Joshua's RV-9A Project

More sanding, and nothing but sanding.  Sanded down the coats of epoxy that were applied to the canopy fairing last night; I think it’s going to come out alright.  Masked off the canopy and Allison helped me move it to sawhorses to wait for spraying.

Sanded down the empennage fairing, so that can be primed too, though there are a couple spots that need a bit of micro and followup sanding.

Spent the rest of the session starting work on the emp tips: final-drilling the holes, dimpling/countersinking, and sanding for primer.  One of the elevator tips needs a little micro along the seam, and the rudder top fairing will, too.  Hoping to get the rest of the tip work (just the rudder bottom) done tomorrow and apply some micro, then spray all this stuff midweek.  I think it’ll be a mental boost to have all the glasswork except the cowling “done” (for now, and excepting gear fairings which will probably wait until after first flight.)

Began the day with some excitement; nearby -9A (and now -10) builder Mike Behnke was gracious enough to bring his plane down to Red Wing this morning so I could have my first RV flight — a great one!  The day was warm, calm, and relatively clear, and Mike’s plane looks and flies great.  My only experience being in 150/152/172 types, the stick-and-pushrod controls were a new thing, and a joy to fly; no slop in the control system, and just a bit of pressure required for control.  We did some turns, stalls, a bit of sightseeing, and Mike demonstrated an autopilot-coupled GPS approach.  Also got to see the AFS screens in flight, as his panel is practically identical to mine (both equipment and layout).  We also chatted about fiberglass, transition training, inspections, first flights, and so on.  Many thanks to Mike for the opportunity!  It’s another inspiration to work through the endgame of my project.

On my way out of the airport, I stopped by the hangar and pulled the fuel caps from the wings (and taped over the filler holes), as I’m considering sending them in to be engraved with the required markings, rather than using a sticker.

Into the shop after lunch, I spent several hours sanding the micro filler on the canopy fairing.  It turned out pretty well, and I think I’m going to try and move ahead with it.  To that end, I squeegeed on some straight epoxy to seal the micro and fill pinholes.  I’ll add another layer or two, then sand and see where it sits.

I used the excess epoxy to seal the inside of the emp fairing.  I’m hoping to get the rest of the emp tips ready to spray this week, then spray a whole batch of glass one night.  Once the tips are done, the emp parts will move to the hangar.

Drilled the dataplate to the fuselage — I’ll send this in for engraving with the fuel caps.  Also located some 3/32 pop rivets to attach it. Since I don’t know when the inspection will be, I’m just going to put 2012 in the date box; this field isn’t even required.

Then I took a look at the top hose from oil cooler to engine; I think the bend radius on this hose is too tight, and I’ll need to order a longer hose, change the fitting on the engine, and reclock the fitting on the oil cooler, to allow a more sweeping bend in the hose.  It’ll be more in the way of filter changes, but don’t want to take any chances with an oil hose collapsing.

Added a silicone boot to the oil temp sensor wire; more for vibration support of the wire than for short-circuit protection.

Stuck a label on the brake reservoir, indicating what the thing is, and the spec of the fluid it’s filled with.

Traced the spinner diameter and used some geometry to trisect it, in preparation for making the prop cutouts.  Still need to figure how I’ll determine the shape of the cut, not owning one of those curve-finder pin apparatus.

Countersunk & installed the lower HS fairing strips.

Installed an alternate static placard on the panel.

Re-fit the cowling and set the depth of the bottom cowl camlocs.

Fussed with the cowling, bulkhead, and spinner a bit, and came away not feeling so good.  The spacers I used when fitting the cowl must have been off by just a touch, because it now appears the cowl is shifted off to the left by a small amount.  The result of this is that the desired 1/4″ gap behind the spinner measures 1/4″ at the left side, but only 1/8″ on the right.  If the cowl hadn’t already been fit and drilled, hinges cut, etc, this wouldn’t be that big of a deal, just slide the right side aft.  As it is, I can see two options: 1) remove all the hinges, camlocs & such, fill the drilled holes, and refit the cowling, or 2) install the top skin, camloc strips, and camlocs (because I already drilled the camloc receptacle holes to full size, I can’t just cleco the cowl to the strips any more), attach the cowls in position, and rework the front of the cowling to provide the desired gaps.  The cowling might also be sitting a bit high, given the common recommendation to set it low to allow for engine sag.

