Joshua's RV-9A Project

Started out by giving more attention to the HS/VS tips (the elevator/rudder tips don’t require so much work, and I’m glad for it).  Sanded the filler layer of micro I added yesterday, and got things looking relatively decent.  Spent some time reading on what the process is from here; it looks like there should be an epoxy sealcoat or three over the microed area, then a primer, and possibly another primer after that.  I’m reading much of what DanH has written over at VAF, and have found the specs for the PPG coatings used by many of the folks; have to see if there is a local supplier, or if it’ll be a mail-order operation.  DPLF is the basic primer, and K36 is the high-build primer/surfacer.  The finishing steps, as I understand them, are to brush or roll 3 layers of straight epoxy, then sand, shoot DPLF, sand/fill if necessary, then a light coat of DPLF and a coat or two of K36.  I don’t know if the K36 step is needed at this point, or if that’s something that’ll happen at paint prep time.  After sanding them up, I added a fillet of flox to the inside of each tip, to strengthen up the joint at the back.  Hopefully these will be done soon…

Next I tackled the pre-installation for the SD-8 backup alternator/dynamo.  I’ve installed the relay and capacitor, but haven’t bought the regulator or dynamo to save the $500 for the moment.  This is purely a backup device, so I don’t need it to get flying, but want to add it eventually.  I drew up a full-size paper mockup of the regulator so I could locate nutplates to secure it, and installed those.  Then, I installed all the wiring, and ran the lines which run to the regulator to a CPC connector mounted below where the regulator will go.  When I get the regulator, I’ll put a mating CPC on it, and it’ll be a simple matter of bolt in and plug in.  Also ran a loop of wire FWF and secured the excess length to the wire bundle along the upper engine mount tube, where it’ll stay until the installation of the dynamo.

Started on the installation of exhaust mounts.  Tightening down the bolts on the ball joints to the specified 2-threads caused them to become rather tight, so I may need one length longer bolts there — not sure how tight or loose it’s supposed to be, but the install guide does say that it’s important they be able to flex, and recommends lubricating them regularly.  Got the right side hangers fit, and the left side marked and cut, before quitting time.

And, stuck the biennial registration sticker on the ELT.

Sanded down the filler that was added to the empennage tips, checked fit, and put on another thin layer of micro to fill the voids opened up by the sanding.

Still working on getting the wings to the point of being ready to move to the airport.  Installed all the nutplates (52) for the wing root fairings, after making a poor man’s nutplate jig (insert a screw partway into the nutplate, then cut the head off) for both the two-leg and one-leg nutplates.  Had to dig a bit to come up with the one-leg dimpled nutplates for the 4 locations that require them.  Nothing difficult, just lots of repetitive little stuff.  There is one nutplate hole on each lower leading edge that’s impossible to dimple with the dimple dies because the tank support bracket is right behind it — I found that it worked to install the nutplate, then use a screw with a tinnerman washer to form the dimple.

Also deburred, dimpled, and primed the wing inspection plates, and poked at the empennage fairing a bit more, to think about the next steps in fitting it.

Trimmed and sanded the edges of the glass layups on the HS/VS tips, then mixed up a batch of micro and slathered it on the inside.  Once it’s cured, I’ll remove the foam rib and finish the inside layups.

Laid up another ply of glass on the back of the empennage tips.  Hopefully that will stiffen it up enough to remove the foam rib and add glass to the inside.  Left to sit and cure overnight…this glasswork looks like it’ll take awhile just because of all the waiting around.

Riveted in the rest of the wing inspection panel nutplates.  All that’s left on the wings for now is to drill, countersink, deburr, and rivet in 52 more nutplates for the root fairings.  Oy.  I’ve dealt well with all the nutplates on the project so far, but this job makes me wish I’d bought a nutplate jig.

Allison tried to escape the heat in the shop tonight (though we finally gave in and got the central air fixed in the house…)  Drilled, deburred and dimpled the nutplate holes for the inspection plates in both wings, and riveted the nutplates on the left wing.

Also put the top & bottom cowls together to see if they still fit together with the inlet ramps glassed in, which they did, rather nicely in fact.

A bundle more of fiberglass work today, including my first real dive into mixing up epoxy with additives, and using it for more than sticking a ziptie base to something.  By the end of the day, I had used four small batches for various things, and had the discarded cups to prove it (I kept the excess in the cups and set them aside so I’ll be able to verify that the batch cured correctly, without any mixing errors/etc, and to observe how, and how quickly, the different mixtures set up):

First on the list was to take the necessary steps toward finishing up the empennage tips.  I used a 1/2″ wide steel rule as a spacer to mark a line on the HS/VS tips, that distance from the edge of the counterbalances.  Then, I drew a parallel line 1/4″ back, and cut/filed/sanded to that line, for an even 1/4″ gap.  I suppose this gap could be tighter, but a wider gap leaves less chance of fouling a control surface should something go awry or debris enter in…and, it could always be tightened back up with, you guessed it, more fiberglass work later.

