Firewall Perimeter Seal

[DanH]

What do ya'll like for sealing the perimeter of the firewall? Orange silicone and proseal are obvious possibilities, but has anybody tried a fire-rated product?

[Gsuit]

This is what I used. To quote straight from Van's site:

CS 1900 is a compound for sealing firewall structures. It is elastomeric at operating temperatures from minus 65 degrees to plus 400 degrees F and able to withstand flash temperatures of 2000 degrees F. This product can be used as a perimeter firewall seal on existing aircraft or during construction of new aircraft. In new aircraft, as the skins are being installed, the flange of the firewall should be coated with a thin layer and the skin riveted on while the material is still uncured ("wet"). (Limited shelf life of approximately 4 months from purchase).

http://www.vansaircraft.com/cgi-bin/...product=cs1900

The Tank Sealant Dispenser is basically a caulk gun. I could measure the diameter of the plunger for you and I'll bet it's the same as a Home Depot caulk gun.

[scard]

Fire caulk from ACS.
http://www.aircraftspruce.com/catalo...l2000caulk.php
Probably also available from building supply places.

[lostpilot28]

Quick question guys, is it mandatory to seal the firewall?

[DGlaeser]

You want the firewall to be a pretty effective barrier in case of fire up front, and in general to keep heat and fumes out of the cabin even under normal circumstances. At the very least, I'd put a bead of hi-temp RTV around the inside of the firewall.
Just my $.02

[DanH]

<<...is it mandatory to seal the firewall?>>

I think so. My QB -8, for example, has several dozen "holes" around the perimeter, really the ends of the notches between each bent firewall flange. It needs a bead of something around the perimeter, because....

(1) Small holes allow significant noise transmission.

(2) Our typical exhaust pipe is slip-jointed and may leak to some degree. If cabin pressure is lower than cowl pressure, the unsealed holes become a carbon monoxide path.

[n8zg]

Dan -

I used a fire-stop caulk I found at Lowe's.
I think it was a DAP product.

http://www.dap.com/product_details.a...183&SubcatID=2