Gentlemen,

I have a question regarding a small repair I need to make. Im repairing the firewall that is attached to a fiberglass fuselage. It is slightly cracked where the two meet and the firewall needs to be epoxied again to the fiberglass. It is not completely apart from the fuse so can really just push back in and reapply epoxy on that area. Should I take the firewall completely apart and sand the fuse so that it makes better contact or is this overkill. Also I am using tri-stock to reinforce the firewall to the fiberglass but is there anything I need to know about gluing the two together? Minimal damage was done to the front fuselage and I was thinking about using white medical tape (epoxied on both sides) to simulate the fiberglass front section of the fuselage. Once it hardens I plan on sanding it down and then painting over. The cowl will cover most of the damaged area. Does anybody have something to add to this or is this good?

Did it just come unglued from the fiberglass, or is something actually broken? If it's just unglued, your plan of regluing and then reinforcing it should work fine. If it's broken, you may need to build up a fillet on the inside to keep it from breaking again.

No, firewall is completely intact. Fiberglass surrounding it is a bit cracked but not bad at all.

Well, a little light fiberglass cloth and epoxy go a long way to help fix problems like that as well as reinforcing the area that may be cracked. You can probably do it from the inside so nothing is aparent from the outside, and if you take care, you won't add weight to the nose.

CGr.

Pictures would be a great help here but I would wick some thin CA into the break then abrade the firewall/fuse joint really well on both sides and add a fillet of epoxy and milled fiber then cover with a layer of 6 oz cloth.

I can never keep this straight, sorry. There are two types of epoxy/resins used to make up a glass fuse, they don't stick to each other very well. There is often a releasing agent film left behind from the mold too so your fuse must be cleaned real well or even if you have the correct resin it doesn't stick well.
Because I have never been able to keep the two straight in my head I started using gorilla glue for a lot of my glass repair. Reinforcing behind the fire wall is a very good idea. Do some testing on your fuse to make sure what you use will stick correctly.

Hi Gene et al,

Hope you all had a great Christmas and an even better New Year awaits us all.

Epoxy sticks to polyester and itself. Polyester only sticks to polyester. All surfaces need to be abraded/"roughed up" and then cleaned with acetone to remove any mold release agent and ensure a good bond prior to repair.

Cheers,

Colin

See what I mean, I can never remember that!!! At least I remembered epoxy doesn't always stick!! Sticks really well to my fingers though!
I was just out in the shop removing last years girls for this years. New babes always equals a good Xmas!!!
Gene

Epoxy doesn't stick to polyester very well. Only good joint is to fibreglass and polyester the firewall to the glass fuselage.