Category: Firewall

ELT Wiring and some other things

March 21, 2021 – I made the wiring harness for the ELT.

The connector that came with the ELT was a new one for me. The pins are solder cups, so the wires are soldered into the connector. I’d never dealt with this before but it was fairly simple. I ran a shielded 3-wire bundle through the airplane to check for length, then pulled it back out and terminated the ELT end.

I added a nutplate to the ELT mounting bracket, and made a bracket one bulkhead back for a clamp so I could secure the antenna coax.

Then I riveted the antenna doubler and installed the antenna.

On to some other items…

Airport friends came back and we pulled the wings again so I could finish what had to be done before permanently installing the wings next time.

I also installed boots on the battery cables and installed the hold-down bar.

Time: 18:00

Continued various Firewall Forward items

February 2, 2020 – I continued work on securing firewall forward items.

I ran the line for the mechanical fuel pump drain. This will vent through the lower cowl, a short distance from the exhaust.

I secured the Red Cube.

I installed the sniffle valve. Not sure how this is going to work out, though, because of its proximity to the exhaust.

A friend came by and helped me secure the clamp for the oil breather tube.

We also pulled the manifold off the firewall so I could replace a 45-degree fitting with a straight one. Maybe sometime I’ll get smart and put nutplates on this…

Time: 2:00

Moved Throttle Cable

February 2, 2020 – I moved the throttle cable at the firewall so it will come through the cabin heat box at a better location.

I loosened the eyeball in the firewall and turned the cable straighter. The first picture shows the upward orientation of the cable. The second shows how the cable will enter the cockpit through the access panel in the heat box. I’ll put a grommet in that panel later.

Time: 1:10

Closed firewall and installed engine mount

February 2, 2018 – I found somebody available to help me rivet the firewall recess.

Before I installed the recess, I had to finish installing the rudder pedal center bracket.

I also had to install the two nutplates in the recess where the cockpit heat box attaches.

One of my EAA 168 buddies came over and we riveted the firewall recess.

I applied firewall sealant and clecoed the recess in place.

We got the recess installed, then decided to go ahead and install the engine mount. Jim shot the recess rivets outside, so he wanted to crawl in and do the bolts for the mount.

Time: 1:30

Forward skin installed

November 11, 2016 – Wow! I guess I haven’t done any updates in a while.

I’ve been working towards getting the windshield installed. I wanted to install fans to help cool the avionics behind the panel, so I cut those holes, then I prepped the glareshield area for priming..

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I then permanently installed the sub-panel structure. I had previously painted it white for possible added light under there.

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I realized that I hadn’t dimpled the flanges of the firewall where the top skin will attach, so I did that.

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I painted the underside of the skin flat black where it would be above the panel, then i back-riveted the attach angles for the panel..

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Time to close up. I shot what I could by myself.


This is where some time got away from me. I had to get help to finish riveting the skin, and during that time we took a short vacation. But I got my friend Wilson to come and help, and we got the rest of the skin shot on in pretty short order.


I cleaned up the glareshield for painting. Had one more day of halfway decent weather before it cooled off and rained for a week or so, so I got the paint done. I found some spray on truck bed liner paint that I thought I’d try. It has a nice texture and is flat. I think it looks nice.

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I had to tidy up a few things: I installed the rollbar brace, and I had to resecure some clamps for the fuel vent lines. I had to move the vent lines so I could rivet in some of those locations.

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Time: 11:00

Continued sub-panel

October 27, 2015 – I continued working on the sub-panel structure.

I needed to locate the center rib against the firewall. There are no instructions or guidance to do this, so I went ahead and drilled those holes. I took the top skin back off and slid the center rib out. I drew a centerline and drilled holes in the rib. I clamped it back in position, put the skin back on,  and drilled the holes through the firewall from inside and underneath.

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Back off with the top skin, I needed to drill the F7108B angle. This is a solid angle that reinforces the center rib. I also drilled a fastener hole where this angle attaches to the firewall.

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I clecoed the actual panel into place.


There are some angles that need to be formed to fit the top curve of the panel. I fluted those, clamped them in place, and drilled the attach holes through the panel.


There are also small angles that hold the panel in place on the outboard corners. The problem with drilling these was that the panel moves, so the angles move. I clecoed the top skin entirely in place, all the way down to the edges. This was a lot of work. I drew lines at the panel edge where it sits on the canopy rails. You can just see the lines against the lower surface of the panel in this photo:


I drilled the entire skin to the structure.

