Installing the firewall.
In section 23 I mentioned you need to leave the wooden fairing spacer in place. This is why! Without it, the firewall pieces are not the right shape and won't fit. Which I didn't realise so I experimented by trimming off about 2mm from where the firewall pieces meet the top of the engine mount thinking it might shift into place. It still didn't make sense so it was time to email Eddie the Engineer at the factory. He then told me the fairing spacer should still be in place. Oh and you can trim the edges a bit but whatever you do don't trim off the part of the firewall piece that sits on the engine mount as it helps keep the fairing in shape when the spacer is removed! DOH! I came up with a solution to fix my screwup however and checked with Eddie to see if it was ok. Pretty simple, I just made a shim from some aluminium angle and pop riveted it place. I used some epoxy putty behind to hold it in place while I drilled the holes for the rivets. And from the front when it was fixed in place I used epoxy resin in all the seams to finish it off. Stronger than the original design I reckon 🙂
When riveting the firewall pieces in place, I found one or two of the holes I drilled didn't hit the inner lip, or was very close to the edge. So instead of the little washers supplied, I used some of that ali angle to make some 'mudguard' washers. Talking of washers, some of them were really hard to get in place. See my special tool 😄
Note in the pic of the attached firewall pieces I filled in the edges with some Sika fire retardant silicon, from Bunnings Aerospace. Will it help? Who knows. But I figure it will at least help take some of the stress off the rivets.
Last pic is of the finished flame retardant foil/fibreglass. I used water based contact adhesive purely because it is rated for 160 C while the regular stuff is rated for 130 C. Again, will it make a difference when the fuel fire is 1600 C or whatever? Who knows. But 1600 C on one side of the fire retardant material will be much lower on the other side, so that could buy me a few more seconds! I have decided to try hard not to have an engine fire 😄