Joshua's RV-9A Project

Not perhaps the most auspicious of milestones, but I did put the first avgas money into the project today…5 gallons worth into a new blue fuel jug, for the sake of fuel system testing.

But first…most of the day was actually spent on or near the wingtips.  I spent awhile shaping some foam ribs to go inside the tips, to strengthen, eliminate oil-canning, and hold the proper shape.  Once I had one side looking good, I marked the spot of each rib, traced them on fresh foam, and cut a matching set for the other side, which provided a good starting point.  After setting the location of each rib for proper shape of the tip, I mixed up some flox and buttered the edges, set them in place, and pinned the tips back to the wings to hold the proper shape & alignment while the epoxy cures.  I’ll pull them tomorrow, add more flox to fill in any gaps, and lay a strip of glass tape along the edges of the larger foam rib, for good measure.  (No photos of this because I was covered in foam dust and epoxy.)

Wingtips curing nicely, I moved on to the lenses which cover the lighting “bay” in each tip.  I remembered to bring the replacement lens this time, and I had dropped the belt/disc sander off the other day, so all the parts were in place.  It’s nothing too difficult, just a lot of repetitive and time-consuming fitting, sanding, filing, fitting again, and repeating the whole process.  Since it fits a curve at two points, each bit you take off changes the fit of the rest of the lens, so it took awhile to get it right.  Once satisfied, I drilled a #40 hole at the corner, top & bottom.  Clecoed to test fit, then enlarged to #27 for a #6 screw, removed, and drilled/countersunk holes for nutplates.  Those will be installed tomorrow when the tips come off after the epoxy cures.

Moving inboard a bit, I removed and cleaned the lenses for the landing & taxi lights.  They were quite dirty on the inside surface, since the wings were stored leading-edge down in the cradle.  Shiny and clear again now, though.

Cut some lengths of acrylic tubing from a 6′ piece I had ordered a while back, and smoothed the ends.  This will become a fuel dipstick for checking the tanks.

On to some engine work in preparation for an eventual first engine start…

• Removed the paper towels that I’d stuffed in the fuel servo inlet to keep out bugs/etc.
• Used a syringe to apply some Mouse Milk to the exhaust ball joints.
• Connected the computer to each Pmag in turn to verify the timing (also cross-checked with the indicator lights on the ignition body), and make sure that the advance was limited to the “basic” setting (35 degrees).  Once the engine has been broken in, we’ll dial this up to the more advanced 40° setting, which should help the engine run more efficiently.  The two ignitions are timed nicely together, and they are timed to 1° after TDC, rather than TDC directly.  Based on the manual, I’m going to leave this be for now, since they do suggest that it be up to 3 degrees after TDC for lightweight props, which mine is.  We can tweak later if necessary.

Later on, I drove down to the fuel pumps to fill up the aforementioned can with fuel.  Poured some into each tank (BTW, I hate the newfangled gas nozzles that you have to push down against a spring to keep the fuel flowing…and their vent inlets are so tiny that the flow rate is pathetic), sloshed it around by rocking the plane, then drained it back out again — the idea being to get as much junk out of the tank as possible.  Filtered it back into the can, and poured from the can back into each tank.  Sumping into a tester showed clearer fuel this time.

Disconnected the fuel line from the servo inlet, but I didn’t have the fittings with me to extend it anywhere useful, nor a measured container to pump fuel into, so I just capped off the line and servo inlet for another day.

Three project visitors today; Art (Lancair) from the airport brought his Australian pilot friend (Jabiru) around to check on the progress, and Bob Collins (RV-7A) dropped in later in the evening to chat and take a look, while on a flight around his test area.  As the sun was setting, I caught this neat picture out of the hangar door, with the cloud shadows…  A good day.

The replacement nav/strobe assembly arrived, along with the replacement wingtip lens.  My hangarmate fixed my up with an engine hoist and sling for raising the nose to work on the nosegear.  So, time for a night at the hangar.

Trimmed the leads on the new nav/strobe, and crimped on Molex pins.  Tested it out for awhile, and it stays in sync with the others, so — problem solved.  Removed the old unit from the wingtip and installed the new one.  The faulty one will be on its way back to AeroLEDs tomorrow morning for an autopsy.  While I had it off, I grabbed a photo of the mounting bracket installed.