With the gap and shape established, I re-fit the tips to the stabilizers, and formed ribs out of some styrofoam saved from the fuselage shipment; these ribs were inserted into the tips and will serve to hold the shape of the tip during the next steps.  I mixed up epoxy with some flox to a peanut-butter thickness, and formed a small fillet to the rib, to hold it in place.  Herein is the downside to fiberglassing (besides the mess): once it’s in place, it takes several hours to cure to a point where it’s workable.  So, on to other things while it does that.

Meanwhile, I wanted to get the “elephant ear” cooling ramps on the upper cowling, so I can continue trimming of the baffles.  I found a position where they fit well with the contour of the cowl, and drilled two #40 holes for keeper clecoes in the inlet flange, to hold the forward edge of the ramps while the epoxy set.  Mixed up another round of the flox paste, and stuck them on (after sanding to roughen them up, air-blowing the dust off, and a solvent wipe).  Again, sit to cure…on to other things.  Later, once it had set up a bit, I came back, pulled the clecoes, and slathered on an epoxy-micro-cabosil mix at each end of the ramps, to start in creating a smooth transition surface.  It’s trowelled on for now, then the micro mix (which supposedly sands really easy) will be sanded down to smooth it out.  It’ll probably require a second application, too.  But for now, good enough.  Left to cure overnight.

Back to the HS/VS tips; by now the flox fillet cured up well enough that they could be removed from the empennage and they retained their shape.  I cut some pieces of bid cloth and wet them out with straight epoxy in a plastic sandwich, and applied them to the aft side of the tips, covering the foam rib.   I set those aside to cure overnight; the idea is to remove the foam rib, then lay up additional plies of glass on the inside for stiffness.  I may need another ply of glass on the outside before the rib can be removed, I’m not sure — we’ll see how stiff it is tomorrow.  Once the inside plies of glass are added, the remaining void on the back will be filled with micro, and the whole operation sanded down to make a nice smooth tip closure, then primed.

In between waiting for epoxy to cure, I also: cut the slots in the fuselage side tank support brackets, primed them, and bolted them to the fuselage.  Drilled a drain hole in the rudder bottom.  Deburred the wingroot holes for the gap fairing screws.  Drilled and hole-deburred the wing inspection plates. Finished bending the ends on a cotter pin on the engine mount that I’d missed doing that for earlier.  Found the scribe line on the empennage fairing and rough trimmed to it — made the fairing fit much better, it actually looks usable now.  Drilled holes in the corners of the dataplate.

There’s a bunch of nutplates that need to go on the wings (root fairings and inspection plates), then they’re essentially ready to move to the airport — I could also do the tip light wiring before the move, too, but that’s not a big job (cut to length, add connectors, add local ground wire).

ELT batteries came in the mail this morning, so the first item on the list was installing them.  The lithium batteries are good for 10 years, according to the ELT manual, but the expiration date on the batteries is March 2020, so I’ll enter that as the replacement date.  With the batteries in and everything back together, I armed the ELT and pushed the button to initiate the self-test.  One beep came from the audio alert, which is supposed to indicate that the system has passed all its checks and is good to go.  Disarmed the unit.  Also, reached up into the tail and tightened down the nut on the ELT antenna.

Spent the rest of the day working on the empennage.  Lots of fitting, trimming, filing, and sanding of fiberglass tips.  The vibrating saw I bought for the canopy work also works very nicely on fiberglass, so I’m using that to do the rough trims, then following up with a flat file, a triangular file, a half-round file, and a 2′ 1×3 with sandpaper glued to it.  (Drywall corner bead adhesive works really well to stick sandpaper to a board.)  And, the heat gun to warm up a couple recalcitrant parts so they could be shaped.  Finished basic fitting of all the empennage tips, though there’s still plenty to do.  The VS tip needs to have some height added to it to match the rudder, and the left elevator tip has a dip molded into it that will probably need filler.  Plus, there’s the closeouts of the VS and HS tips with foam/fiberglass/micro/shaping them to match the control surfaces with acceptable gaps.

The rudder bottom was the most time-consuming, since it needed lots of trimming to fit around the rudder horn.  I initially trimmed to the scribe lines, and they were close, but not quite.  I have a bit much of a gap under one side rudder horn (oh well), and the other side needed to be sanded down at a taper quite a ways more before the centerline of the tip was in line with the trailing edge.  Once it was fit, I proceeded to fit the aft nav/strobe, using rivnuts to mount it.  Wired it up, adding the local ground called out in the new version of the recommended wiring diagram, and flipped the switch.  Worked well, though the nav light draws so little current that the VP-X’s no-current fault indicator kept tripping it offline, so I disabled that for the nav light circuit.  The strobe draws enough current that it keeps the strobe circuit from faulting; once the other 2 nav lights are connected, I can try re-enabling it on that circuit.

