Matt's RV-7 Project

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:

Here are the rudder pedals, with all the different pieces either primed or powder coated and riveted together.

I clamped some lumber to the bench so I could hang the pedal weldments in their natural state. Here I've temporarily bolted in one set of pedals and brake master cylinders. You can see that when the pedals themselves are lined up, the vertical parts of the weldments are not parallel, because of the way they're mounted.

One of my weldments seems to have been made a little crooked. When the pilot's pedals are lined up, the copilot's pedals are off by about 1/2". I figure this is not worth worrying about – I'll just build it so the pilot's pedals are straight, and the copilot will be the one who has to deal.

I stole Checkoway's method for marking the location to drill the hole for the bolt that attaches the brake master cylinders to the pedals. With everything aligned and clamped in place, I used a short drill bit to scribe a reference line. Then I took everything apart to drill and deburr the holes. Doing it that way was a lot easier than trying to drill everything in place.

Here's a bottom view of how the brake cylinders attach to the pedals. The plans show a stack of four washers and tell you to use however many are necessary to make the cylinders line up. Four seemed to work out just fine for me.

Another view:

Here's one of the side bearing blocks in which the rudder pedal tubes pivot. You can see I've already drilled three sets of mounting holes (the forwardmost and rearmost positions share a central hole in common). This is to allow customization of the seat-to-pedals distance, but if my experience with the RV-9A is any guide I'll probably just bolt them in the forwardmost position and leave them there for all time. I used the angle drill with a longish #12 bit to make these holes.

I trimmed a chunk out of the center rudder pedal brace in order to clear the firewall recess, and drilled the holes that will mount it to a firewall stiffener. I also drilled the bolt holes in the center bearing block and then split it lengthwise so it can be installed. My bandsaw with the metal cutting blade didn't like cutting the UHMW very much, but a regular crosscut wood saw went right through it.

I match drilled the pilot holes I previously drilled in the center brace into the firewall stiffener with the angle drill. You could probably build a whole airplane without one of these, but I wouldn't want to try.

Drilling the center bearing block to the brace involved a lot of fitting, clamping, and removing the assembly from the airplane in order to drill from the back side. This might have been easier with a slow build kit but it turned out okay.

I put some lightening holes in the brace and marked some areas for trimming. You can also see from the hole pattern that the hole spacing on the center bearing block is different than on the side blocks, so the center hole can't be reused. I wonder why they did it that way? Oh well, at least I didn't have any edge distance problems with any of these holes.

Here's the final version of the center brace after being trimmed and filed.

The rudder pedals are now ready to mount in the airplane, except first I need to put cotter pins in all the castle nuts. I also need to order some shorter drilled-shank bolts to use in a couple places where the plans called out a bolt that was way too long.