Today I checked a very critical item off the list, aligning and drilling of the firewall assembly. First I had to trim the longerons to the correct lenght, ¾” behind the forward edge of the sideskins. After marking, I used my die grinder with the cutting disc to cut them. Unfortunately I had to trim of another 1/16″ off, to make the firewall fit correctly.
Then I had to make 4 attach strips, that attaches the F-704 bulkhead to the longerons.
After clamping the firewall assembly to the longerons and sideskins, I marked the centerline on the firewall lower stiffener. I found this precision compass, which works great for drawing centerlines.
Now I could fit the forward bottom skin…
After a bunch of adjusting and finetuning the position of the firewall assembly, I drilled it to the longerons and skins.
…a look inside, the longerons have been matchdrilled to the firewall steelbrackets. Later on the engine mount will be bolted to these brackets. The landing gear then bolts onto the engine mount.