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Repairing cracks in (oily) fiberglass

R

rvbob

Member
I'm looking for advice on how to repair the small cracks that have appeared on my RV-3's cowling over the years. Naturally, they are certain to have trapped oil/grease/dirt. Any successful (or otherwise) experiences you can share?

Bob Knauff

RV-3
 
How bout a bit more info.

Epoxy or polyester resin??

Gel coat or not?

Solid layup, or honeycomb core?

Surface crack on the exterior, or interior, or full depth crack??
 
I think that the general techniques for simple composite repairs are shown in AC43.13. Another good reference is Ursula Hanle's Plastic Plane Patch Primer.

You grind out material at some reasonable scarf angle (I'd use something like 20:1 for a non-structural thing like a cowl). Degrease it (I use acetone), and then lay up your repair patches, largest to smallest. For a cowl, I'd cut all the patches so the fibers are +/- 45 degrees to the crack.

Thanks, Bob K.
 
az_gila said:
Are you sure on the epoxy bit?

I thought the original early -3, -4 and -6 RV glass parts were all polyester....
Click to expand...

Bad assumption on my part, perhaps. It is a kit cowling that was purchased sometime in the 1980s. Therefore, it was whatever it was.

Can anyone tell me how to detect the difference, just to be sure?

Bob Knauff

RV-3 N65ZM
 
I think you should check with Vans, they should know the material used in your cowling.

My $$ is on polyester.......

As to the repair, Bob has it already well said.

Clean, and roughed up are vital factors.

Good luck.
 
Whatever it is made of, if you are using epoxy for the repair, you shouldn't have a problem.
 
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