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I also drilled the holes in the top flange of the firewall.


Now that I knew where the panel would be, I removed the top skin. I clamped the angle in place using those drawn panel edge marks as a guide, then I drilled through the canopy rails.

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There are smaller angles that support the panel on the inboard side of the canopy rails. I clamped these in place and drilled the holes for those.

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I pulled the whole assembly off to the table where I will beburr everything.

Time: 4:40

Finished fuselage canoe riveting

June 16, 2015 – I finally got my firewall sealant this last weekend, so I did that first.

I put a pretty good bead all around along the rivet holes. I was concerned that I’d use it all before I got all the way around, but I still had some left over when I was done.

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I clecoed the lower skin in place for good.


My buddy Stan came back over and we shot what was left on the fuselage.

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I had to remove the attach brackets for the sticks so I could get to those rivets cleanly, so afterwards I put those back on.

I put the F728 angle in place, because I didn’t want to shoot rivets in the belly with the canoe right side up if I didn’t have to.


Pretty cool view from under here…:


Time: 5:15

Fuselage parts prep

April 29, 2015 – Spent just a little time today cleaning the smaller parts, angles and bulkheads and getting them ready for paint.

Then I cleaned and dimpled the three skins; the side skins and the lower forward skin.


I also dimpled and countersunk the flanges on the firewall, then I deburred all the holes in the engine mount brackets.

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I dimpled and deburred the outboard seat ribs and the angle brackets in the center fuselage.

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While I was doing some of the dimpling somewhere along the line my vise grip dimpler broke. So I called Avery and ordered a new one…


A friend from work came over and helped me separate the center section from the aft fuselage. We set the center section on the floor, then we rolled the aft fuselage back right side up and pulled out the longerons.

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I deburred and dimpled the skin fastener holes on the forward and aft ends of the center section skin. I’m priming the skin that gets overlapped.

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I removed the forward bulkhead from the aft fuselage to give me access to the fastener holes there.

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Time: 9:20

Started F717 Longerons

March 17, 2015 – I’ve been working on getting the F717 longerons in place for drilling. These are very thick angles. I started out by cutting them to length, then creating a cutout on one end. I drilled a hole for the radius of the cutout, then took them to work to cut on a bandsaw.

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Brought them back home, and used a rotary file, then sanded them down to shape. I just need to do a little final polish after they are drilled.


I had to put a little twist on the forward end so they would fit in the engine mount bracket on the firewall. Today I’ve been working on the right side; I’ll go the distance with that one, then use lessons learned from it to do the left side.

Along with the longerons, there are gussets that help tie the longerons to the firewall.

These gussets get trimmed and then bent to fit the area. I located some fastener holes, then tied the two gussets together (left and right) to try to make them mirror images of each other.

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I took them out to a friend’s hangar where a brake lives, and bent the edges as required. I tried to fit the right one in place, using a 1/8″ spacer to keep it 1/8″ aft of the firewall, as mentioned in the manual.


It will be a challenge to get good edge distance on a couple of the fastener holes, but it works if you just take your time; a lot of fitting, moving, marking, and crouching under the firewall… Here’s the right gusset more or less in place:

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…and here’s the right side view of the longeron and the gusset as it sits at the moment:


Time: 3:05

Fitted firewall

March 5, 2015 – I started today by making the straps that tie the F704 bulkheads to the longerons.

The plans call for .063″ thick straps. I used the four pieces of raw stock I had on the shelf, and cut them to length, then clamped and drilled them.

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I also trimmed the forward ends of the longerons to the correct length. I had previously marked them at 3/4″ from the front edge of the side skins.


I moved on to the firewall. I clecoed the F772 forward lower skin in place.

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The instructions tell you to keep the forward ends of the longerons aligned with the side skins by placing rivets in the holes just as alignment pins, because the firewall is heavy and could weigh down the longerons.

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I drew a line along the bottom structural aluminum angle of the firewall to mark the centerline. This line should be visible in the second row of fastener holes in the F772 skin.


I clamped along the lower edge of the firewall. You then need to verify that the forward face of the firewall is 5/8″ from the forward edge of the side skins. After making sure that dimension is correct, and verifying the alignment rivets could be moved, I drilled both sides of the firewall.

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I clamped the upper engine mount brackets in place inside the longerons. This is where I will drill next.


Time: 3:10

Firewall done!

