Matt's RV-7 Project

This morning I finished up the center section cover and related parts. I riveted the two nutplates to the stainless firewall recess where the center section cover is screwed in place. Usually for nutplate rivets I've been lightly countersinking and using NAS1097AD3 reduced-head rivets, but the stainless is way too hard to do that easily. Instead, I dimpled the steel for regular AN426AD3 rivets and used these cool nutplates with dimpled ears, which I found in a box of junk left over from a previous project. I think I may have picked them up at the local aircraft parts store at some point. You can kind of see the dimpled ears in this photo if you look closely.

The fuel selector housing gets nutplates too:

Since I had it in hand, I also decided to fit the fuel selector mounting plate for my Andair fuel valve. I had one of these on my last RV and it was very nice – the stock Van's one is perfectly servicable, but it looks like it came off a garden hose.

I cut off the part of the mounting plate that's only used with manual elevator trim, and drilled the 1" diameter hole for the valve body with my MOAUB.*

* Mother Of All Unibits

I back drilled through the valve's mounting ears into the plate for the bolt holes. Luckily they didn't overlap either of the holes that were pre-drilled in the plate for Van's brass valve. Here's the cover plate being test fitted.

Here's the fuel valve temporarily installed in its home on the front of the spar. Ooh, shiny.

Today's job was the center section cover. Here it is being test fitted, along with the access plate that screws to it:

Here the heat baffle is being fitted for riveting. The hot air from the heat muff passes through the firewall behind the upright part of the center section cover, and this piece keeps the hot air from going down inside the tunnel – it's forced out through the louvers instead. I decided not to prime any of these parts, since they're removable.

I bent the louvers outward as directed by the plans. Actually I used a different technique than the plans call for – they say to clamp a piece of angle across the bend line and use your fingers, but I found that this material was too thick to make good looking bends by hand. So, I clamped a piece of angle across either face of the bend line (important to prevent a sloppy bend) and grabbed the louver with my hand seamer to make the bends. It worked pretty well.

Then it was an eternity of deburring – the center section cover has a lot of edges that need to be smoothed.

Here's a trial fit of the fuel selector housing. There is a small (3/16") gap between the fuel selector cover and the aft edge of the center section cover, but I couldn't move the center section cover any further aft and still get the flange that attaches it to the selector housing to line up. This will probably be invisible anyway.

I know the fuel selector mounting plate is on upside down in this photo – I'm going to cut off the bent tab anyway since I have electric elevator trim and don't need it to mount the manual trim knob.

The plans call for 15/16" spacing between the floor and the center section cover, and suggest using a "simple wooden spacer". I didn't have any wood of the proper size, but I found these nuts that had the exact right outside dimension. Good enough.

I lined everything up and drilled the holes where the center section cover gets attached to the floor stiffener with screws.

Oh, rats – I somehow let things get out of whack when I drilled the center section cover to the stainless firewall recess, and these two holes ended up in the wrong spot. You can just barely see in the photo that the holes in the recess are about 1/4" too high. Dang. I thought about ordering a new firewall recess piece, but I didn't want to pay twenty-five bucks just to fix two misdrilled holes. Hmm…

What I did instead was fabricate and rivet this trim strip to the top of the center section cover, and back drilled into it through the misplaced holes in the firewall recess. Now everything lines up, and this will be invisible once it's all painted. Problem solved. The rivets that attach the strip to the cover and squashed extra flat so they won't interfere with the lower edge of the firewall recess; this isn't structural so it won't matter.

Okay, back from Sun-n-Fun and the bandsaw is repaired. Time to make the brake doubler plate for the firewall:

And, here it is much later, riveted to the firewall:

While I was waiting for Mary to have a chance to come help buck the rivets that secure that thing to the firewall, I busied myself with fixing up the flap bearing blocks that go on either side of the F-705 bulkhead: