« Posts tagged exhaust

The Skinner

February 18, 2013 / posted in Firewall Forward, Fuselage / No Comments

3 hours.

And yes, it’s a shout out to Neal Asher, whose writing has gotten me through a tough couple of months. When you’re having horrible-seeming things happen to you, reading about truly horrible things happening to somebody else and the truly horrible people who cause them getting their comeuppance is very therapeutic.

As far as this aircraft project goes, yesterday was not horrible. I actually might have the temerity to call the firewall-forward process almost done. The only two things missing from the equation is a 2″ hose clamp for the cabin heat SCAT tubing (which is actually missing, I can’t find it right now) and the manifold pressure sensor fitting and tubing, both on order from McMaster-Carr. I can look at the engine installation and say with fairly high confidence, yes, this engine will turn the propeller repeatedly. Today I’ll go through my periodic shop purge/clean ritual and see if the clamp turns up.

I also took a long look at all the stuff just behind the firewall and ahead of the subpanel, to make damned sure there was nothing else I needed to put there, because as I’ve mentioned before, once you rivet that top skin on, you can’t get to anything below it without a flashlight, a mirror, and possibly tentacles. Satisfied to the limits of my ability with such things, I began riveting the top deck skin on. This is hard. This is hard because you have to have a rivet gun on one side and a bucking bar on the other, separated by a 3-foot sheet of metal and ‘awkward’ only begins to describe the process. There are two holes in the subpanel support capable of taking my hand holding a bucking bar through them, and it’s a little like the reverse of a monkey trap. There is much maneuvering into position, then there is riveting, whilst holding the bucking bar perpendicular to the rivet without being able to see it. This process enabled me to do the center row of rivets, and the canopy hinge support bracket, but failed on the outboard subpanel support rivets because to get my hand into the right position, I had to bend the skin away from the surface it was being riveted to, causing a gap. I couldn’t get the leverage I needed and the skin ‘pillowed’ on the support rib. Bah. Curses. Foiled. I’ll need to enlist a helper for this step, but as soon as it’s done, I can put the canopy back on and officially list the project as ‘more parts assembled than not.’

More firewall forward progress… And regress.

January 7, 2013 / posted in Firewall Forward / No Comments

5 hours.

The latest load from ACS allowed me to finish a couple of things. I got the oil pressure line/oil line adel clamp securing done, I finished the purge valve bracket assembly, I got the fittings installed on the oil cooler, and I actually got the prop governor installed, and the front center baffle reinstalled. I painted the throttle and mixture brackets and put them back on, and I re-secured the current sensor to the alternator wire. This is where it all went south.

I also finished attaching the fuel hose to the throttle body, and securing it to the intake pipes, but this is where it all went horribly wrong. I had purchased a steel 1/4″NPT-AN6 elbow, but I was using one of the blue aluminum ones to get my fit and mount done. The Floscan is on the firewall, and the elbow points toward the intake pipes on the left hand side of the engine. I had the fuel line connected to this. Somehow, in backing out the AN6-1/4″ NPT elbow on the output side of the Floscan fuel flow sensor, I managed to cross-thread the fitting as I was taking it off. Taking it OFF, not putting it on. So what it did was essentially pull on one side of the threads but not the other, kind of just bending the whole thing. Long story short, I completely destroyed the threads on the Floscan and it will have to be replaced. That was a very expensive ($210 from MGL Avionics) lesson in not connecting loads to dry-fitted NPT fittings loose enough to jam up. I did finally manage to extract the threads left in the Floscan housing and re-tap them, but I don’t trust the connection anymore, especially not with high-pressure fuel running through it. Now would be the time to switch to the Red Cube, except that now I’m reading about failures of these units, plus my firewall mount is drilled specifically for a Floscan. The time for experimentation is pretty much over.

I also got a tube of red RTV for sealing the baffles and putting some blobs wherever things might rub that I didn’t get with Adel clamps.

I still have to track down a hose from PHT (throttle body to fuel spider), but that’ll have to wait until tomorrow. My intercylinder baffles are on their way, and once those get installed I can permanently reattach all the baffles. I can also rivet the firewall to belly skin, because I’m giving up on making an exhaust fairing for now.

More fiberglass fun – Cowl and baffles.

September 4, 2012 / posted in Firewall Forward / No Comments

4 hours.

Not a complete balls-up, no, but close enough. Yesterday I finished the lower cowl inlet baffles. Almost. I still need to cut away some extra airseal that blocks a portion of the snorkel intake, but other than that, I’m done with airseal. I hope. That’s the good news.

The not so good news is that I decided to move on to filling the pinholes in the pepto-pink lower cowl. Of course I cocked it up, because I failed to remember one simple thing: The resin mix is supposed to be applied to the surface with a squeegee, not just slathered on with a brush. I should also have cleaned the surface with acetone, then soap and water before applying. So now I get to sand off a bunch of resin and redo it. Fortunately, I didn’t do the whole thing, just the front third, but it’s still a pain and a lesson in attending to detail.

Since that was going to have to wait for another solid block of time, I decided to finish the heat muff install. When I received the heat muff, one of the lock nuts on the through-rods didn’t have threads in it. I got some replacements from the manufacturer, and that is now installed. I also cut and attached the SCAT tubing to the muff, the heater box, and the baffle vent. OK, that last part still needs to have the hose clamp tightened, but it’s pretty much done.

Snorkel Again, and Exhaust.

April 8, 2012 / posted in Firewall Forward / No Comments

5 hours.

Today I did some more work on the snorkel, this time trying to shape the throttle body side to allow for smoother airflow, fill in some voids in the opening, and generally beef the thing up where the interface is.


This is looking into the relief hole I made for the alternator. You can see that the demoisturizer container serves as a perfect plug in place of the throttle body and the tape wrapped around it is exactly where the lip on the TB would be. The dark bit on the right inside the hole there is a void that didn’t get filled on the last glassing pass. I roughed up everything, cleaned it out, and went to town.


This is looking in from the top, where the air filter will go. It looks pretty anatomical, I know. The thing I have to fix now is where the opening bulges up, which will create a turbulent airflow.


Weapons of the trade. That’s the Builder Shield plastic on the left, and West System 206/105 epoxy resin on the right with the pumps sticking out. Living 3 miles from Marina Del Rey, I’m fortunate to have a West Marine store where I can buy this stuff. I wanted to get the 206 hardener, because I needed more pot life from the epoxy. I can wait the 10-15 hours for it to cure.

The photos stop for a bit, because of the whole resin/iPhone thing again. The next step was mixing up a bunch of micro to fill in some voids and take a crack at shaping a more gradual transition inside the snorkel where that burble was going to be. The first thing to figure out was how to fill in the voids around the actual opening itself. What I wound up doing was fairly genius (assuming it comes apart properly tomorrow). I wet down a strip of glass cloth, put it on the inside of the opening ring, then jammed the plug through it. It should form a perfect shape around the plug, and I can easily cut/sand off the excess on either side.


Here, it’s about done. There’s micro in there, and a couple of layups of glass around the burble and the rest of the edges go hold everything down. I also put a couple more layups on the outside to thicken up the interface ring.

With that curing, I went hunter-killer on some of the smaller items that I’ve been blowing off. First thing was reclocking the prop governor cable bracket.


This bracket also goes on the IO-540 in the RV-10, but the -7’s cowl doesn’t have enough clearance to let that happen. I’ve seen one or two examples of putting a bump in the cowl to allow the bracket to clear, but since I want to do as little fiberglass as possible, I decided to reclock the bracket. That just involves drilling two offset holes. The bracket will stay on just fine with two screws. I didn’t need to do much, that’s maybe a quarter-inch of distance between those hole, but I managed to bring the end of the arm down enough to where there won’t be any interference issues with either the cowl or the #2 injector line.

Since it’s time to think about things like control cable and wire routing, I decided I should probably put the exhaust system back on. The more things that are actually on the airplane, the fewer guesses I’ll have to take when deciding where to run things. Forward of the firewall, the name of the game is keeping things from picking up too much heat, and the primary source of that is the exhaust. The recommended distance between the exhaust and anything else is half an inch. Anything comes closer than that, and it needs to be shielded.


What you see here is the 4-pipe Vetterman exhaust I had to purchase to replace the crossover 4-into-2 type I had before. With the Crossover exhaust, there’s absolutely no way to get control cables to the throttle body without a horribly complex series of bellcranks and other things I really don’t want to mess with. The 4-pipe setup has a nice wide space up the middle where I can route the mixture and throttle cables without getting them too close to the pipes.


Since the right aft baffle is already on the engine, and finished enough to matter, I thought it might be a good idea to get the two-pipe cabin heat muff set up, along with the suspension by which the aft sections of the pipes hang. I’ll admit, I can’t find the instructions or drawings right now, but it really only makes sense to put it together one way. This is all about making sure I have all the parts, which I do, except one of the nuts is defective. There are no threads in it. I don’t even know what that type of fastener is called, to be honest, so I’m going to tap it for whatever threads the connecting rods between the brackets are. Like the crossover version, the pipes hang from stainless steel tubes connected by sections of rubber oil hose, so that’s no mystery. But with this and the baffle in place, I’ll be able to hook up the cabin heat system.

