Firewall/Tunnel and Brake Lines

Firewall

Per the plans the RV-10 uses a single layer stainless steel firewall with aluminium fittings.  This has been shown to melt fairly quick in the event of an engine fire and once your fittings melt then all that smoke ends up in the cabin.  For you non-pilots that's a very bad thing....

Solutions have been discussed over on the VAF forum and Dan Horton has not only come up with a great solution but has provided pictures and test results to back his findings.  The idea is that doing a little more to the firewall will slow any fire as well as help keep heat out of the cabin during normal flight.

His suggestion is what I went with was to cover the engine side of the firewall with 1/8th inch Fiberfrax and then cover that with some stainless steel foil.  Lastly replace all the fittings with stainless steel versions, secure with stainless steel rivets and caulk seams and edges with 3M Fire Barrier 2000+.  Here are his pictures.

General concept

Since the SS Foil comes in 24inch wide rolls this is how you deal with the center seem.

 This was a lot easier than I anticipated, it's a bit of a struggle to work with the Foil but I was able to get it somewhat decent looking.  The worst part by far is the ugliness of my caulking but going for more functionality on this one. I should also note that I used a thin layer of the 3M caulking as an adhesive, relying mostly on the fittings and the caulking to hold it down.  If it starts pulling at a later day I can add some SS Rivets fairly easily.

Bare SS Firewall

Layer of Fiberfrax with 3M 2000+ applied.

I would say I'm 95% complete with the firewall.  I'm waiting on a back-ordered grommet and some nutplates to finish up the control cable area and to attach the oil cooler.  When I get my engine mount I will mark the locations and actually remove the Fiberfrax and Foil from the attachment points.  This will allow me to attach the mount directly to the original firewall as designed.  I will then apply additional 3M 2000+ around these points as well as any additional fittings I might attach later.

I also decided against putting any type of foam insulation on the cabin side of the firewall.  May sound a bit strange since I'm putting a lot of insulation in the plane, but this has less to do with sound reduction and more to keep the heat/cold in, especially since I'm putting an Air Conditioning in the plane.  I'm also banking that the Fiber/Foil bit helps keep the heat out so my feat don't burn up while flying... and I feel keeping foam away from the firewall will help keep my feet from literally burning in the case of an actual fire, or from passing out to the smoke that I witnessed when I putting a blowtorch to the material.

Mostly finished.

Tunnel

(Update: When I started working through Section 39 and installing the control rods it became obvious I was having clearance issues with my below packets installed.  Concerned about having the controls hang up I decided to scratch what I described below and leave the entire tunnel area bare.  If later down the road I begin to have 'Hot Tunnel' issues I will go back through and figure something out.  My hope is between the firewall side heat shielding, using stainless steel attachments and the new outward facing exhaust that I won't encounter any issues.  Only time will tell...)

In earlier kits there was a problem with the center area of the plane, or what's called the tunnel getting extremely hot.  This actually lead to Vans putting out a Service Bulletin. Their solution talks about adding insulation or redirecting some airflow.

For my build my additional firewall work, sealing around the fittings and using all SS attachments 'should' help keep tunnel heat to a minimum.   I've decided against putting anything that will burn or give off toxic gas, for the same reason I'm not putting foam against the FW. I've also heard that the exhaust system for the RV-10 has changed to direct heat out sideways now versus down the middle of the plane.  In the event that this becomes a problem once I start flying then I will work to solve it then.

Aft of the spar in the tunnel I went ahead and used a method of insulation that I'm comfortable with.  It's a bit of a hybrid with what people have used and wasn't all that difficult.  I essentially encased a layer of Fiberfrax and Foam in a Stainless Steel Foil pouch.  This is the same technique I use to smoke ribs and they turn out fantastic, so why wouldn't that work on an airplane?..

Starts like this....

Ends like this, delicious!!!

Installed in rear tunnel

Brake Lines

Section 36

A fairly common deviation from the plans is to not use the 1/4 aluminium tubing for your brake and fuel lines.  There are some better options out there and I went with TS Flightlines for mine. Tom was fantastic helping me work through my order, answered question and was extremely fast to ship out the product.  On top of that the lines look great!  I was able to knock out the initial part of the install in an evening.  The rest of the lines get connected when installing the pedals.