Easily raised the nose with a sling around the prop spacer, hooked to the engine hoist.  I removed and disassembled the nosewheel and fork, cleaned the axle shaft/bearing seal mating surfaces, and installed the axle according to the directions (tighten the ring until the bearings don’t rotate with the wheel), then tightened the screw on the preload-setting ring.  Set that aside for a bit, while I attended to the fork assembly.

Cleaned & greased the bushings in the fork, along with the spindle.  Slid the fork on and installed the washer stack and big nut, then tightened it down with the giant (3/4″ drive) socket/ratchet, until I had the desired figure on the fish scale.  My cheapo fish scale I bought isn’t perhaps the pinnacle of professional measuring devices, but it got the job done.  On the advice of those who have gone before, I set the breakout force high (26lbs), so it has room to drop as the parts wear in during initial use.  Once I had that set, I drilled the 1/8″ hole across the spindle, removed the nut to deburr, and reinstalled the whole stackup with cotter pin.

Reinstalled the nosewheel to the fork, torqued and marked everything, and we’re done.

Deburred, countersunk for, and installed the wingtip aft closeout ribs.  I added a nutplate to each one for securing the hinge ends, though I’m not sure yet exactly what that will look like.  They were installed with a fillet of flox, after roughing up the surface, and blind-riveted in place.  The rivets will be covered with micro filler eventually, so the pops are not a cosmetic issue, and I was able to reverse the ribs and place the smooth side inboard this way.

After that, sat in the seat with the engine manuals and configured the limits and alarms in the EFIS.  Nice evening outside, quite cool (~60°) considering in 36 hours the heat index is predicted to be over 100°…

Yup, another day working on the wingtips.  I’m not at all convinced that this hinge method is easier, as some said, than doing all the nutplates.  I’m reserving judgement on the outcome until I see it all done, though.  One upside that I do see is the ability to get the tips “done for now,” and then with relative ease, remove them for additional fiberglass finishing later on.  That’s a good thing.

Drilled, mounted, and wired the AeroLEDS wingtip lights.  I lined the wingtip cutouts with strips of aluminum tape to give it a pseudo-mirrored look; the glasswork underneath isn’t perfectly smooth, though, so there are some visible seams and lumps.  I expect this will be somewhat temporary, and will be redone later with tape over smoother glass, or perhaps a thin sheet of mirrored plexi.

Discovered that the right (green) light assembly seems to have a problem with the strobe sync; while the left and tail strobes flash together, the right one drifts in and out of sync.  Swapping left & right, the problem stays with the unit, which indicates a fault with the unit, and not with the wiring.  (Update 6/25: AeroLEDS agrees it sounds like an internal problem, and is sending an advance replacement for the suspected defective one.  Defects happen, that’s expected, and it’s good to see a company handle it this way.)

Attempted to start fitting the tip lenses, and promptly put a big crack in the right one with the bandsaw.  Dang.  New lens on order, and we’ll start over with that.

On to the tip hinges…did all the necessary deburring and countersinking (yawn), and was able to get the hinges riveted to the wings and wingtips, by staying at the airport way too late for a “school night.”

Work occupied most of the day today, but got away for a bit in the evening to check up on yesterday’s epoxy.  As expected, it was cured, so I removed the clecoes and spent some time shaping the wingtip TE’s.  Once satisfied, mixed a small batch of micro and filled the holes where the clecoes had been.

My order from Avery came today, so I have the Perma-grit countersink and sanding block…I was so impressed with the stuff when I borrowed a sanding block that I had to have my own.  Recommended, wish I’d had this thing when I was doing all the fiberglass earlier.  Hopefully I can get most of the rest of the wingtip install knocked out tomorrow after church.

Stole a day from work and spent it at the airport instead.

Marked and drilled the hinges to the wingtips, using the holes match-drilled yesterday.  Those holes are used to secure the inboard hinge side, and another parallel row was added to secure the outboard hinge side.

Cut the flange off the wingtips in the areas that have hinge underneath.  The resulting fiberglass strip (which matches the varying thickness of the tip) is then used as a spacer between the inboard hinge and the wing.  Used a straight sanding block to true the edge of the wingtip.  When cutting, I stayed to the inside of the molded joggle, so that the small gap left by the blade kerf is hidden as much as possible under the wing skin.

