Archer Cowl needs work - Advice?

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)

Bob, simply injecting resin into a delamination void has zero chance of
holding up... Ditto for riveting aluminum strips to the lower cowl...
You need to use a good grease cutter on the oil soaked areas (simple
green, 409, etc.), followed by several scrubbings with liquid dish
detergent and water, followed by spraying MEK on until it runs off
(don't use bare hands for this stuff as it absorbs instantly through
the skin and goes straight to the liver)
Then you need to grind away the surface of any delamination (from
either the inside or the outside depending on which side is the thinner
part of the delamination) until you have removed the bad stuff and have
a good layer left... The edges of the ground out pocket need to be
tapered/scarfed to at least an 8:1 slope... Then you need to build up
the removed material with unidirectional fiberglass and epoxy resin...
Check the archives at rec.aviation.homebuilding for pointers on this
(the Cozy MK-4 group is a good source of information)... Also, boat
builder chat groups and personal web pages will have pictures of the
proper way to layer the glass in, etc.. Lacking that, ask around for
the local EAA chapter and someone there will speak fiberglass
fluently...
Also, the bottom lip needs to be ground back to solid material... The
edge needs to be scarfed at an 8:1 slope... Then using .032 aluminum
make a form to clamp to the cowl for shaping the new lip... Put a piece
of saran wrap on the aluminum as a release layer... Then lay up new
glass layers...
Your surmise about non airplane fiberglass mechanics is likely correct,
they may just slobber it on nice and thick... If you can find one that
is building his own plane, that would be perfect... Other than that,
shop around for a homebuilder, bound to be one near you... Or give me a
jingle on the phone... None of this is hard once you have seen it
done...

Cheeers ... Denny

On Wed, 16 Feb 2005 05:52:03 -0500, "Bob Chilcoat"
wrote:

We have a '74 PA-28-180 - the first year this model was called an "Archer".

I have done a refurbish to all of the fibreglass on a PA28-140 which
is almost blemish free after 5 years.

The nosebowl on the cherokee is polyester resin so that was used in
the repair. I prefer to work with epoxy but find out what was used
originally on the cowl and use that or something compatible.

degrease the bowl thoroughly with something that wont destroy the
resin used. I used a cheap sprayon engine degreaser then hosed it off
with water. detergent was used after that then I think Acetone just as
a final cleaner. this didnt get all the grime out though it was dry
and oil free so I sanded the surface with a disk sander until I was
back to a layer of good glass. on the outer side of the bowl all the
bog was sanded off with the rotary sander back to fibreglass.
over the years the drumming from vibration had left the integrity
destroyed and the glass was a little spongey to the feel.

repair strategy was to use the existing glass work as the inner ply
then layup 2 or 3 glass layers on each side, making a sort of 3 ply.
it worked well and hasnt looked like deteriorating.
the resin quantity is the old "not white not wet" guidance to good
layups. I used a 1 inch wide chisel of wood to dapple the resin into
the weave and a square piece of plastic ice cream bucket as the
squeegee. keep the layups as light on the resin as possible consistent
with good layup.

to get a smooth outer layer I used a paste of resin and johnsons baby
powder (talc) and squeegee'd this on to fill the weave but not much
more than that. this was sanded back smooth and then it was painted.

bob chilcott's comments on splaying are valid when repairing a missing
section.

remember that you can sand back a layup and add some more and it will
be as good as a single complete layup. you can sand off something that
didnt look too good and try again.

when teasing around small corners having the weave at 45 degrees will
aid the process considerably.

If you have never done a layup then you should watch a video (Mike
arnold's tapes of the AR5 are good) or watch someone actually do a
layup. once seen it all becomes easy.

a critical thing is to get the resin mix proportions exact and dont
contaminate the mix with oils or water. get those right and it will
set off perfectly. dont use glass cloth that has been wet. wetting
glass cloth is a reason for condemning the piece and rubbish binning
it.

like anything aviation it isnt hard but needs to be done competently.
Stealth Pilot

In rec.aviation.owning Bob Chilcoat wrote:
: We have a '74 PA-28-180 - the first year this model was called an "Archer".

: 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

I'm assuming that you're referring to the top cowling, and the curvature
between the cooling air inlets and the prop clearance hole. The shape that is
embedded into the back of the cowling is screwed in from the front! There are
three screw holes covered up on the front of the cowling: One in the center
top of the prop clearance cutout and one on each side, on the up and
down part of the cooling air inlets. This reinforcing shape was delaminating
on my airplane (1968 PA-28-180) and what I did was to chop up some glass
cloth into short pieces, soak them in resin, and pack the recess caused
by delamination. This was 4+ years ago, and the repair is still in fine
shape. Presumably some day it will need another repair, and I will probably
remove the reinforcing shape completely and re-attach it.
--
Aaron C.

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)

"Bob Chilcoat" wrote in message ...
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
snip
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)




Some good stuff he

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/99c827db9baac81b86256b4500596c4e/$FILE/Chapter%2003.pdf

Big file but worth it...

"Blueskies" wrote in message . com...

"Bob Chilcoat" wrote in message ...
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
snip
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)




Some good stuff he

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/99c827db9baac81b86256b4500596c4e/$FILE/Chapter%2003.pdf

Big file but worth it...




Here it is shorter:
http://makeashorterlink.com/?C33713E7A

Stealth Pilot wrote in
:

to get a smooth outer layer I used a paste of resin and johnsons baby
powder (talc) and squeegee'd this on to fill the weave but not much
more than that.

Run that one by me one more time? I haven't heard of this trick.

On Wed, 16 Feb 2005 13:19:39 -0600, "James M. Knox"
wrote:

Stealth Pilot wrote in
:

to get a smooth outer layer I used a paste of resin and johnsons baby
powder (talc) and squeegee'd this on to fill the weave but not much
more than that.

Run that one by me one more time? I haven't heard of this trick.

Most people use something like microballoons mixed with the resin to
create a sandable finish.

Corky Scott

On Thu, 17 Feb 2005 08:16:21 -0500, Corky Scott
wrote:

On Wed, 16 Feb 2005 13:19:39 -0600, "James M. Knox"
wrote:

Stealth Pilot wrote in
m:

to get a smooth outer layer I used a paste of resin and johnsons baby
powder (talc) and squeegee'd this on to fill the weave but not much
more than that.

Run that one by me one more time? I haven't heard of this trick.

Most people use something like microballoons mixed with the resin to
create a sandable finish.

Corky Scott

thats it.

I just checked the ingredients to the baby powder.
talc, fragrance.

sometimes I just do it for the fragrance :-)
smells great while sanding it back.
Stealth Pilot