuel sealant in that tight space leads to
localized porosity and leaks in that region.  It also turns out that
these leaks are hard to find because the surface, being vertical, sheds
soapy water.  Finding leaks requires applying soapy water and then Saran
wrap and watching for bubbles under the Saran wrap. The leading edge
also takes hits from rocks, possible hail, and hangar rash and these can
lead to fuel leaks.

Given all this I think Lancair made a great decision to add the carbon
web in the leading edge and use the space for electrical wiring.

Also consider the difference in expansion coefficient between aluminum
and the carbon wing as they are cycled from plus 120F to minus 40F.
(Yes, the fuel gets that cold.  I have seen ice form on wing skins when
parked after descending from high altitude, long flights.)  I think a
straight run of rigid aluminum tubing the full length of the wing would
be asking for cracks where the aluminum is sealed to the bulkhead or
wing rib as it grows and shrinks relative to the wing.  The benefit of
the plastic conduit is that it is moved easily being soft.  Food for
thought.

Fred

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