Category Archives: Firewall

Engine Hanging Prep

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Time: 2 Hours

In prep for my eventual engine hanging I’m working on attaching anything I can to the rear accessory section of the engine. The space is pretty tight back there after the engine is installed so doing them now is advisable from what I have read. One item is the propellor governor. This controls the pitch of the propellor blade via a cable control in the cockpit. It’s bolted with four bolts and torqued to 180-220 in/lbs. The governor has small screws around the perimeter that allows you to “clock” or rotate the inner part to allow the arm to move to a position so the cable gets full range of low and high pitch on the prop.

I will safety wire the screws again once the engine is mounted and the cables measured so that it is clocked just right. I also put in the Dynon oil temp sensor in the oil filter adapter.

Like the back of the engine I also wan to put as much on the firewall as I can. I bought the Raven inverted oil system with my engine and installed the oil separator and valve on the firewall. I spent a lot of time and photos looking at RV-8’s in OshKosh over the last two years to determine where I wanted to mount these.

I just have a few items that I want to take care of before the engine is on but needed to order some parts from Vans first. Hopefully they arrive before next weekend otherwise I’ll be working on those with the engine in place.

Pro-Sealing

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Time: 3 Hours

I removed the canopy structure and flipped it over into the cradle. I have a slight “squeak” when the aft section of skirt moves. It sounds like it’s the fiberglass skirt rubbing or moving ever so slightly on the canopy. So I decided that I would fill the gap between the skirt/canopy and the canopy/frame with pro-seal. I taped it all off to protect the areas that I didn’t want to get a mess on. I also taped of the inside of the forward baggage area were the top skin meets the firewall for sealing that gap while I was gonna have the pro-seal out.

I bought the premeasured type from Aircraft Spruce that fits in the special gun.

After the required mixing I went to it making sure I had all the required items out for clean up including the MEK and tons of rags…this stuff is messy!

With a quick pull of the tape while it was still wet I had nice clean lines. Hopefully the squeak will be gone once this cures in a few days.

ADHARS and GPS Antanae Shelf

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Time: 8 Hours

My last post had some fairing work and it turned out so-so, I’m not an artist by any shot and this will have a lot of work needed. 


I moved on to getting my ADAHRS mounted in the tray I made for them. I just needed to get them lined up with the axis of the airplane and attach them with non-ferous screws, I went with nylon screws and nuts with a little vibra-tite thread locker. 

I then connected the three lines between the two ADHARS. White is for static air pressure, blue is for pitot or ram air pressure and green is for AOA (angle of attack). I had already ran the Skyview network cables to the shelf area but needed to run the OAT (Outside Air Temperature) probes, one for each ADHARS. These will allow the units to give accurate readings with respect to airspeed. You need to keep the probes out of direct sunlight and away from any exhaust so I decided to put them under each wing. I placed them close to the access panels and in the same spot on both wings. 


With all the wires run I climbed into the tunnel to put the shelf back in place and make all the connections. I forgot how tight that space is and what a pain it is to work back there. So I powered up the Skyview and all worked perfect and crossed checked the two ADHARS units with no errors. I decided that I wanted to put my two GPS antanaes under the engine cowling and out of sight after talking with several builders this year at Oshkosh. I took some photos of a really nice setup and decided to replicate it. I started with a cardboard template. After I was happy with the shape and layout I transferred the dimensions to some .032 sheet and cut it out. I drilled all the holes for the mounting hardware as well as some lighting holes. I grabbed the two antanaes and mocked them up so I could drill the attach holes. I also drilled all the holes for the nutplates and dimpled them.I cleaned up all the edges and scuffed all the surfaces to be primed and painted. 


In between the priming and painting I worked on the firewall pass thru. I came up with the perfect spot on the right side of the firewall so that wires that needed to go to the engine area would run nicely.  I drilled a 3/8″ hole for a punch bolt to go through, I bought this tool just for this task. It is two peices that get pulled together and cut thru the sheet. It made a clean and perfect hole and was a lot easier than drilling the stainless steal. I used the pass thru as a guide and drilled the attach holes. After they were drilled and deburred I put the screws in and slid the fire sleeve on. I will run my wires thru this and seal it up at a later date when all the wiring is done. 

Vans had prepunched 3/4″ holes, one on each side, that I was originaly going to use but they are just to close to the edge of the firewall and I think they would be in the way of the Skybolt fasteners I’m planning on using. That was the main reason for switching to these firewall pass through from Cleaveland Tools. So what to do with the holes that Vans punched? Well after a little research I decided on using two large washers and a bolt/nut to sandwich the firewall between them. Once the paint on the GPS shelf was dry I bolted it in place. 

I’m real happy with how it turned out and have Bob M. to thank for the inspiration. One last task for the day was to clean up the wiring in the battery compartment since I’m done running grounds and wires through the firewall, at least on the right side. I have a little more work straighten out the ground wires, but I’m happy without turned out!