Wandering aimlessly.

February 14, 2011 / posted in Electrical, Firewall Forward / No Comments

4 hours.

I got a call from Don Rivera at Airflow Performance regarding the quandaries of my servo installation. He said I was basically on the right track, but that yes, i’d have to make my own brackets for the throttle and mix cables. Also, there’s no reversing the butterfly. I found about $200 worth of hoses that can go back to Van’s, and I got the temperature probes installed and the extensions run back to the RDAC. I almost got the breather tube done, but I really need to get off the FWF install and go back to wiring and avionics. Basically, I puttered around, unfocused, looking for an easy way into the next step. There isn’t one. I don’t have the cables, hoses, or fittings I need to do more FWF, so screw it, I’m going back to electrical.

This is harder than you might think. Every time I walk past the engine, I find something to distract me. All these little distractions start out as “I wonder if THIS will work.” As a result, I got nothing significant done, other than the installation of a couple of probes and senders. Not that this is a bad thing, but if I had focused on avionics and panel, I could have gotten a lot more done, since I have all the stuff required to get that done.

I’m also looking at the baffles. I suspect I might have some problems where the prop governor sits, and that is going to suck.

Powerplant installed. Next: Kessel Run.

February 7, 2011 / posted in Firewall Forward / 2 Comments

12 hours.

This is a tale of the 36 hours beginning Thursday the 3rd. It started with a text from Shelley, who said my EFIS had arrived from MGL Avionics. The unboxing revealed this:


This is the MGL Stratomaster Odyssey EFIS. There are many like it, but this one is mine. I hooked it up with the backup battery, plugged in the AHRS and compass and flew over SMO. My house is about a mile away from SMO, so I set the barometer high enough to see over the hills and rolled the sensors around. The EFIS responded brilliantly. Setup should be a snap. After that, I put it away in its box and went back to work. While I was there, I got a call from Tim at Tim’s Aircraft Engines, who informed me that my engine was done. Friday morning I went to pick it up. After some interesting work with the hoist, the guys managed to get it into the back of the truck and get it strapped down and I was able to bring it home.

So, to recap. We started with this eBay special:

Gutted it for the conversion, but found spalling on the lifters. Boo.

This stage is pre-assembly at Tim’s Aircraft Engines:

And here it is coming out the back of the truck at home on Friday:

It’s so. Freaking. Beautiful.

And here it is, ready to go.

Dave had promised me he’s stop by and lend a hand this weekend. He did, bright and early Saturday morning. He bucked some rivets on the antenna and fuel fitting doublers that would have been impossible for me to do with anything but pop rivets. After that, we were originally going to lay out and cut the panel, but I said why not hang the engine instead? I’ve got all the truly annoying firewall stuff done, Dave’s here, and I can cut the panel on my own.

So I set up the engine hoist (this thing has been useful more times than I can count now).

Getting ready to lift it into place. Some guys have done this on their own, but I just don’t see how.

Shelley stopped by the shop to see what all the cursing was about, and fortunately she had her camera.

I asked her to document the process. It wasn’t that bad, really.

Watch your fingers, guys.

The last bolt is a complete bastard. If it isn’t, run out and buy a lottery ticket right then and there.

No, I’m not about to beat the engine into submission with the Red Stick of Death. I’m holding the engine hoist bar above my head in celebration. This is the Tin Man’s heart transplant right here, a significant milestone on the way to being finished, or at least flying.

One thing we had to do was take the fuel servo off and rotate it 90 degrees so the inlet was on the side. This is per the AFP manual. This has the effect of putting the control arms for mixture and throttle on the bottom, where there’s just barely enough room to get control cables to them. Unfortunately, none of the hoses supplied in the Van’s FWF kit work for this configuration, so I’ll have to send them back and get some custom ones made at Earl’s.

(Update: turns out the hoses are probably OK. I forgot that between the firewall and the fuel servo is a rather large and unmistakeable engine-driven fuel pump that has a hose going both into, and out of it. This will more than make up for the discrepancy in length.)

Charged with the rush of success, that being measured by the fact that the engine didn’t fall off and crush one of us to death or disability, we tackled the exhaust. After losing an hour to the fact that we both caught a case of the stupids when it came to the heat muff, we got it all hooked up. trimming the stainless steel support tubes dulled up my bandsaw blade, but it worked long enough to get the job done. Fortunately I had a spare.

Today was rather anticlimactic. All I did was fabricate the mount for the EFIS backup battery and ponder bracketry for a while. Of course, it was Super Bowl Sunday, so we all went over to Dave and Peggy’s to watch the game.

Dave, thanks a gazillion for all your help. You get the first passenger flight, if you want it. And if Shelley doesn’t.