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Install two aluminum brackets from the firewall
down to the rear of the lower cowl and fasten to the lower cowl with flat
head or tapered screws.
Also install additional graphite or glass
bid near the seam joint between the air intake holes and the prop shaft
hole. I have done so and do not have spider cracks often seen on other
cowlings. Run the glass about three inches above and below the cowling
seam line.
If you use piano hinge and rivit same to the upper
and lower cowling; use one bid of standard weight glass bid over the rivets to
eliminate their eventual paint cracking around the rivet. I used very
lightweight glass used for model airplanes and it was too light.
I had some hanger rash on the cowling. To fix
it I stoppped drilled the cracks,placed two bid under, two bid over and tapered
and body work. After three years those spider cracks reappeared. I have heard
you need to grind those cracks out and fill with flox or other method prior to
patching as stated above. Perhaps someone with more direct knowlege about
this subject can enlighten us.
Gel coat is a pain. If I had my rathers I
would like to work with straight glass.
Reinforce the top cowl to give it more
rigidity. The top side does flex and eventually might sag with
constant heating and cooling. place a foam strip maybe 1/2 or 5/8 thick by
about 1 1/2 inch wide with rounded corners from front to rear and cover it
with a two bid glass bonded one inch on each side of the foam. This
beam should be strong enough to support the top cowl and suppress
drumming. I covered the inside with two ply graphite. It was heavy
and may be more than necessary.
Bob Smiley
N94RJ
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