Message-ID: <005b01c041fa$58f2a3e0$950b4a0c@t3g3m5>
From: "Jeremy F Fisher" <exhibs@mindspring.com>
To: "Lancair List" <lancair.list@olsusa.com>
Subject: 320/360 Fuel Leak Testing
Date: Sun, 29 Oct 2000 17:48:24 -0500
Reply-To: lancair.list@olsusa.com
Mime-Version: 1.0

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I reported earler on my problem with a fuel leak from around the aileron
bellcrank mounting bolts.  I ended up cutting a 5 inch hole in the lower
surface of the wing going in to seal the leak, and then repaired the hole.
The worst part was steeling myself to cut the hole in my just-finished wing!
I found that the problem was self induced.  When I pressurized the wing, I
had popped the joint where the wing rib joins the lower wing surface, so
that there was a gap along about 3 inches.  I remember hearing a slight
cracking noise, but thought no more about it.  Just as well that I cut it
open as no amount of pulling sealer through a vacuum would have coped with
that.  I sealed it with a Hysol/flox mix and covered it with fuel sealer.  I
then sealed the hole by glueing a 3 bid plate to inside the wing, replacing
the 5 inch plug with Hysol/flox, and covering the whole thing with 2 bid.  I
made the plate by moulding it on the outer surface of the wing before
cutting the hole.

Thinking about it, I realize that I had suffered from idiot syndrome when I
tested the wing.  I forgot that when the water rises in the manometer up
tube, it also falls in the down tube, so I had applied nearly 2 psi, instead
of 1 psi.  Duh!

I am confident that this repair is solid and safe.  Now I have to check for
other leaks, and I am looking for advice as to the best way.  I am a little
leary of the pressure test (once bitten), and from previous posts in the
List, I believe that you can still get gas leaks even if the wing is air
tight.  The alternative seems to be to fill it with gas, which is messy and
can be dangerous.  Does anyone have a better way?  I would hate to paint the
wings, and then find I have a leak.

It was interesting looking at the glue line from the inside.  I had thought
that I had overdone it with the amount of Hysol used when I sealed the
wings, but there was just a small seam of Hysol visible inside.  The lesson
is that you really need to use a lot of Hysol, and don't worry about it
squeezing out inside.

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LML website:   http://www.olsusa.com/Users/Mkaye/maillist.html
LML Builders' Bookstore:   http://www.buildersbooks.com/lancair

Please send your photos and drawings to marvkaye@olsusa.com.
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