Misc - Firewall, Brakes, Static

The fuel tank attach bracket doesn't actually bolt to the fuel tank bracket like you'd think it would.  The hole in the bracket on the fuselage actually gets opened up so that the bolt can easily rip out in a crash.  This allows the wings to depart the fuselage if they hit something - this helps dissipate energy, as well as allows the fuel tanks to separate from the fuselage.  We had just temporarily bolted the brackets on when fitting the wings, so I removed them and cut out the slot, then bolted them back in place.

It's a little hard to see in the picture, but I pop riveted the insulation to the firewall using stainless steel rivets.  I spread sealant around the various penetrations as well (not shown in the picture).  I'll give the sealant a day to cure before I start taping over the joints with aluminum tape.  I only cut myself a half dozen times while putting rivets in.  You'd think I'd learn and wear gloves.

I'm a glutton for punishment, so I climbed up into the fuselage to hook up the static line in the tailcone.  I bolted the push fitting to the bracket I had riveted to the longeron.  This will support the static line as it runs to the center and up to the ADAHRS unit.

A long time ago I purchased steel braided brake hoses from Aircraft Specialty.  This is to replace the Van's approach, which is to use aluminum tubing down the leg and to the brake.  That approach works, but it's known for being prone to leaks over time after you've taken the brakes on and off a few times.  The braided lines are slightly longer than the gear leg to allow them to curl around a bit at the brake and allow for some flexing.  Since I'm pretty much past the point of having instructions from Van's, I looked up a few other builders to see how they attached the hose to the legs.  The consensus is that hose clamps don't really work because of the tapered leg.  As odd as it may seem, it sounds like most of the 11,000 RVs out there use electrical tape as the mounting method.  I cut some vinyl tubing into 2 inch pieces and slipped that over the brake line to add a little extra protection.  I don't love electrical tape, so instead I decided to use the self-fusing silicone tape, which sticks to itself really well and doesn't leave the nasty mess that electrical tape does after it's seen high temperatures.  I attached the lines at three places, then to give just a little extra layer of toughness around the silicone tape, I put a layer of Gorilla Tape on it as well.  All of this will set underneath the gear leg fairing.  I think it should work just fine, but is easy enough to redo 10 years down the road if need be.

To my surprise, I already received the oil filter bracket spacer from Continental!  I told them I didn't need it right away, but they overnighted it to me anyway.  This will definitely move the filter back far enough to make it easily accessed.  I'll attach this at some point before I run the engine, but I'm in no rush.

Engine & Gear Install

Another big milestone!  Time to put the plane on its gear and hang the engine!

I trimmed a few areas of the firewall insulation and foil to ensure that nothing would be pinched underneath the engine mount points. Back when I had test fit the mount and drilled all of the firewall holes, I noticed that the lower outer mounting points were not in the same plane as the rest of them.  That's apparently not all that uncommon.  To take up that gap, we placed a 1/16" thick washer under each lower outer mount point.  With those in place, we put the bolts in and torqued everything down.

I don't have a picture of it specifically, but before we put the mount on, we installed a number of the firewall items, as well as cut the fiberfrax and foil for the recess.

The battery, solenoids, shunt, etc are mounted on top of the insulation, so they do their part in holding it all in place.  The fiberfrax compresses pretty well, so even though it starts out soft, you can still crank down the nuts and screws fairly solidly.  I still need to buy a few longer screws for the fuse holders, so those aren't in place yet.

After the mount was on, we chained it to the engine hoist and lifted the plane off of the rolling cart that has supported it up to this point.  All three gear went on relatively easily.  I put a light coat of grease inside the main gear tower, just as a protection against corrosion.  I've gotten so used to seeing the plane sitting close to the ground that it really seems tall now that it has legs!

Next up, the engine!  It was a bit of a struggle just to get the engine and hoist close enough together.  We tipped the crate up and slide the hoist underneath, which got us close enough that we could then lift the engine and swing it all underneath the lift.  We eyeballed the chains and got it set to what we thought would be a level position.  If we had it to do over again, I would have actually tilted it back a tiny bit to help with alignment, but it worked okay as-is.

The install wasn't easy, but it also wasn't hard.  It's just very sensitive to the slightest off angle.  We started by putting in the lower bolts and tightening them up completely.  Then we let the engine sag under it's own weight (plus the weight of both of us pulling it down), which opened up the top mounting points enough to slip in the top donuts.  The top two bolts took a bit of wiggling to get in place.  With the gear and engine on, she's beautiful!