February 26, 2014 – Didn’t think I’d get to finish this week, but I squeezed in an hour or so of work today and got the firewall done.

I started out by shooting the right side of the firewall, because I’m right-handed and more comfortable with the gun in that hand. Got all of that side done, then moved on to the other side.

Riveting firewall Riveting firewall

Then my lovely bride LJ came out and we shot some more rivets.

LJ and the firewall

We’ve started to do some remodeling in the house, so that has taken a lot of time over the last 2 weeks. We reached a stopping point this afternoon, so I decided to try to get out and maybe finish the firewall. I figured out how to stand the firewall up so I could get good access, and got everything shot.

Here are some of the details:

Fuel pump doubler. The nutplates and shop heads are on the forward side of the firewall.:

Fuel pump doubler Fuel pump doubler

Brake doubler:

Brake doubler

Firewall aft (cockpit) side:

Firewall aft side

Firewall forward side:

Firewall forward side

The firewall recess stays off for access behind the panel, etc.

Now things get really interesting…

Time: 4:25

Painted firewall parts

February 17, 2014 – Today I got all the firewall parts painted.

In my last update I countersunk all the applicable holes to fit dimples in the firewall. Well, when I started polishing those parts, I realized that in spite of my notes written directly on the parts, I had countersunk on the wrong side of one of the corner fillers. So I got hold of some .125″ T3 and made a new one.

New corner filler

I cleaned, alodined and painted all the firewall parts. I used aluminum-colored engine enamel, since these parts can be exposed to higher heat.

Alodined firewall parts Painted firewall parts

Ready for firewall assembly…

Time: 2:40

Firewall fastener holes

February 13, 2014 – I drilled all the fastener holes in the firewall to final size, then deburred the firewall itself.

Then I pulled out the C-Frame and started dimpling the firewall.

Dimpling the firewall Dimpling the firewall

After I got done making noise, I coutersunk all the attaching angles and fillers so they would fit the firewall dimples. I marked holes that are NOT to be dimpled/countersunk, and marked the sides of the fillers where the countersinks would be.

Countersunk firewall parts

I deburred and polished all the edges and corners of the firewall parts. Now it’s time to scotchbrite everything and get them ready to alodine and paint.

Pile of parts ready to clean and paint

Time: 2:50

Made firewall doublers

January 28, 2014 – I drilled up the doublers that go onto the firewall. They are the F-601Z Aux Fuel Pump doubler and the F-601TD Brake doubler.

F601Z Doubler F601TD Doubler

I misread the instructions on the TD doubler, so the attach rivets will be -4s instead of -3s. That’s all I’m going to say about that.

I also clecoed the firewall recess in place and back-drilled those holes to full size.

Firewall recess drilled Firewall recess drilled

Next thing is to back-drill all the firewall fasteners to full-size.

Time: 1:10

Drilled more firewall parts

January 23, 2014 – I slipped out into the garage today to do some more drilling on the firewall parts.

I drilled the other F-601J angle. In my post yesterday I didn’t show the specifics about drilling this angle. According to the plans, it’s supposed to be 3/32″ off the bottom of the angle at the bottom of the firewall. I slipped a #40 drill bit in as a spacer and clamped the angle and spacers in place.

F-601J angle placement

I fit the spacers for the upper engine mount brackets and clecoed them in place. I had to drill two small additional fillers.

Upper mount filler Upper mount filler

I drilled and clecoed the F-601E stiffener in place. Here’s the firewall as it sits right now:

Firewall assy

I still have to make and drill a couple of doublers for the firewall.

Time: 1:00

Continued Firewall parts

January 22, 2014 – I cleaned up the F-601J angles today and I made the F-601E stiffener.

F-601J angles F-601E stiffener

Clecoed most of the firewall parts together and started to drill one of the angles. Had a little trouble getting the stack of fillers and the angle to stay put. I could be happier with one of the holes but it will be fine.

Drilling F-601J angle

Came up against an appointment today, so there will be more pictures of the clecoed firewall assembly later.
Time: 1:30

Started Firewall F-601J angles

F-601J angles cut outJanuary 21, 2014 – I did the first shaping cuts on the F-601J angles for the firewall. I don’t have a band saw, and I hope this was the hardest cutting I have to do. Pain in the *** with a cutting wheel in a die grinder. But it’s done, and now all I need to do is shape and polish. The picture shows them clamped together so I can shape them both at the same time.

It’s good to be back in the factory.

Time: 1:00