Dynamat on Firewall

[lr172]

I am tidying up the interior components before I do electrical and hang the engine. I bought some dynamat for the cabin side of the firewall to deaden some of the noise and vibration. However, I did some research and it seems that some recommend against anything on the f/w that can burn. I read a post where some guy burned it and it didn't support a flame or smoke much.

I am guess on the general wisdom here. I'll accept a pound or two of weight to kill some noise, but don't want a safety hazard.

Can anyone offer some guidance here?

Thanks,

Larry

[Don Jones]

Here is all the reading you can stand concerning firewall insulation.
I went with the ceramic blanket completely encased in aluminum foil and mechanically attached it to the inside of the firewall using a safety wire system.

http://www.vansairforce.com/communit...all+insulation

[DanH]

Originally Posted by lr172

I bought some dynamat for the cabin side of the firewall to deaden some of the noise and vibration.

Larry, I don't recall ever testing Dynamat, but I did put at least one other rubber "firewall insulation" on the burn rig. I think a butyl rubber sheet would be a very poor choice for the cabin side of a firewall.





§ 23.1191 Firewalls.

(f) Compliance with the criteria for fireproof materials or components must be shown as follows:

(1) The flame to which the materials or components are subjected must be 2,000 ±150 °F.

(2) Sheet materials approximately 10 inches square must be subjected to the flame from a suitable burner.

(3) The flame must be large enough to maintain the required test temperature over an area approximately five inches square.

(g) Firewall materials and fittings must resist flame penetration for at least 15 minutes.

§ 23.1182 Nacelle areas behind firewalls.

Components, lines, and fittings, except those subject to the provisions of §23.1351(e), located behind the engine-compartment firewall must be constructed of such materials and located at such distances from the firewall that they will not suffer damage sufficient to endanger the airplane if a portion of the engine side of the firewall is subjected to a flame temperature of not less than 2000 °F for 15 minutes.