I discovered one gotcha with the engine install - the Titan comes with a 90 degree oil filter attachment, which allows the filter to more easily be accessed.  Unfortunately, the attachment put the filter right under one of the mount arms.  It was so tight that before I noticed it, we had crushed a small corner of the filter.  I shot off a couple of emails to other builders who I know have Titans, and they all said it worked fine for them.  After one sent me a picture, it was obvious that there is a big spacer that can be inserted on the attachment that pushes the filter a few inches aft.  I sent an email to Continental asking about it, and they responded with an apology, saying they must have forgotten to install the spacer.  I'm guessing they don't always put it on the engines, and they may just not have tracked the fact that this engine was intended for an RV9A, which obviously needs it.  They were great about it though, and said they'd ship me the part right away.

Mains - Brakes

The fairing brackets on the main wheels bolt to the inside of the collar that the brake bracket also bolts to.  There is also a small fairing bracket that screws into the axle nut on the outside, but I won't put that in place until it's time to install the fairings.  The brakes attachment is a little strange - the main body doesn't actually mount solidly to anything.  The body has two pins that slide into the attach bracket and allow the body to move in and out.  With the body in place, I slid the outside shoe in and bolted it in place.  The sliding pins and the brake shoes are all that hold the whole assembly on the wheel.

Firewall Holes & Nose Gear

One step closer to getting the firewall penetrations finished up!  I'm now at the point where there is no guidance by Van's regarding locations, so I've been sitting and staring and mulling over what will need to go through the firewall.

The manifold pressure sensor will connect to cylinder 3, so it'll go through the firewall on the upper right side.  Van's provides the kit for plumbing, but not the sensor itself (which I got from AFS along with all of my other engine sensors).  I held the brake fluid reservoir up to see where it would go, then just eyeballed where the fitting could go for the manifold pressure plumbing. I put a little fire silicone sealant under the fitting, even thought once the insulation and foil is on, I'll also surround the cutout with sealant.

After that was set in stone, I moved on to the right side pass through for wiring.  There are a lot of ways to accomplish this, but the most common is to use a flanged tube that extends through the firewall and gets wrapped in fire sleeve.  Then, another piece of fire sleeve is inserted into the tube, mostly to aid in sealing around the wires.  Once the wires are in place, fire sealant is pumped into the area to provide a gas tight seal.  The problem - this little kit of a flange and a small section of fire sleeve is $90! And I need two.  I know aviation is expensive, but that seems pretty ludicrous. 

Those crazy expensive tubes look awfully similar to a good ol' closet rod hanger.  Funny enough, when I searched on that on the forums, I found that a lot of people go the route of the rod hanger.  I found two stainless steel hangers on Amazon for $10.  Combine that with $20 of fire sleeve and a few hose clamps and I've got pretty much the exact same setup as the real deal for about $130 less.

I drilled a pilot hole in the firewall, then upsized it until my knock out punch would fit.  I bought a cheap punch set from Harbor freight.  It's made for conduit sizing, so it's a tiny bit off from what I needed for the tube.  I used a grinding stone in my die grinder to chew away the last 1/32" I needed to get the tube through.  Then I drilled matching bolt holes in the firewall.  I made a doubler to go on the forward side of the firewall and riveted it on.  I forgot to put sealant under the doubler when I riveted it down, so I slathered it on liberally once I was done.  Like with anything else that is permanently fixed to the firewall, it'll get another layer of sealant after the insulation and foil is cut around it.

The manifold pressure sensor AFS sent is nothing special.  It looks like it's probably an automotive setup.  I decided to mount it vertical instead of horizontal to get the intake tube higher than the level of the firewall fitting.  The instructions say to try to keep it so water can't run into the sensor.

Something I just randomly found out while I was digging through various websites and manuals is that the Pmags also use manifold pressure to help with their timing.  I will have to put a T in the manifold tubing by the sensor and run it back out the wire penetration to connect to the Pmags (it'll need a second T in the engine compartment since it'll have to split and go to both Pmags).

I repeated the whole process for the left side.  Of course it went twice as fast.