Fit the hinge halves and spacer strips to the wings, and pinned the tips in place.  Checked adjustment and decided to go ahead and bite the bullet on fixing the TE alignment, so I cut the TE’s open on both tips (which were out of alignment by the same amount, around 3/16″ low).  Moved them where they belonged and drilled 3 holes in the TE, then clecoed together to hold the alignment.

Monkeyed around with the wingtip ribs for awhile; I modified the aft ribs (which close out the part of the tip visible outboard of the aileron) to be shorter so as not to interfere with the hinges or my big foam rib.  After careful adjustment and fitting to ensure the TE and aft end of the tip were well-aligned with the neutral aileron, I drilled the rib to the tip.  This locks the alignment in place.

Trimmed the hinge pins down to a reasonable length; they’ll be trimmed again and bent to provide a method of securing them to the aft rib, but there was tons of excess length.  Now I don’t need to worry about snagging & bending them as I walk around the plane.

All that done, and Allison having brought out my box of fiberglass supplies & epoxy, I mixed up some flox and laid a thick line inside the TE, then re-clecoed everything in its proper place.  Smoothed and scraped the excess that oozed out, and left it to cure overnight.  I’ll pull the clecoes and then fill the cleco holes with more epoxy.

I don’t want to disturb the tips until the epoxy cures, so I worked on other things…adjusted the inboard “ears” on the flaps, to make them sit flush against the bottom fuselage skin, and fooled around with the EFIS for awhile.

Heard Bob Collins (RV-7A in phase 1) making traffic calls in the pattern and stuck my head out in time to catch his takeoff.  (This morning he has a post up about the round-robin evening flight).  A nice night, so I popped the big door open a bit to get some fresh air while sweeping up the hangar.

Stayed too late at the airport tonight, trimming, shaping, aligning and drilling the left wingtip.  Then went along with a rivet fan spacer to mark & drill the added “in-between” holes.  The left tip’s TE is below the aileron by the same amount as the right tip was, about 1/4″.  Since they agree so well, I rechecked the aileron alignment again…still good, so the tips are low.

Let the wingtip fitting begin.  Sanded down the inside edge of the right tip, along with the foam rib to make it fit.  Once the tip fit properly into the wing, I drilled it to the wing using the prepunched holes in the skin.  I’ll drill more holes between those to secure the hinge eventually.

I have, as seems typical, a mismatch between the trailing edge of the tip and the aileron.  This will be fixed by splitting the TE and reglassing it at the proper angle before locking in place with the inner metal rib that is placed at the aft end of the tip.

Also installed the stick boots and labelled the data mark switch installed yesterday.

Not a ton of progress today, because I switched vehicles with Allison and in doing so, forgot to load up the stuff I needed to get started on either of the two major projects I was considering.  So instead, I worked on some smaller stuff.

I’m not using two of the three switched aux inputs to EFIS 1, and I want to have some way of marking data in the log files during flight test (for use in calculating performance or looking at some specific occurrence in more detail).  I checked the logs files and it turns out that the state of the inputs is logged.  So, I decided I would install a simple toggle switch that I could flip to mark data, which I could find later by looking at the logged state of the input.

I have a blank panel I made to cover the open mounting tray for EFIS 2, so I drilled a 1/4″ hole in it and mounted a miniature toggle.  Opened up the D-sub connector on the EFIS and swapped the pin in (the other side of the switch is connected to ground).  I programmed the EFIS to display “Data Marker” on the screen when the switch is on.  It’s not super pretty, or match the rest of the panel, but it is not intended to be a permanent install — just for gathering test data.  I’ll remove it completely when I install the second EFIS someday…unless it proves to be amazingly useful for some reason beyond my expectations.

Decided for selfish reasons to do some work on the interior — secured the seat pans with several screws each (they’ll be removed for inspection again, so no reason to put them all in…it will be nice to have a seat, though, to do the engine runs).  Pulled out the seat cushions and installed the velcro patches on the seatpans.  I need to find the stick boots…

The rest of the session was back on the wings.  I made a pair of foam ribs that match the airfoil shape, to use inside the wingtips.  Also looked at the wingtips to see how they would need to be trimmed, and swapped around some pieces of hinge in preparation for mounting the tips.