All in all — Ugh.  I wasn’t looking forward to the fiberglassing to begin with, and this further dampens my desire to get started.

EDIT: After some reading, apparently this is not uncommon, and an accepted way to deal with it is to add layers of glass to the aft side of the cowl spinner area, and sand back until the gap is even all around.  Spots where the gap is too large can be built up with filler, and the nose reshaped as necessary.

Didn’t get part of Friday off from work as I’d hoped, but today I proceeded with the weekend plan of highlighting a bunch of items on the punch list, and knocking them off…

Mixed up a batch of firewall sealant (don’t smell that stuff…wow) and sealed the perimeter of the firewall sides and bottom, and a fillet in the lower corners.  The top curve will get done later when the top skin is put on.  Let that tack up, then clecoed & riveted the sides and bottom, along with the shims, hinges, and camloc strips.  By moving the exhaust stacks and using a variety of yokes, I was able to easily squeeze every rivet but the centerline bottom rivet, which was unsqueezable with any yoke from any angle.  That hole now sports a pulled rivet.  Once the camloc strips were on, the camloc receptacles were added.  Done.

With the lower edge of the firewall complete, I added the metal portion of the fuel pump vent line.  Done.

The metal fairing strips that run underneath the HS were next; drilled and tapped the appropriate holes in the aft longerons, drilled the strips, and test fit.  To see how the fit was, I added the HS back on for a moment, and marked the trims that needed to be made.  After several iterations, I had the 1/32 to 1/16″ gap called for in the plans, so the strips were primed.  Still need to countersink the strips, but Almost Done.

Removed the canopy strut attach blocks and primed/painted them.  While they were drying, I removed the blue tape that has been covering the canopy decks; underneath, I found (as I suspected) that some of the adhesive had become gummy, so that’ll have to be washed up.  Later, reinstalled the strut pivots, and reinstalled the assembly to the canopy decks.  Done.

Big job of the night: redo the intake studs in the engine sump so the nuts have enough threads protruding.  This required moving the exhaust stacks (again) and partial disassembly of the entire fuel servo/control cable works — not an easy task due to the limited room to swing a wrench; several of the bolts can only be turned one flat (1/6 turn) at a time.  Eventually, though, it was off, the studs removed, holes cleaned, and reinstalled studs to the correct depth.  Not much was really needed, only 1/8″ or so on each one.  Some of them ended up being a little longer than necessary, but there’s plenty of thread and the nuts are not bottomed, so all is well.  You don’t want to bottom the stud out in the blind hole, as it will stress the threads and can cause them to fracture.  I used a torque wrench to verify that the driving torque requirement was met, and installed with red loctite per the AFP manual.  Much reassembly later, we’re back in business, and the nagging “that’s not right yet” of those studs is gone.  Verified stop-to-stop movement of throttle and mixture.  Done.

Enlarged the drain holes on the fuselage to #19 based on talk that the #30 hole isn’t big enough, and (especially if any gunk is present) the surface tension of water will prevent it from draining.  Also added a drain hole at the lowest point of the fuselage (which is under the seats, and not at a bulkhead), and one under the fuel pump area.

Placarded the alternate static valve installed the other day, and remade the fuel purge and center cabin heat placards with white on black, which looks nicer on the black panel.  Also made black on clear labels for the extra PTT buttons on the fwd canopy decks, and for the pilot’s stick functions (PTT, Trim Up/Dn, and AP CWS)…I expect those will fall off over time and use, but my understanding is that it’s better to have everything labelled to the point of excess at inspection time.

Drilled and installed the fairing nutplates on the HS.

Countersunk and re-primed the top cowl camloc strips (oops).

Cut and attached the blast tube to the alternator with a double-wrap of safety wire.  I’m all ears if someone has a better way of doing this, but it’s reported to have worked.  Also rumors that the alternator doesn’t need it, but cooler is always better for electronics.

Tightened and re-saftied the dipstick tube, as it was weeping just a bit at the gasket, since the engine is full of oil now.

