From: "Scott Dahlgren" <dahlgren@itsnet.com>
To: "___Lancair list" <lancair.list@olsusa.com>
Subject: gear leg coatings
Date: Fri, 11 Jun 1999 07:52:38 -0600
Message-ID: <NBBBIPBKBOKGEELJMONFKENICHAA.dahlgren@itsnet.com>
Importance: Normal
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John,

I talked my our coatings guru and he offered up a few ideas on what to do
with your gear legs. He has tried them all for wear and corrosion and
thought the best option was to Nickel plate them. it is about the same price
as chrome, protects much better and has no stress problems. there are heaps
of plating houses in the Thomas register on the web that do electro and
electro-less nickel. if you have all external surfaces to coat, the electro
type is better. He also said that there were other coatings that would work
such as titanium nitriding, but you have to take your parts up to 900° C (no
aluminum parts here) and nickel's qualities are well known.

he said that there are two methods he knows of for "low stress" chrome
coatings:

use regular crystalline form chrome 2-15 mil thick but bead blast the
surface prior to application very thoroughly. this puts the surface in
compression and keeps the tension risers at the chrome interface from
attacking the part. if the part is flexed enough to yield the surface
though, you're in trouble.

use high density amorphous (non-crystalline) chrome. it can be layed on very
thin, lowering stress levels and is softer.

he feels chrome is very good as a machine wear surface as it is very
crystalline and hard. As a corrosion inhibitor, since it micro-cracks during
application you get microscopic corrosion at the crack lines which
eventually make it flake and further add stress. On the web I found lots of
AD's on chromed parts on a FAA+chrome search (try google.com-it is the best
search engine out there for technical searches)

I found an FAA chrome shop in California that can be reached at
http://www.uschromeofca.com/ or 562-437-2825 they may be able to answer more
of your questions.

Scott

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