Learning from an owner annual

Private wrote:
"Jim Macklin" wrote in message
news:EZF9g.20244$ZW3.18025@dukeread04...
I've heard of owners replacing the standard fasteners with
nice shiny stainless steel screws. Trouble is you can get
dissimilar metal galvanic reactions and then you have to
drill them out.


I am aware of galvanic corrosion, which often corrodes aluminum when it is
in contact with steel, especially if in the presence of moisture and even
more especially moisture with salt. The use of stainless fasteners should
AFAIK greatly reduce corrosion of the fasteners but am unaware of any change
to the galvanic corrosion rates on the aluminum. Are you suggesting an
increase in galvanic action between a stainless fastener and a plain steel
nut? Please expand.

What I have heard is this. If you use a carbon steel screw in the
aluminum structure, the corrosion occurs on the steel screw (rusted
screws). To correct the problem, you just replace the screws. If you
use stainless screws, this changes the galvanic status of the
connection to where the aluminum becomes the metal that corrodes. This
means that if you allow corrosion to occur, the aluminum structure
around the screw is what corrodes instead of the screw. To correct this
situation, you have the aluminum structure around the screw to replace,
which is much more involved and expensive than just replacing the
screws.

I would also appreciate comment on the use of thread lubricants like
'Nevr-Seize' which IMHO allow increased clamping force and also greatly
reduce thread seizing from corrosion.

Use of a good corrosion preventative like corrosion X or ACF-50 should
prevent any corrosion of the structure, if you keep it applied every
annual.

I find never-seize on threads to work magic minimizing corrosion, but
one has to be very careful not to get it on the phillips head or the
phillips driver. Even traces of it (or paint) make the drivers cam
out. Buy lots of spare screws and drive bits. Use solvent on the
drivers and the screw heads.

It doesn't help that those damn AN structural screws (can't remember
the number) are so soft and the phillips socket so shallow that the
heads strip out much easier than those unapproved pan head stainless
fasteners. I don't know what they offer except of course a full
diameter shank and a lot of ductility.

Some of you must live in a very corrosive environment though.