Anytime you deviate from the plans you'll probably encounter an issue here or there.  My issue was more with the hole in the gear weldment that the NTP brake line fitting exits was a bit too big and I didn't like the way it sat in there.

My solution was essentially make a washer out of some scrap and wedge that inbetween the bottom skin and the gear weldment.  I started with using a 1.5 inch hole saw bit and cut out a couple of blanks.  I cleaned the edges of these and used a unibit to put a larger hole in the middle.  Because of how the fuselage side skin connects I needed to shave a bit off the 'washer'.

"washer"

Final Fit

Feels much more secure

 The rest of the task involves running the lines, connecting them to the various NTP fittings and cushion clamps.

Under front seats

Tunnel

Cabin side firewall

This section was extremely quick, I'm guessing not as quick if you have to bend your own lines, flare your connections ect.  The rest of the Brake lines (as well as the parking brake) will be installed when I do the pedals.

Aileron Actuation

Section 23

I had started this section awhile back but unfortunately messed up on some drilling and ended up with my torque tube lengths being too short.  I could of used washers to make up the length but instead decided to try my hand at some welding at a later date to see if I could fill in the holes. Later came and well, instead of welding the holes I basically blow torched larger holes.  I ended up using the piece to practice a few things and decided I'm not ready to weld airplane parts.  Instead I ordered a new tube which was $20 so not an expensive mistake.

Big Gap

With the new part I was able to catch up pretty fast and get the assemblies installed.  The most difficult part is making sure everything is lined up in the neutral position.  If you mess up here you really might not notice until you're ready to fly, which in that case I'm hoping to get some extra help with the rigging so the plane doesn't fly sideways.

New parts properly clocked

 With aligning both the push rods and the ailerons Vans provides you a jig of sorts to help with finding neutral alignment.  This little aluminium piece jig bolts onto the bell crank allowing you to find the correct position for both push rods. This allows you to adjust the pushrods as needed so they're the correct length when you have both the torque tubes and the bell crank in neutral position.  I should mention that I used a ruler and a clamp to find the neutral positions of the torque tubes. Didn't take a picture but in short you want to make sure you put these in the correct position.

Push rod installed

All in all works out pretty well and I'm assuming during Phase I you can tweak these for 'heavy wings' or other unwanted things.

At this point you install your flaps 'temporarily' to find the correct alignment of the ailerons.  I saw temporarily because the plans do, not sure when you take them back off but I guess I'll find out later.  I had problems finding a particular bushing which required me to do some internet searching.  What I came up with was that they were the 6 bronze bushings provided and labeled differently than the plans.

Flap Bushings

It's a very tight squeeze and read that some people just sanded out the area a bit until they could fit them.  Not liking that approach I instead stuck all 6 bushings in the freezer for about 20 mins to shrink them just enough that I could use a C-clamp to squeeze them on.  Worked out well and then to get about the same 1/32" clearance on both sides I used a large nut so the bushing could squeeze through without smashing it.

I again didn't take pictures of the next part but at this point most builders are used to the method of test fitting control rods, remove, adjust retry.  The key is to match the alignment of the flaps to give a straight edge.  Once you have it you can reinstall everything, torque down the bolts and this section is done.

Doesn't look like much but functioning control services are neat!

Cabin Cover & Engine Choices

Cabin Cover

Section 43

It's the summer time, which means it's hot... excessively hot at times and there are several things that are practically miserable to do in the heat:

1. Eating soup
2. Going for a run



Fiberglass Battle Dress

3. Building a plane in the garage

When it's pushing 100 degrees outside even with an insulated garage and a fan it's still insanely hot.  I find myself grabbing rags and turning them into headbands, unconcerned that I previously used the rag to clean up Acetone.  On top of that my Fiberglass worksuit consists of an old Flight Suit from my sailor days, full goggles, gloves and and some sort of mask.  There's been times I've gone without this only to end up with fiberglass all over the place including my skin. So the unfavorable working conditions coupled with this summer being full of activities I feel like my progress has taken a bit of a hit.  I view it as a balance and as long as I continually make some level of progress then I'm good with it.

This brings me to what I've been working on lately.  I've been working on finishing up the wings control elements and wing tips in conjunction with the cabin fuselage.  Since I've made the most progress on the fuselage I'll write about that.  I decided to skip a number of sections and go to working on the cabin top fitting.  One reason is because there are some elements I'm undecided on for the interior that I want to think about it while I tackle these other things.  Another reason is this is a large piece that was sitting around and I wanted to do something with it.

