This is the second installment for the construction of the Upper Fuselage on my RV-12 aircraft. There is a GOTCHA that I didn't catch until sometime later. It was fixable but the time to catch it is now!!!
GOTCHA Here it is in all it's glory. This screw hole is for a #8 screw. Dimple it before installing the upper firewall on the plane! There is one hole on each side of the aircraft. I didn't and had to build a special dimpling die to fix it later.
Step 1: Smear a thin layer of fuel tank sealer on the uper surface of the bottom flange of the F-1201A Firewall Upper.
Rivet the Assembly to the fuselage assembly.
Step 2: Match-Drill #30 the Mid Cowl Hinges to the Firewall Spacers and Side Skins.
Step 3: Cleco then rivet the two Mid Cowl Hinges to the Firewall Spacers and Side Skins (with the manufactured head on the exterior).
Step 4: Dimple the nutplate rivet hoes in the nutpaltes, then rivet to the F-1201A Assembly and fueslage assembly as shown in figure 1 on page 29A-03 of the RV 12 aircraft plans.
Step 5: Cleco then rivet the Forward Skin Stiffeners to the F-1201A Assembly and the Fuselage Side Skins.
Step 6: Actually completed on 7/10/13) Fill the #11 tooling holes in the Firewall Upper with Firewall Sealant. Add a bead of Firewall Sealant around the perimeter of the firewall parts. Use a Popsicle stick to form a smooth fillet. Make sure all pages from the bend relief notches along the flange and in the corners are fully sealed. Use a light on the forward side of the firewall to help verify that the full perimeter of the firewall is fully sealed.
Builder's note: Firewall sealant is just strange stuff it is not like fuel tank sealant. It's kind of a cross between black bubble gum and wetsuit material. It is NOT the same as fuel tank sealant (which burns readily when exposed to a flame source even when dry.) Firewall Sealant skins over very fast and has a short work handling time.
I cleaned the primer of of the fuselage skins with MEK and added two stripes of electrical tape keep the edges clean. I purchased the pint can of Firewall Sealant and used a plastic syringe to create the fillet.
This completes page 29A-03. Please don't forget about dimpling those two screw holes! And with that I will leave you to ponder Firewall Sealant.
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