I like your idea of doing it yourself, as the time involved can add up
quicker than you realize. Anyone you pay to do it and who does it right
will probably have to charge several hundred dollars to do it. You can
do it I'm sure judging from what you have said. You sound like you have
a good approach planned out. I did a fairly extensive repair on my
Cardinal three years ago and the repair has held up so far. I had to
replace the attachment points around the spinner where the top and
bottom halves screw together. I would recommend you use Kevlar 49
instead of glass as it has better dampening properties than glass, and
tends to last longer and not be as noisy. You can get a yard of it from
Aircraft Spruce for under $20. Glass will be OK if you want to go that
way. I agree that you should use epoxy instead of polyester, as it is
much stronger. Spruce has a special one cheap that is specifically for
Kevlar. I used it and the results seem to be very strong. It is very
liquid and wets out the fabric well. I also agree with the others that
recommend you grind away the delamination and then re-lay fabric in.
Take your time, you'll be glad you did!

Regards,
Bruce Cunningham
N30464 C177A


Bob Chilcoat wrote:
We have a '74 PA-28-180 - the first year this model was called an
"Archer".
The cowl is not in the greatest shape, partly because of its age, and
partly
because one of the partners a few years ago landed on a runway that
was
about 18" too short and slid gently into the chain link fence at the
end
:-( Engine has had all the AD required inspections, etc, but the
cowl did
get a few bruises. We're into our annual as of yesterday and we have
two
problems that need to be dealt with ASAP.

The first is that there is a slot in the back of the bottom cowl were
it
slides over the nosewheel strut. To keep the two halves of this slot
from
flapping around aafter it's installed, a (roughly 12- 15" long)
aluminum
"bridge" is screwed across the gap after the cowl is put in place,
held in
place by four screws and large trim washers that go through the
fiberglass
of the cowl and into the aluminum bridge. Two of these screws, at
the outer
ends of the bridge, are fine. The two nearest the slot, however,
have been
pulled away from the fiberglass, and now have nothing to go through.
The
corners of the fiberglass that they used to go through are simply
gone.
Someone at some point riveted a strip of aluminum to the back edge of
the
fiberglass, and the screws now go through this, but the aluminum
strips are
bent and the cowl no longer fits flush. We really need to remove the
cludgy
aluminum strips and redo the fiberglass so that the cowl fits better.

Of course one problem is that this area is very oily from years of
Lycoming
Leakage (LL). My first question is, what is the best solvent to
remove the
oil so that a repair has a chance of adhering? I plan on cleaning
everything and then thinning the glass a bit roughly 1.5 inches back
from
the edge, and then feathering and building up the area with glass
cloth and
epoxy to remake the back edge of the cowl (I've done a lot of boat
building
and repair, so this isn't rocket science to me, although I've always
worked
with polyester resins before). Next questions are, what is the best
fiberglass for this? mat or cloth? S-glass, E-glass or something
else?
What epoxy is the best for repairs? Is there a kit available
somewhere with
everything (glass and epoxy) I need? If I want these quickly, what
source
should I use? I've seen complaints about Aircraft Spruce. Would
Wicks be
better for fast turnaround? Someone else?

The other problem with the cowl is that there has been some
delamination
near the top of the low cowl where the propeller shaft opening is
formed.
This area has a lot of curvature, and there is a foam or balsa wood
reinforcement bow epoxied into this area behind the curved opening.
The
cowl molding has pulled away slightly from this reinforcement bow.
Not very
much, but the A&P thinks that this should be closed up before the
delamination propogates further. This is a more difficult problem,
because
there is very little clearance to get anything into the gap, there
doesn't
seem to be an edge to overlay a patch onto, and of course I have no
idea how
much oil has drifted in there that would prevent adhesion.

My current plan here is to wash it out with some solvent to get most
of any
oil film out of there, and then inject a thin epoxy as deeply as
possible
into the crack with a syringe. Questions here are mostly about what
solvent
won't dissolve the reinforcing bow if it's a foam and not balsa wood,
and
where can I get a really thin, watery epoxy. Also, does anyone have
any
other ideas about fixing this area?

Of course, we'd like to get this all done before the annual is done,
so that
the plane doesn't have to sit outside without a cowl. The last
question is,
is there someplace someone can recommend that we could have this
done? I
really don't have the time to do this, but will make the time in
order to
get it done right if necessary. I've thought of calling bodyshops
that
specialize in Corvettes, and boatyards, but they don't usually deal
with
weight issues. I can just see a quarter inch of heavy polyester and
glass
roving added to the inside of the cowl. I'd rather not have to log a
major
CG change.

Anyway, any and all suggestions and advice would be greatly
appreciated. I
woke up early this morning thinking about this. Maybe I can go back
to
sleep now. Thanks, guys.

--
Bob (Chief Pilot, White Knuckle Airways)