Moving to the inboard end of the wings, I deburred & dimpled the screw holes in the wing root fairings, and mounted them in place.  I marked a line 5/16″ or so from the side of the fuselage, down the entire length of the fairing strip, then removed and trimmed to the line.  Filed the edges of both strips, and brought them home to finish the edges on the scotchbrite wheel.

Milestone: not only is it our 6th wedding anniversary today, but I also crossed 1800 hours logged on the project.  That’s an average of 300 hours per year…thank you, dear, for tolerating & supporting this crazy idea of mine!  We’ll go flying soon.

Spent much of the day at the airport, and was able to knock a number of things off the list, some of them pretty big.  With today’s progress, the end of the project seems attainable.

Most of the day spent working on flight controls.  First thing to be done was deal with the ailerons, specifically the pushrods.  The holes in the rear spar needed to be opened up more to prevent the pushrods from rubbing there, so I carefully enlarged them with files, Dremel and scotchbrite.  After several refits of each side, I had it looking decent, and spot-primed the holes and pushrods where the primer had been scratched.  While I had the ailerons detached, I also riveted the aileron stops to the hinge brackets.

Once the ailerons were installed and secure, I re-checked the rigging that was done during wing building: the length of the bellcrank-to-aileron pushrods.  I bolted the jig in place on the bellcrank, and verified that the ailerons were centered on the chord line (marked by tooling holes in the rib).  They were, so I moved to the next step — setting the final length of the bellcrank-to-stick pushrods.  To do this, I jigged the left bellcrank, and adjusted the pushrod until the stick was vertical.  Then, moved the jig to the right bellcrank and adjusted that pushrod, watching for the left aileron to return to it’s jigged position.  Once that looked good, I double-checked both sides again by moving the jig from side to side and measuring.  When all was tweaked and ready, I tightened down the jam nuts on the pushrod to lock it in place.  Then, torqued the bellcrank bolts.  Verified that there was “twizzle” (available range of motion in the rod end bearings) in all pushrods at all extremes of travel; we don’t want any of the rod ends to be at the end of their range,which causes a twisting force to be imparted to the pushrod.

Ailerons done, flaps were next…during installation, I found that a thin strip of aluminum needed to be trimmed from the “ears” at the outboard aft edges of the belly skin, so they did not rub against the flap hinges.  Pinned the flaps in place and checked/adjusted the pushrod lengths, then tightened jam nuts and installed to the flap actuator.

I will say that I’m quite happy with the way the control surfaces came out…the ailerons and flaps line up nearly perfectly at the split.  Some people have not been so lucky.  (Karma being what it is, this means I will have a bear of a time getting the wingtips to fit correctly…)

With all the controls surfaces now installed and rigged, I measured the angular throw on each, and compared it to the design throw in the manual.  As the table shows, we’re within spec on most things, and the ones that are out are out by only tenths of a degree:

Lastly for today, spent awhile wrestling with the wing root connectors, to secure them so they don’t flop around during turbulence or maneuvers — both to prevent distress to the wires, and to prevent annoying “clunk” noises in flight.  Because the geometry is a little different from side to side (due to my routing of the pitot line), I ended up with different solutions on opposite sides.  Both make use of zipties and ziptie bases, and both required alternating between working in the narrow gap between the fuselage and wing with forceps and magic fingers (using the side of the fuselage as a mirror), and shoving my entire arm into the wing through the inboard inspection hole (ow…).  I did emerge victorious, if slightly bruised.  I like the CPC connectors, but if I were to do it again, I would not use them here.  I didn’t realize just how narrow that gap is, and it’s not possible to extract the connector for service or to add pins, etc.  I should have used D-subs, a bundle of Molexes, or some other rectangular connector that would fit through the gap (the ones used on the VP system may work).  If these connectors ever needs service, it’s likely that I will need to cut them free from the entire bundle and replace them with another type of connector.  (Thankfully, I left a service loop on both sides, so that would be possible.)

Two major projects remain: wingtips, and the nosegear.  (Plus gear fairings, of course, which will be delayed until after flight.)  If I could find a spring scale to buy in town, I think the nosegear would be easy to knock out in a day.  After those, it’s just a laundry list of little things to get ready for flight.