Installed the alternate static toggle low on the subpanel behind EFIS 1.  I bought a toggle switch guard to put over it, since the actuating force to open the switch (thereby venting the static system to the cabin) is quite low.  The guard needs a good strong push to open & latch, and it holds the valve firmly closed in the down position.  I sat in the seat and the switch is out of sight, though easy to reach under the panel.  It still needs a placard, though, because my labeller was too cold to print labels.  (It looks like the wire bundle is very much in the way, but it’s just a result of the camera location.)

Checked to be sure I’d run the remote output port from the transponder to the ADS-B connector (I had), as the need for that connection came up on a recent VAF thread again.

Wasted the rest of the night sitting in the seat playing with the avionics.

Removed the clecoes around the firewall perimeter, along with the lower cowling side hinges and shim strips.  Primed these and the camloc strips in preparation for riveting the firewall (after inserting sealant).

Removed the empennage; they likely will not go back on until final assembly.

Torqued & marked the rod-end bearings on the elevators & rudder.

Riveted the VS forward attach bracket to the VS, and riveted/bolted the rear attach angle to the fuselage aft deck.

Drilled/countersunk/dimpled the VS tip; set that aside with the HS tips to await fiberglass finishing.

Countersunk the emp fairing attach holes for tinnerman washers.  Drilled and riveted the emp fairing nutplates on the VS.  I’d like to get the entire empennage group tips smoothed, sprayed and riveted on, and take them to the hangar to stash with the wings.

Torqued & marked the brake line connections at the calipers.  The brake system could be filled & bled at any time.

Allison joined me in the shop for a bit to finish removing the tape gunk from the empennage fiberglassing adventure.  While she worked on that, I sanded the micro and shaped the edges of the emp fairing.  After fitting it back onto the plane, I’m pretty happy with the fit.  Now, I’m going to use this (and the emp tips) as a learning canvas for fiberglass finishing.  I have a box of PPG stuff here that I’m planning to use, which I chose because it seemed to be the most well-documented on the forums and build logs.

I also drilled the HS tips to #30, dimpled the skin, and countersunk the fiberglass.  These are ready for finishing, then attaching.  The goal with the fiberglass stuff is to get it to an acceptable level of finish and wearing a protective coating.  If it needs to be dealt with further, I can revisit it before paint (or let the pros make it shine as part of the pain process).

With the fiberglass dust (ack) cleaned off the workbench, I pulled the clecoes from the baffle airseal strips and installed the large-head pop rivets that hold it in place.

Finally, I installed the latest version of the EFIS software from AFS.  The problem where the screen blinks durin initialization when displaying the VP-X status page has not been fixed.  I pulled the config files to load into the computer and update some things.  (Hint: Linux works better than Windows for editing these files, as the line breaks display correctly…no surprise, since the AFS box runs Linux internally…)

I’ve also been working on the paperwork side, having built an InDesign project and templates for the POH, and compiling the “best of” from several existing POH’s that others have shared on their websites.  There’s lots of specific information to research and fill in, and plenty of stuff yet to write.  Being a layout nerd and a perfectionist, it’s possible to pour hours into this part, too.

Trying to get the plane to the point where the tail feathers can be removed and stored, to allow more garage parking.

Fit the stock empennage fairing as best I could, which is essentially a ton of on-mark-off-sand-repeat, until it gets close.  Then I marked some final trim lines and sanded it back to there. Taped in place and carefully drilled #40 through the fairing into the open holes in the metal.

Next, to fill the little gaps that remain…  Taped up the metal surfaces and waxed them, and mixed up a batch of epoxy with micro and cabosil, slathered it on the inside of the fairing edges, and clecoed the fairing in place.  The idea is that the micro will fill the gap; once it’s cured, the fairing can be removed and the edges sanded pretty, then the rest of the finishing process can go on.

(Update: 55* in the shop is clearly not enough for efficient fiberglassing; the fairing took 4 days to set up completely, and that’s after pulling it off and bringing it in the house to sit.)

Also trimmed the layup on the cowling intake snout, and shaped it to be even with the intake.

Over the past two nights, spray-painted both sides of the steel links that connect the rudder pedals to the cables.