There are a couple of other mounts I need to sort out tomorrow - one mount for the AMP shunt and one for an ANL fuse.  The ANL fuse was a late addition that I decided on today.  Even though aviation alternators have over voltage protection, there's still some paths where a short or other electrical failure can fry downstream systems.  The ANL fuse is a 60 amp fuse that will be in between the alternator and everything else.  If the alternator truly implodes, I'll have one extra layer of protection.  Putting a $20 fuse in to protect many, many thousands of dollars of computers just seems like a no brainer.  I guess it's not something most people do (probably simply because it's not included in Dynon's standard engine wiring kit), but it was recommended in Bob Nuckoll's book "The Aeroelectric Connection."  That's basically the electrical bible for experimental aviation.  Apparently boats also use ANL fuses a lot, so I was able to find the exact fuse and mount sold by aviation suppliers on Amazon (for a fraction of the price of course).  

Moving on from the firewall for the day...

The parts I painted yesterday were cured enough to handle, so I went back to working on the wheels.  I riveted nutplates onto the nose wheel fairing brackets.  These brackets will be what the fairings screw onto.  The brackets are attached underneath the axle bolt washer and nut (there are two smaller washers that provide thickness spacers for the brackets), and the front is screwed to the fork using big allen bolts and lock nuts.

The gear leg is drilled through at the top to attach a collar with a bolt.  This collar acts as the rotation limiter by bumping up against allen bolts that are screwed into the top of the fork. Simple and effective.

I pumped the fork full of grease and then worked on setting the break out force of the wheel.  There are two huge "spring" washers on the bottom of the gear leg, then a nut.  I slowly tightened up the nut and moved the wheel back and forth until the breakout force was 22 lbs.

Wheels - Mains

Not much to show today.  My FWF parts were supposed to be delivered today, but I missed the UPS truck, so now I have to wait until Monday.  There are just a handful of things left to do on the gear and wheels before they are ready to be assembled.  Once I get the new primer this coming week, I'll spray the parts and do final assembly.

It's hard to show in a picture until the parts get bolted together, but the inside bracket that the main gear wheel fairing attaches to needs spacers to hold it away from the brake disc.  It's kind of pathetic how long it takes to make simple spacers, especially when they all need to be the exact same length.

The last thing the main wheels need is for the axle to be drilled to accept a cotter pin for the axle nut.  The nut is already drilled with holes in each face, but the axle does not have matching holes.  I put the inside and outside axle spacers on and tightened down the nut (just hand tight - it is only there to take side to side movement away and isn't supposed to get torqued down).  I spot drilled one hole then took the nut off and ground away the threads with a small round ball bit in the Dremel.  Hitting the threads with the Dremel made it much easier to center the drill vs trying to get it started on threads.  Once I had the first hole drilled, I put the nut back on and pinned it in place with a drill bit in the first hole.  Then I did the same process to get the opposing hole drilled.

Brakes & Wheels

I already received my wheels back from having the bearing modification done.  This gave me a new set of things I could accomplish while I'm waiting on my firewall parts.  You can see the new sealed bearings they pressed into the wheel (one in each wheel half) in place of the tapered roller bearings that come with the wheels.  Having these new bearings will mean I don't have to repack bearings every year, and they should also help to keep the common issue of gear shimmy from happening (due to very finnicky axle nut torque, as well as worn bearings over time).  Even though the modification was initially developed for the nose wheel, it's now something the company offers for all wheels.  I went ahead and had them do the main gear wheels as well.

The wheels come split in half.  I used talc on the tubes and inside of the tires (allows the rubber to slide and minimize the chance of the tube getting wrinkled and caught in between the wheel halves or the tire bead).  The valve stem gets placed near a painted dot on the tire which indicates the lightest spot of the tire.  I inflated the tube just enough to have shape, then slide it into the tire, put the wheel halves in place, and torqued down the bolts.  On the main gear wheels, the bolts also hold on the brake discs.

The nose wheel is a little different than the mains.  It gets an axle insert (the blue piece) that slips between the fork, whereas for the main wheels the axle is part of the gear itself.

The other side of the nose wheel has a spacer and a nut.  All of this will slip in between the forks of the gear leg. 

The fork is a very solid chunk of material, but it was in pretty sorry shape.  I spent quite a bit of time trying to polish out all of the dings and cut marks, which I assume were just due to mishandling during manufacturing.  It'll all be hidden under a wheel pant, but I didn't want any possible stress risers in it that could potentially lead to cracking.  I want to give the fork a protective coat of primer since it'll be exposed to water, and I want to use an epoxy primer, which will be tougher than the typical primer I've used on the rest of the plane.  Even though I have a little bit of it left, I'm not really all that sold on the water borne epoxy primer I have used from Stewart Systems.  It's just not nearly as tough as an epoxy primer should be.  I ordered a quart of Kirker Enduroprime - it's an automotive 2 part epoxy primer that I've heard good things about.  Supposedly very tough, but not quite as expensive as the typical aviation epoxy primer.  So for now I'll move on from the nose wheel setup.

