Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Fri, 14 Feb 2003 10:27:20 -0500
Message-ID: <redirect-2023723@logan.com>
From: "Ted Stanley" <ted@vineyard.net>
Subject: re: tube protection
MIME-Version: 1.0
Content-Type: text/plain;
	charset="iso-8859-1"
Content-Transfer-Encoding: 7bit

>From Gary Casey ....... "Aren't all the tubes anodized when we get them?
That would imply that unless you scratch through the anodize layer you
shouldn't need to do anything with them."

Anodizing only affects the exterior surface of the tube. It cannot treat
more than a few inches of the interior of each end of a long tube. Typically
it's not the exterior of the tube that's the problem. It's the entrapment of
moisture and electrolytic action from electrically dissimilar materials
(carbon and aluminum for example) that causes the corrosion to start on the
INSIDE of the tube. The problem is that interior corrosion is difficult to
detect unless it penetrates the exterior of the tube and by then you have a
potentially dangerous situation.

Probably the best solution is to treat the interior of control tubes and
plan on a visual inspection of at least one representative tube on a
periodic basis. If all the tubes are treated the same and have at least
similar connections with dissimilar materials then subsequently finding one
corroded tube should be cause to inspect the others.

Personally I'd like to hear from owners of high time older Lancairs who have
actually inspected the interiors of some of their tubes. I imagine some will
have a problem and some not. I would expect that those aircraft in areas
near warm salt air to be most affected.

Aluminum brake lines can be affected, but as a practical matter failure
usually takes the form of a pin hole leak which becomes quite apparent but
rarely results in total failure of a system.

Ted Stanley