I've heard there's a lot of angst with the cabin top and while it's not the most enjoyable part to deal with, knowing it's fiberglass and you can always fix it later helps out.  First part you do is trace the scribe lines and then go back and double check the scribe lines because they're not that accurate.

Pre-trimmed piece

 I choice to do the cutting in the driveway using disc grinder and then finished it off a bit with a disc rotary sander using 60 grit pads.  All in all I had to test fit it at least 10 times before I was happy with it and then another 2 times after that because I had overlooked parts.

First Trim

Closed that gap about another 1/16th of an inch.. rest will get glassed over

Once I was happy with my fit I pulled it off one more time to square up the edges per the plans and make sure nothing looked to wonky before I started the drilling.  I was happy to get back to drilling and really this part while a bit time consuming was enjoyable.  You basically put your forward tail skin on and use it as a guide to match drill #30 holes.  I broke all my smaller bits so used a 12" #30 to do this part.  You end up drilling a few, removing clecos and spraying out any material trapped between the skin and cabin top, then recleco and move on.

Action shot!

The step of centering the front brace with the fuselage top was a lot harder than I had anticipated. I tried several methods to center it taking various measurements clamping it in place stepping back, looking at it.. rinse repeat.  In the end it's centered as well as it can be, not sure what other people used but the best method for me was to center a large measuring stick across the front and then center the bar on that.  I'm happy with hot it looks.

So I'm now complete with this section for now.  The rest of the section involves trimming and placing the windshield and rear side windows.  Physically attaching the top along with all the fiber glass work which has to occur.  Because I will be removing the top for the interior, avionics, center channel ect this will end up being one of the last things I do before moving this all to the airport.

Now, it looks like a plane

Barrett Precision Engines

BPE is a shop out in Tulsa that overhauls a variety of aviation engine types for both the Certified and Experimental market.  I happened to be in Tulsa for work and took some time to check out their facility.  Monty and Allen were great and really helpful in showing me around and answering any questions I had.

When I first started looking into engines my kneejerk reaction was to get a brand new Lycoming 540 from Vans and install that.  I had called Rhonda at BPE and she did a good job explaining the differences between buying a new Lycoming vs an overhauled engine.  Essentially the pricing is relatively the same but the big difference is going through BPE you can be very specific on what you want with and done to the engine.  There's some features you can get on an overhauled engine that you can't really get on a Lycoming until after the fact and at that point you'll have some extra parts to sell and some extra costs in having a set of new Bendix magnetos for example installed.

My take away from the trip is I am aiming for a Lycoming 540 with 9:1 compression and most likely their cold air induction system.  The cold air induction system replaces the bottom oil sump pan with another one that has the air intakes on the outside, meaning the hot oil isn't heating up the air going into the engine.  This will make the bottom part of the engine hanging down lower than the standard engine, meaning unless I really want to do a lot of fiberglass work I'll have to get an aftermarket cowl from Show Planes. 

Another option if I decide the cost increase vs performance isn't there then I'll end up getting the same engine without the cold air induction system.  It's still a phenomenal engine but then I can get Rod Bowers ram air kit for both increased performance. An added value to this option is the easier lower cowl removal.  You end up taking the fiberglass cowling piece around the kit off and then the bottom cowling can move out without hitting your 3 blade prop.

Still have plenty of time to make some of those final decisions but bottom line is I'm getting the engine from BPE.

Access Covers and Floor Panels

Section 35

If there's one thing I learned in this section it was that the Pneumatic pull rivet gun is a real time saver. You are still required to use the hand riveter in tight spaces but when kicking out a row of cherry rivets you can roll through them fast, and your hands won't hurt.

You want to make sure your conduit is in place and you know where you're mounting things before you start closing up.  The plans actually specify that you should do your wiring before closing up the panels but since I have conduit I won't need to get into these spaces again.

I also decided against priming and painting the access panels, I may change my mind on some of them in the future but I really don't see the need right now.  These are easy enough to get to that if corrosion does form I can easily replace them.  Aesthetically I'm doing a full interior with carpet, panels, ect so they won't be visible anyhow.  Any of the visible parts I'll end up painting later, ie seat back, baggage area bar.