A very fiberglassy day, once again.  Also did a bunch of (more) reading on what primers and other coatings are required/recommended for finishing the glass parts.  I’ve identified the list that I would need if I were doing prep for parts that would be painted now/soon (PPG DPLF, followed by K36 or K38) — the part I need to sort out still is whether that is an acceptable stopping place for a plane that likely will not be painted for several years, or if some other coating/sealer/etc needs to be put on top.  I found that the K36 can be mixed either as a primer/surfacer, or as a sealer, where a base or clear component is added; perhaps that’s a good final step.

So, today’s work…sanded the epoxy coat on the HS/VS tips — that stuff is hard.  Which is as intended, really…but I was still surprised at the amount of work it took to sand.  These are now ready for the priming/finishing steps.  I need to get the rest of the empennage tips to this stage as well, then I’ll have a go with whatever process I settle on.

The next big job was to create the union between the lower cowl and the airbox.  Firstly, the front snout of the airbox needed to be trimmed back sufficiently to give clearance for the cowl to drop down vertically, so it can be removed with the prop in place.  This took several on-off-trim-test cycles with the lower cowl; I put the top plate of the box on the servo and trimmed that to fit, then trimmed the fiberglass bowl once the last trim point had been established.  I cut a hole through the middle of the foam blocks attached yesterday with a hole saw, then used files to work it out to the necessary size and shape.  During this process, I discovered that the epoxy I used yesterday to glue the two pieces of foam together was too hard for the job; the rear foam piece cracked off when the hole saw hit the layer of hard epoxy.  So, I made some measurements and fit another piece of foam to the aft side, using contact cement and a screw in each corner because I’m impatient and didn’t want to wait for it to set up.  That worked out, and I was able to shape a nice transition to the airbox.

With the transition duct mold done, I had to do a layup to form the actual duct.  Wetting out the cloth (2 layers of the Rutan bid) was easy, putting it in place inside the duct, and getting it to stay there, was another story, but I emerged victorious, if a bit sticky.  To finish off the inside, I cut another piece of cloth, some lighter, tighter weave stuff I got, and laid that up as the final inside layer, which should leave it a bit easier to finish than the relatively coarse cloth.  I secured this all in position and left it to cure.  Later in the day, I trimmed the long excess and brushed a layer of epoxy on the inside, as the first step toward finishing.  Sanding inside that duct will be fun…  Tomorrow, assuming it’s set up enough, I’ll remove the foam and lay up another layer or two of cloth around the outside of the duct to securely fix it to the cowl.

Spent a bit of time cleaning up the shop, stuffing the trash pile in the corner into the garbage can and sweeping, before moving to the next task.

I decided to tackle cutting and fitting the airseal fabric on the engine baffles.  Started by making templates of all the baffle tops from cardboard, then cutting 3″ wide pieces of fabric matching those curves.  Laid out a rivet pattern on both side baffles, and drilled/deburred.  Taped the fabric in place and marked the holes, then drilled them in the fabric on the bench–the fabric is tough to drill, and didn’t drill well in place.  Even on the bench, it didn’t really drill, just poked a hole through.  Some have had luck here with leather punches, though I can get clecoes and rivets through the holes, so I don’t know how critical that would be.

The side baffles are in two pieces, to match the fore/aft split in the baffles.  I made nice curved pieces for the front segment, but they needed to be cut once in place in order for the fabric to bend over properly.  One cut overlaps itself, but the other opens up a gap, so I made a gap filler piece for each side, as well.  The aft segment, which came next, is also in two pieces, and the right side is captured between the baffle itself and the bracket which is bolted to the engine case.  Laying the top cowl on, it seems like these will work.  I need to see what’s needed for adhesive when affixing these — I bought some Pliobond earlier, but for these which are riveted, perhaps just red RTV is the thing to do.  I have not yet dealt with the front baffle, since it needs additional trimming and figuring out the interface to the top cowl.

Also need to sort out how the airseal fabric works at the front of the airbox; it appears that it’s riveted to the outside of the airbox, and seals as best it can around the outside of the cowling duct, not the inside.  I made the second piece of foam the right thickness so that the foam very nearly touches the opening of the FAB as currently trimmed, and I’ll trim the fiberglass of the duct to that point before removing the foam, so that obtaining the correct gap between cowl duct and FAB will be an easy task of measure and trim.