The main gear axle gets a brake flange bolted to it.  This provides an attach point for the brakes themselves.  The axle already has a 5/16 hole drilled through it, and the part with the flange has one hole that is the right size and one hole that is undersized.  Why they did that, I have no idea.  I needed to open up the smaller hole to 5/16, but I didn't want to do that with the part on the axle.  I probably could have put the flange on the axle and just used the hole in the axle as a guide, but I was afraid of the possibility of accidentally enlarging the axle hole.  I did it on the drill press instead.  That worked fine, although the hole (in both left and right gear pieces) was a hair off and made getting the bolt through a bit of a chore.

I still haven't quite wrapped my head around how the brakes attach.  The instructions are virtually non-existent, and the single drawing doesn't exactly scream clarity.

Piece by piece I'll figure it out though.  Each brake is mated to a piece of aluminum that is used as a mounting point for the wheel fairings.  These pieces still haven't been redesigned since Van's switched brands of brakes (20 years ago...), so they don't actually fit as-is.  I had to cut a half circle out of each plate so that it would fit around the upper bolt/pin on the brake mounting plate.

I'll probably keep working on the brakes tomorrow.  I'll get as much of it done as I can so that once I get the new primer I can just spray the parts and assemble right away.  I waffled on whether I should wait to do the brakes and wheels until the gear was installed on the fuselage.  I decided it's probably easier to put it all together first so that I only have to lift the plane once to install the gear vs lift it to install the gear, place the center fuselage back on blocks to keep the axles off the ground, then install the wheels and lift the plane again to get it off the blocks.

Wheels & Canopy Prep

The proseal is almost dry enough to start messing with the canopy, but I want to give it another day to set up so it doesn't attract dust and shavings from the process of fitting the canopy.  I've been told that it's best not to let the tire tubes stay folded up for too long, so I decided to assemble the main wheels for a change of pace.  The wheels are made up of two halves with the brake rotor bolted to one side.  The bolts holding the halves together are set super close to the wall of the rotor, and I couldn't get a socket or wrench on them.  I ended up grinding down the wall of an old socket until it was super thin.  The bolts are only torqued to 100 in/lbs, so the socket doesn't have to be all that beefy to do its job.

I covered the inside of the tire with talc to help the tube slip in and keep it from catching and creasing during the assembly process.  Then I put one half of the wheel in place (it has a notch cut out for the valve stem, and the valve stem has a nut on it to center it in the notch).

The other wheel half went on next with the brake rotor set on/in it.  The bolts go through the rotor and both wheel halves and were torqued to 100 in/lbs.  I inflated and deflated the tire a number of times to help the tube settle into place.  The first tire took a while to figure out since there are zero instructions about how to do it other than a short blurb that came from the manufacturer (Matco).  The second tire was done in a matter of minutes. I won't add the brakes or anything until the plane is up on the gear.

I'm slowly checking off all of the random things I can do while I'm psyching myself up for the canopy fitting!  There is a never ending list of course, but I'm ready to get going with the canopy.  Once done with that, then the departure from the Van's instructions begins (electrical and firewall forward).  There's just not much guidance from Van's once you get beyond the basic structure.  I'm definitely thankful for all of the information online these days!

I set the canopy frame back on the plane and pinned the hinges.  In order to make sure everything is in its final position, I had to put the front fuselage skin back on as well.  This skin is still an excruciatingly tight fit though, so I decided to leave the outside most holes unclecoed and just strap it down for now.  If I cleco those longeron holes too many more times, they will start to elongate from having to pull them into place.

The canopy doesn't come with any layout on it that would aid cutting it symmetrically at the front (it starts with a somewhat straight center line then curves around to the canopy rails).  I'm not sure if it'll end up helping or not,  but I printed out some grid paper and taped it to the glare shield.  The lines don't come together perfectly, especially at the aft edge since the glare shield isn't flat, but I think it'll still help me get in the ballpark of symmetry from side to side.

And here it is!  There is a lot of material to trim from the front and back.  The first step will be to trim all of the excess material off that is there to help in the forming process.  Once the basic shape is set, then it's iterative trimming of the front to get that shape correct, following by splitting the front canopy from the rear window material.  Only after you've done that will the front canopy set down on the roll bar enough to trim it to final size.