Sun Jun 14 2009

Sealing firewall

Well, today I decided to bite the bullet and get the firewall sealed up. First thing was to cleco upper firewall weldments to the longerons to stabilize the firewall while I had it un-clecoed.

Next, all the clecos had to come out.

The side skins were easy to prop away from the firewall using a single cleco.

This should give excellent access for applying a bead of sealant to the side flanges of the firewall.

Here's the firewall sealant. The ratio says 2.5 parts per 100, but I've got no scale to measure this out. I guess I'll just wing it.

I used a bunch of blue masking tape to mask off all except the aft-most part of the firewall flanges.

In the lower corners, I also masked an area for a fillet of sealant.

Wow, this stuff is thick! It's about the consistency of play-dough.

The hardener, on the other hand, is as thin as water. And it smells nasty.

After mixing up a batch, I smeared...err...scratch that...I troweled some sealant onto the flanges, then peeled the tape off. Wouldn't ya know it, the sealant came right off with the tape. I was afraid that might happen.

So, I cleaned everything up, re-taped it all, and mixed up another batch.

This batch, however got massively thinned with lacquer thinner. It took probably 15 minutes of constant thinning, stirring, and thinning some more until the stuff was roughly the same consistency as proseal.

Once thinned out, it went on much better.

And the tape peeled off nicely leaving a relatively uniform bead near the aft edge of the flange.

I also got the fillet in place at the lower corners. Not as pretty as I was hoping for, but good enough.