Firewall and cowl repair help needed

[rcflyer]

Hi guys, I had a mishap at the field and there were some damages to some parts. The firewall is cracked, or rather split along the ply joint. Will it be good enought to epoxy the ply together?

The cowl has some cracks and some paint has chipped off. I will reinforce the inside with light fiberglass, but what type of filler and paint should I use to touch up the outside?

Thanks for all the suggestions!

[jack01]

Honestly, on a paint chip that small, I would find a sticker to put on there. Since it's right in the middle of a large area of yellow, it's going to be hard to "touch up" a crack like that and have it look good. To fill the hole, epoxy and lots of micoballoons should work.

I had to fix the firewall on my Edge like this once.

1. Wick in some thin CA and then immediately clamp it tightly together again. Finding a place to clamp it might be a pain, but it's doable.

2. Remove those wood screws and use hardwood dowels to pin it where the screws were. You'll probably have to drill it out a little bit.

3. If it's not already in there, put some hardwood tri-stock behind the firewall where it joins the motor box.

4. On the front side of the firewall, pin the firewall into the hardwood you installed. The trick here is to install two or three pairs of pins drilled at opposing angles. You don't want them straight in. By drilling the holes at opposing angles, you're giving the pins shear strength. If you drilled them straight, the firewall could basically slide off the end of the pins should it ever start to let go.

[rcflyer]

Thanks Jack. The reason I made the top plate of the firewall removable is because it is difficult to accesss the locknuts behind the firewall. Do you think the locknuts are necessary? If using loctite, and spring washers is sufficient to prevent the bolts from loosening by vibration, then I can do away with the locknuts, and glue the top plate permanently to the firewall.

[jack01]

Ah, I didn't know the top plate was removable.

I think you would be just fine with blind nuts instead of lock nuts. I've had planes setup both ways, and never had a problem.

If you do want to have a hatch up front though, you could cut a hatch in the top plate, but still have it solid all the way around the edges. Then glue the top plate down. Just make sure you round the edges where you cut the hatch.

[whidbey1]

Hello
Another way to make the motor box rock solid is to fiberglass the outside of the box with a strip of glass and slow setting epoxy. Works well for me.

Thanks

Bill