Recently had an opportunity to remove the "firewall insulation" from an RV-7A. Although I can't determine a particular brand, the material type is common enough, a fiber mat backed with a fiberglass net and aluminum foil. It was a popular option 20 years ago, and I still see it under panels at fly-ins.
Trouble is, most of the fiber mat products are recycled polyester, Eco Fi being the major brand, and highly flammable, even when treated to be fire retardant (i.e. fire self extinguishes after the heat source is removed). I've tested similar materials and posted photos in the past; they were all uniformly awful. However, obviously not everyone got the memo. Here it is again...
An engine compartment fire heats the firewall. The red hot firewall ignites the insulation, bringing smoke and flame into the cabin. It is a fire transfer mechanism.
I had the firewall test rig set up anyway, so I ran two samples for video. Here's one of them: https://youtu.be/uwax7WNNKow. It was the least flammable fiber insulation yet tested.
There is no good insulation for the cabin side of a firewall. For any given heat source, even a completely inert insulation hastens the rise rate and increases the ultimate temperature of the firewall structure. In the case of an RV, the rivets and aluminum angles melt at 1100F.
Either insulate the engine side, or don't insulate at all.
.
Trouble is, most of the fiber mat products are recycled polyester, Eco Fi being the major brand, and highly flammable, even when treated to be fire retardant (i.e. fire self extinguishes after the heat source is removed). I've tested similar materials and posted photos in the past; they were all uniformly awful. However, obviously not everyone got the memo. Here it is again...
An engine compartment fire heats the firewall. The red hot firewall ignites the insulation, bringing smoke and flame into the cabin. It is a fire transfer mechanism.
I had the firewall test rig set up anyway, so I ran two samples for video. Here's one of them: https://youtu.be/uwax7WNNKow. It was the least flammable fiber insulation yet tested.
There is no good insulation for the cabin side of a firewall. For any given heat source, even a completely inert insulation hastens the rise rate and increases the ultimate temperature of the firewall structure. In the case of an RV, the rivets and aluminum angles melt at 1100F.
Either insulate the engine side, or don't insulate at all.
.
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