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