H in t s F or H o m e b uil d e r s
Use a Sharpie Marker on Aluminum Planes
Don't use a pencil!
By Gary Baker
If you have worked on an aluminum airplane, you have
probably heard that you should not use a pencil to mark
the aluminum parts. That's because the carbon graphite
will get into the crevices inherent in the aluminum surface. The combination of carbon and aluminum in contact
with one another will set up galvanic corrosion that will
not become evident for some time, but it will become
evident. The corrosion can only be stopped by removing a
few thousandths of aluminum.
Van's Aircraft and other kit manufacturers recommend that
a Sharpie be used on aluminum parts instead of a pencil.
The Sharpie can be removed with lacquer thinner or enamel
cleaner prior to priming or painting, and it will not damage
the material. Lines on aluminum marked by a Sharpie can
also be left on the material before priming, if they are needed
for reference and the material will not be painted later. If
the material
will be painted,
the Sharpie
lines need to be
removed first.
The lines will
show through the
primer and paint!
Here is an illustration of Sharpie bleed-through. The lines
were drawn on the forward side of the vertical stabilizer
spar of my RV-6 after priming. This area of the spar lies
against the fuselage bulkhead and will not be seen, so I
did not bother to clean off the lines. The lines are bleeding
through five coats of primer and white paint. So, make sure
to clean off those Sharpie pen marks, if you don't want them
to be seen!
Watch These Online Hints for Homebuilders Videos!
Here's four new videos that were released recently.
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timing. Dick is a Technical Counselor for EAA Chapter 186, A&P; aircraft mechanic with
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Diagnose low cylinder Compression
After performing a differential compression test you may have low compression on one or
more cylinders. Dick and Bob Koehler demonstrate ways to determine what may be the
cause of the low compression reading.
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In this video, Dick Koehler demonstrates how to install a cotter pin in the engine mount
castle nut.
EAA Experimenter
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