Fiberglass Tasks and Engine Mount

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Time: 4 Hours

The next little (relatively speaking because I hate fiberglass) task I want to finish up before getting too deep into the finish kit are the rudder bottom cap and the HS tips. The rudder bottom had one side filled but not sanded so that’s where I started today. 

I used various tools like the finish orbital sander and my new fine work sanding sticks I got from Cleaveland Tools at OshKosh. 

These tools allow me to get into the sharp corners and get a nice clean edge. 

I used them to get inside the HS tips as well. 

So once I finished that little bit of sanding, there will be tons more, I decided to venture into the finish kit. I decided to do the engine mount first since I had just taken the top skin off to work a little easier on a wire. With the skin back off I have good access to the firewall where the mounting bolts go. First up was to enlarge the holes I drilled way back when building up the firewall and forward area for the 3/8″ bolts. 



I used good drill bits and plenty of Boelubewhick helped to drill though the tough stainless steel. Even with that I had a nasty burr on the stainless. The best way to clean that up was with a Dremel and a carbide tip. Once those were done I put the engine mount in place with the bolts, washers, nuts and a temporary cotter pin. Surprisingly it fit perfect without having to tweak steel at all!

She’s on her Legs!

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Time: 8 Hours

So this post is for a few days worth of work over the last week or so since I got back from vacation/flight training. I got back to work in the Hangar this last weekend and the first task was to torque the 9 bolts/nuts on each gear leg. My buddy Glen helped out with this difficult task. The hardes part was getting to the 2 NAS nuts that reside on the outboard bracket of the hear tower. These are in a very tight location and make for fun time working on them. You remember the gear tower mod  I did way back when, well it was for just this task. I found that removing the 2 screws that reside just above these nuts made it a little easier to get the socket on them. After a couple of hours we had all tightened and to their specs. The NAS nuts needed to be set to 240 in/lbs and the rest were to their required bolt specs. The two NAS bolts tighten down the U shaped bracket that holds the outboard section of the gear down. The strength comes from the bridge section of this U shape. So you don’t want the outer legs of this bracket to touch the wear plate before you reach the 240 in/lbs torque. Vans says a minimum .030in gap is allowed. I have read where builders actually had to grind the brackets a little to prevent them from bottoming out before the torque was reached. I did not have this problem, the problem I ended up with was I didn’t get the recommended 1.5 threads showing above the the nut. I got 3/4 to 1 threads showing with the proper torque.

      

      

Now that the RV was on its new legs I decided to tackle the firewall edge sealing. If you remember a post when I reviewed the forward side skins you were supposed to put a layer of ProSeal along the corner of the firewall to create a seal so gas, oil and fumes don’t enter the cabin. I thought this would end up pretty messy and thought I could do a better job later in the build. That time was now so I grabbed the new items I bought just for this task. I ordered a 4″ x 3/16″ nozzle from Sky Geeks website and a tube of ProSeal from Aircraft Spruce.  I clipped the straight end of the nozzle to a 45° to make the application a little easier.

Here you can see the light shining thru the holes in the relief notches in the firewall. This is looking forward from inside the cabin.

I used the Semco gun to lay a nice clean bead of ProSeal along the seam from top to bottom thanks to the small thin nozzle.

  

The next day I grabbed the Andair fuel valve and the structure I built to support it. I left the inboard 2 holes at 1/8″ as I knew that the placement would move a little after the side skin was riveted in place. After placing the structure in place the holes were pretty close, so I open them up with the #19 drill bit for #8 screws. Now that those holes were matched I remove the structure and put two nutplates on the ends of the structure for the new holes. I also countersunk the holes on the left cabin mid braces to accept the #8 screws holding this structure so that they would lay flush.

  

I then finished replacing the fuel system parts that were removed to rivet all the skins.

I also put the battery rack with its support parts in place.

  

To continue with the build you start with the cockpit rails (sills) and rivet them in place. I had painted these prior to heading to flight training but they got a little fuzzys on them. So I sanded them and repainted them last week. As soon as I sprayed them they bubbled up and created orange peel. I have no idea why Rustoleum does that after 2 weeks but it did. So I grabbed the MEK and stripped them bare and restarted. So they turned out great this time and will let them cure for several days before riveting them. So I skipped ahead to the next steps which are the two seat back structures. I started with the forward seat back and separated all the parts followed by deburring all the edges.

  

The two holes at the bottom of the seat back are for the seat belt attach points to stick thru. You have to remove part of the tabs that are inside of these holes.

I then scuffed, cleaned and primed the parts. I will rivet all the parts together next. These parts will not be used in the final airplane as I plan on using an after market interior by Clasic Aero which incorporates this structure inside its seats. But I will have these to put in during aerobatics when I will be wearing a parachute and need the extra room eliminating the cushion on the back. These seatbacks attach to the floor with a hinge, so removing the hinge pin allows for the back to be removed very easy.