On my 360, I originally installed the stainless firewall with three layers of fiberfrax. Then I looked at Angier Ames’ airplane with the quilted firewall blanket and decided I had to do the same. I wasn’t flying yet, so changing the firewall was pretty easy.
Cost from Lancair used to be $300, is now $510, but Hi-Temp in Camarillo CA was a supplier at the airplane company I worked for then so I was able to buy for $250.
I kept track of component weights, and my final result was that the firewall blanket is 3 pounds lighter than the stainless / fiberfrax. (Part of this savings may have come from replacing the two steel area washers under each engine mount pad with aluminum area washers, so it’s not entirely apples to apples. I don’t have the numbers anymore so I can’t verify this.)
I have attached a picture of the firewall with phenolic spacers attached. I also included a picture of the back side of the blanket, where I cut out the insulating material around each spacer. I used red RTV to seal the blanket there and around the outer periphery. Finally, I have included a picture of Angier’s firewall. (I couldn’t find the picture of mine. It looks the same.)
Steel protects the plywood from direct flame. The fiberfrax protects the plywood and it’s reinforcing fiberglass from heat. The quilted blanket can do both. Lighter, easier, and it looks better. (Strictly speaking, the steel/fiberfrax, or the blanket, is the “firewall”. The plywood bulkhead that we call the firewall, well, that’s not the right term for it, but we all use it. Its proper name is probably "forward fuselage bulkhead", but you have my permission to "whap me upside the haid" if I ever call it that.)
With either approach, you need to make sure there is no crushable material under the engine mount. I extended this concept to *every* firewall penetration but it is not critical except at the engine mounts. Usually I glued a piece of phenolic to the plywood bulkhead equal to the thickness of the blanket. Under the engine mount I used the area washers. Under the nose gear “doghouse” I used metal sleeves from Ace Hardware. All fasteners except for the engine mount bolts go into Click-Bond nutplates on the aft side. The blanket is tacked into place with red RTV, is actually held into place by everything bolted onto it, and sealed around the outer edge with red RTV.
Hope this helps.
- Rob Wolf
Old School LNC2
Parker CO