From the “I don’t really feel like going out to the shop but I need to do something to keep moving” file…

Removed the -14 adel clamps from the main vertical wiring trunk, and installed -15 clamps, which are large enough to contain the few wires that wouldn’t fit in the smaller ones that had been originally installed.

Terminated the boost pump power & ground into a 2-pin molex connector to mate with the one I had previously installed on the pump leads.  Test fit and tested that the pump powered up.

Wiped off the rest of the fiberglass tips for the empennage, and traced the initial trim lines with a black sharpie.

Installed the RJ-11 connectors on the ELT remote cable, and plugged it in on both ends.  The batteries I ordered shipped today, so when those arrive, a test will be possible to verify that it’s working correctly, then the ELT can be deemed fully installed.

Made up a couple 2″ test links for the rudder pedal-cable connection out of scrap alum, to test that length before committing to cutting the steel pieces.  Seems to be alright, one thing I noticed is that at full travel, the swaged end of the cable hits the first snap bushing behind the pedals.  Not sure what that’s about, or if it’s normal, but the thing setting that location is the length of cable from the rudder horn.

Having picked up some different adhesives last night for the glareshield covering, the first item on today’s agenda was the finished that job.  I had stupidly gotten ahead of myself and removed the inside plastic covering yesterday, in order to be able to work better down in the tight corners at the front.  So, I taped up a bunch of newspaper on the inside of the canopy, to mask the bubble against any overspray.  Feeling sufficiently masked, I sprayed some Super 77 on the glareshield, and a coating on the backing of the fabric, waited the appointed time, and stuck them together.  I did have some troubles with the fabric sticking to the newspaper in the corners, duh…I knew there was a reason I had planned to not put adhesive on the fabric.  Sigh.  In the end, though, it stuck down well, and laid nicely.  It appears that even with my newspaper mask, a couple areas of plexi got a light fogging of overspray, aargh.  I’ve read through the VAF threads about canopy oversprays & cleaning, and sent off for some supplies from Spruce.  This too shall pass, with some elbow grease.

With the fabric in place, I inserted the snap bushing and GPS wire…looking good.

Next task was soldering the ELT connector, so I climbed into the baggage compartment again with tools & supplies.  Easy enough, then I made the LED test tool specified in the manual, which lets you see if the GPS signal is being received by the ELT.  It was, so I buttoned that install up; if I can remember to bring my modular crimpers home from work tomorrow, I’ll be able to put a bow on the ELT installation and cross that off the list.  I also ordered the batteries for the remote units today, having failed to find them at 3 local stores that carry camera batteries.

I decided that for whatever reason it was time to set the lengths of the control system pushrods, so I moved things around enough to fit the empennage.  I also primed some spacers and things that needed priming, part related to the empennage attachment.  Bolted on the HS and mounted the elevators.  Decided to fit the HS tips, so I had to do a little bit of trimming, and cleaned up the stepped edge to a nice crisp line with files, before positioning and drilling.  A couple trips in and out of the tailcone had the pushrods adjusted to get full stop-to-stop deflection of the elevators, hitting the travel stops at the elevator end rather than the control column end.  I measured the travel of the elevators to verify it was within spec, and it was.

Since I had the elevators rigged up, I figured I would connect the trim servo and configure it in the VP-X and EFIS.  That was a simple proposition, but I found that the pins for the up/down trim commands into the VP-X needed to be reversed opposite of what’s indicated on the load planning document (ie, 18 down, 19 up).  Once the correct motor polarity was set, the buttons in the software caused the servo to move correctly (“move up” moved the tab down for nose up trim), but the stick switch was running opposite that.  I tested the pins to be sure that I hadn’t reversed them accidentally — I hadn’t, the one marked up was indeed grounded when the up trim switch was pushed.  Swapping the pins at the input of the VP-X allowed it to run as expected.  Not sure what’s going on here, and I’ll be sure to double-check this system later to be sure it’s functioning properly, that I didn’t just have a bad brain day and set it up backwards.  Once it was running right, I measured the travel of the tab to be in-spec, as well.

Finally, mounted the VS and rudder.  Connected the rudder cables to the rudder horn.  Looks like I’ll need the connecting links to be around 2″ long — now, where to find the steel bars that they’re made from…  The rest of the empennage tips will get fitted next, I think; a little fiberglassing practice to close them out, then those surfaces can come back off for storage until final assembly.