Final picture with panels and upper fuselage attached

Baggage Door

Section 34 

It doesn't seem like an exciting section, but having a functional door on the plane is pretty neat.  Wasn't overly difficult but had it's own set of challenges.  Ensuring the hinge is lined up takes a bit of time.  Riveting the skin the frame is a bit awkward and resulted in a few smiley, in hind sight if someone would of been there to help me hold it, it probably would of turned out cleaner looking... oh well it's getting painted anyhow.

Inside

Open and Closes

It's done for now, I did go ahead and order locks and door seals.  For the locks I ordered Fort MFW1058 cam locks for the baggage and pilot door.  These use a cylindrical key which will hold up better over time, however you have to order (Part M930101211W010J) or make a longer cam for the baggage door.For the seals I went with 10 feet of McMaster-Carr 93085K67.

Done pending locks and seal

Steps Install, Fuselage Conduit, Sound Proofing/Insulation & Baggage Area

Steps Install

Section 30

A majority of this was completed by the quickbuilders so it's not really a time sink, really all that's left is pushing in the actual steps and bolting them in place.  However slight problem with my kit as I didn't get the two AN3-20A bolts used to final attachment. They are typically shipped holding a temporary bar in place... however that wasn't the case with mine and holding my temporary bar in place were crate wood screws instead, no big deal Vans just had to send me a few.

During nightly research reading session I learned that there have been cases of these steps becoming loose over time.  A few solutions builders like to do is to install inspection panels made up of the stall horn access plates so you can visually inspect the bolts and tighten if need be.  These panels don't allow you to take the screws out so I don't really see the point.  Also continually tightening the bolt will just space the pipe, so I went with a different solution.

I bought Step Bushing from TCW technologies which more or less fill in the space allowing a tighter more secure fit.  I literally was able to push the bushings down into each step using a hammer, piece of PVC and a string (In case you have to pull it back out).  Then it's a matter of torquing the bolts down to spec and moving on.  If there comes a point where I need to visually inspect this area I can retro fit an access panel, much like I did on the wing.

Fuselage Conduit

As with the wings I struggled a bit on how to route the conduit.  Then I found a Matronics post with some great pictures, even reached out to Carl Froehlich for some clarification.  In the end I did a total of 6 (3 each side) runs using the flex pipe from Vans.  Where I needed to drill 3/4" through the seat panels and ribs I made some doublers.  Probably didn't need them but gives it a cleaner look in the end.

Drilling these were not easy

Sound Proofing/Insulation

Some say you don't need it, some say you do... I decided I do despite flying with a fantastic ANR headset.  The product I went with was 1/2" Self adhesive foam from  Soundproofing.org. I suggest going through them because for whatever reason ACS really ups the pricing going from 1/4" to 1/2".  I ordered 20' worth, and it's too early to tell if that's enough or over kill but so far it looks like I should be able to do the cabin side of the firewall and the walls.  I can't take credit for the install though, that's being done by my wife who has found her niche in aircraft construction.

Another place I've added insulation is under the front floor boards.  Since I wasn't able to remove the floor panels due to the gear weldment I decided to just spray foam instead.  The aviation section of Home Depot has some fire resistant canned stuff that worked well.  Just place some paper or tape or something under the rear holes and get to spraying.  After shooting a can under each side let it cure for a day and cut out any excess that squeezed out.

It's the orange stuff

Baggage Area

Section 33

The baggage area was an on again, off again piece of work that I've been cracking away at for a bit. There's some decisions that you have to make such as conduit, soundproofing, step and other odds and ends posted above prior to riveting down the floor boards.
The plans also separate out QB vs Standard build actions however maybe the guys in the Philippines were working off a different set of plans because they missed a number of items.  Not a huge issue just need to double, triple check what was supposed to have been done was indeed complete. The rest of the actions required isn't anything challenging but does take some time.  There's a lot of drilling, a lot of nutplates, a good bit of riveting and such.

I did borrow a friends pneumatic cherry rivet gun to try on the floors.  Here's a picture of it...

It actually takes a bit to get used to. You need to make sure you have the correct end on it, I had an end that was for more of a LP rivet so when I ran some CS rivets it rounded the top requiring me to drill them out.  After about 10 mins you get the hang of it and you can whip through pulled rivets like nobody's business.  There are still areas though where the cramped spaces require you to use a traditional hand riveter.

Below are some pictures of the progress at random points...

Those bushings are to protect the panels from the seat belt cables

That's the baggage area completed