Cowling Crack Repair

[bxg007]

How would I go about getting cracks repaired in my cowling?  I at lease want to minimize the chance of this spreading.  Attached is a photo.  Can this type of repair be done locally or will I need to have the whole cowling shipped out?

 

Thanks,

 

-Bill G

 

KHFY '91 M20M

 

 

 

[1964-M20E]

The way I see it you have several choices

1. If you are good at fiberglass work and if you are comfortable with doing it you can do it yourself and repaint to match.
2. If not a local body shop with fiberglass experience could help you.
3. Local fiberglass boat builder
4. Local A&P with fiberglass experience
5. Find someone else to send it out to??

[FBCK]

I guess this is quite common, I mave it on my cowling as well.  I had been repaired before, not correctly and within two flights had returned.  I think the MSCs actual have a repiar kit that with strengthen the cowling.  I will do something to mine when I get the plane repainted.

[RJBrown]

Mine got hail damage last summer. Rocky Mountain Straight flight fixed everything and reprinted it.

[N201MKTurbo]

I have done way to much cowling repair. Just make sure you use the right materials! The Mooney cowl is done with epoxy. A lot of people will try to repair it with polyester resin. This is a big mistake! Polyester will not bond to epoxy, it is stiffer then epoxy and will delaminate very soon.

If you don't have ready access to a good selection of epoxy just use West Marine 5 to 1. it is excellent, but a bit expensive. Order the cloth from Aircraft Spruce get 3 OZ e glass.

You will need a right angle air sander with the screw on pads. Get some 80 grit and some 200 grit. You will need an electric finish sander and a good collection of sanding blocks.

If you don't have body working skills take it to someone who does.

Grind the paint off for about two inches around the crack. Grind the fiberglass down till there is no crack don't worry about going through, that is Ok. taper the edges down for at least 1/2 inch around the crack.

Buy a box of 1 inch paint brushes from Harbor Freight, you will be throwing them away after using them. Get a bunch of Dixie cups for mixing the epoxy. Get some graduated cups from a paint store. Get a box of rubber gloves. Don't mix more then 1/4 cup of epoxy at a time or it will catch fire. Put a drop cloth under your work area or you will be sanding epoxy off your floor. Cut your cloth into strips bigger than the ground out area. Have a bunch of the strips ready before you mix the epoxy. Be precise about mixing the epoxy. Mix the epoxy in one cup and then pour it into another cup and mix it again. Paint the whole area that was ground with epoxy, lay a strip of cloth over and paint that strip with epoxy. Lay another strip of cloth and paint with epoxy. Keep doing this until you run out of epoxy or you are higher than the top surface of the cowl. Let the epoxy harden, this will take anywhere from 5 minutes to two hours depending on the epoxy you used. Use the air sander to get it to about the top surface of the cowl, then use sanding blocks to work in the contour. If it is below the surface, repeat the following steps and build it up some more. For the final finish coat mix some Cab-O-Sil (fumed silica) into the epoxy and spread it on like bondo and sand. Use a sandable primer for the final surface finish.

Take an inspection plate with the proper paint color to the local auto paint store and have them match the color. get a good two part urethane like Imron or Nason and paint it to the first stripe.

 

Or just leave the crack alone, it will be OK for another 20 years.

[DaV8or]

Keep doing this until you run out of epoxy or you are higher than the top surface of the cowl.

 

And if you don't wear a respirator, you'll definitely be higher than the cowl!

[N201MKTurbo]

Yes, I forgot that part...

[bd32322]

Also skin protection ... Some people develop allergies to the epoxy

[Bob]

_{Semi trucks have many fiberglass parts and are painted using Imron.}

_{So if you use a body shop for the repair, one that specializes in Semi trucks would be a one stop shop with proper knowledge to do it properly.}