Firewall insulation started

Now that all firewall attachments (holes, doublers, nutplates, etc.) are done, we finally started the firewall insulation, using the fiberfrax+titanium foil method that's documented in many places (here, here, here/here/here). We started by taking a mold of the firewall and cutting 3 strips of titanium to be attached vertically, the center one having folds and cuts to fit into the recess: 

Taking a paper mold of the firewall for cutting titanium

Measuring the cuts on the center part of the firewall titanium

3 parts of titanium foil covering the firewall (not final-trimmed yet)

We left about 1.5" of overlap between the center titanium foil and each of the other two - could've been just 1", but I wanted some room to have rivets holding it down without hitting the flanges that are against the recess on the inside.

The Fiberfrax, in addition to its impressive thermal conductivity (or lack thereof), turned out to be a very easy, mat-like material:

Roll of Fiberfrax

To attach it, we cleaned the firewall with acetone, marked areas where we didn't want the fiber (basically places where some part contacts the firewall), then spread drizzles of Firebarrier 2000 on the rest, and especially near the edges of where the fiber would be - then we cut out the unwanted parts with an exacto knife (again, the Fiberfrax is very easy to cut, it doesn't tear if you're careful):

Applying Firebarrier 2000 to the firewall, to attach the fiberfrax

Fiberfrax attached to bottom part of the firewall, minus cutouts for firewall components

At this stage, we also had a circular dependency - that we wanted to rivet the oil cooler mount (section FF1) and attach brake hoses (section 38) near the firewall before attaching the panel (section 41), but also had to insulate the firewall before riveting the oil cooler mount - by simply doing the bottom-left part of the firewall first, then riveting/attaching hoses and the panel, then insulating the top part of the firewall:

Bottom-left section of the firewall insulation attached in place

I'll be posting separately about those sections, and the next step on this section will be attaching the rest of the titanium foil and top part of the fiberfrax.

Time lapse:

Total engine mount and landing gear time: 32.7h

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