Joshua's RV-9A Project

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.

One more major checkbox is checked tonight…the wing join is complete after a couple hours at the hangar.

Unbolted and removed the fuselage side tank attach brackets, then drilled the tank side for the stubby nutplates called out (after hunting them down, of which there are only two).  Spot primed and riveted the nutplates on, then reinstalled the fuselage side brackets, installed the -4 bolts as described in the plans (not fully torqued, only until the washer is held fast), and safety wired them.  That completes the installation of all the wing join bolts.

Brought supplies to the airport, so I was also able to trim the pitot lines in the belly, and join them with a push-connect union.  While I was in there, I also added some spiral wrap to the headset cable bundle, where it passes near the flap actuator.  Not alot of motion here, but this should prevent the possibility of any chafing.

I’m considering not using nutplates for the wingtip attach, and instead doing something that’s been used by several people before me, and well-documented — affixing the tips with hinges, in the style of the cowling.  It’s supposedly 1) less tedious than doing the 80-some nutplates, 2) looks smoother, since there’s no obvious fastener line/no pillowing between screws, and 3) easier to install & remove for maintenance or whatever (a small issue since the tips are rarely if ever removed in service).  I understand how they’ve done it, and it seems straightforward, the only thing that concerns me is how to account for the kerf removed when trimming the fiberglass piece out.  Still researching.

Final assembly continues.  Finished off the wing bolts — all the -4′s for each wing, and the rear spar bolts.  Also installed the screws along the belly skin-to-wing joints.  Vacuumed the crud out of the seat pan area, and reinstalled the comm antennas.  Trimmed & connected the AOA pressure lines.  I need to grab the pitot union connector from home to hook that up.

Found my latest mistake, though: I was supposed to install a nutplate on the tank attach bracket before mounting the wings.  Oops.  The brackets in question are well-attached to the fuel tank, but I should be able to remove their mates from either side of the fuselage for access, drill and rivet the nutplates, then reinstall the fuselage brackets and we’re back in business.  Less than an hour, I’d estimate.  (I would have done this today, but didn’t think of it until now…in my mind, I needed to email Van’s to see if a different bolt arrangement would work here.)

Massaged the RH fuel feed line to adjust its position in relation to the tank nipple.  Removed the vent line stubs from both sides and replaced them with new, longer versions.  Tightened and marked feed & vent lines on both sides.  Adjusted the tension bolt on the fuel caps.  Installed ring terminals on the fuel level sender wires, and connected them to the senders.  The fuel system is now complete.

One by one, removed the four bolts holding the VS to the HS forward spar, and added a washer under the bolt head.  This in response to consensus on a recent VAF thread after someone found a crack propagating from one of these slotted holes.  The washer’s purpose is to provide a larger bearing area for the clamping force of the bolt.  Retorqued & marked.

Loosely connected the aileron pushrods to the bellcranks and control column, and inserted the smaller pushrods from the rear of the wings.  Pinned the ailerons in place and fooled around with pushrod positioning, stops, surface throw, etc.  It’s nearly right as is, but I want to bring a round file and Dremel sanding drum and “customize” the pushrod holes a wee bit more, to make it just right.  I also need to rivet on the aileron stops, which are only clecoed right now.  Once that’s done, the ailerons can be installed and we can move on to flaps.

Out to the airport for a few hours on a nice day today; Allison came along for the ride so I put her to work, helping attach the wings.  I could have waited a few more days, but at some point, it’s time to “fish or cut bait,” as they say — so we did it.  I scrounged up some sawhorses from the back of the hangar, and padded them with foam; I think these sawhorses must have been previously used for this task, as one was cut shorter than the other, approximating the dihedral of the wing.

Sawhorses in place, we lifted the right wing from the cradle, set it up on the sawhorses, greased the spar stub, and slid it into place.  With me inside the plane inserting the bolts and adjusting the inboard end, and Allison at the far end of the wing moving or wiggling it in whatever direction I requested, the whole process was relatively painless.  With a collection of mallets, hammers, and wood blocks, all eight bolts went in without hassle, after being greased to assist insertion.  I read through a bunch of build logs this morning and took notes to make sure I wasn’t overlooking anything, and all the washers & etc ended up in the right places.

Regroup, resupply, and repeat for the left wing, then drop the rear spar bolts in for support, so I could use the wing walk for getting in & out of the cabin (which was repeatedly required).  With both wings pinned in place, the smart level agreed that both wings had equal dihedral and angle of attack (as they should; the wings were mounted previously and carefully measured & drilled).

Now for the fun part — placing & tightening the nuts on the bolts, especially the bottom ones, where access is superbly poor due to the position of the main gear weldments.  Luckily, I came prepared…  I found that my hangarmate had a set of special open-end wrenches with heads at a more severe angle, similar to this (Snap On apparently calls this a 4-Way Angle Head; MAC Tools just calls it an Angle Head; I’d never seen one before):

(The head on the right is the one that’s used on the bolts here.)  There were two sets, and the ones I ended up using had a slightly thinner body on either side of the head, which made a difference, as it was far easier to remove the wrench once the tightening was complete, on the bottom outboard -7 nut.  Anyway, these wrenches made the hassle of accessing the nut a non-issue.  [I will try and remember to look at the actual brand of wrench I used and post it here for reference.]

The angle head wrench wasn’t the entire solution to the problem though — after a few long minutes of turning the first bottom bolt with a ratchet, two clicks at a time, I decided there had to be a better way.  And there was — I took my air ratchet and set it up with the necessary adapters & extensions to use a 6-point socket; I wasn’t sure the air ratchet would have enough power to drive the big bolts, but it did.  With the angle head wrench on the nut, and the air ratchet on the bolt, it was simple and easy to snug the bolts down.  Reverse for the top, and drive the nut while holding the bolt head (NB: unlike the smaller fasteners we’re usually using on the plane, the bolt head and nut are different sizes here!)

Once I’d snugged down the large bolts/nuts for each side, I used a torque wrench to finish tightening them down; it required about a turn on each, which wasn’t bad at all.  Though it was perfect for these -7′s, I won’t let the air ratchet go all the way on the -4 bolts, as it may overtorque them — better to stop early and hand-tighten the last couple turns to the required value.  Torque seal applied, and we’re done with the large bolts.

With those in, the wings are secure, and it was time to make some notes and head for dinner and home.  I should be able to get back out tomorrow and install the rest of the nuts & bolts.

The main fuel lines will be fine, but the short pieces of tube that comprise the first piece of vent line coming off each tank will need to be replaced, as they’re around 1/2″ short on both sides.  Obviously we trimmed them a bit too far.  Easy enough, if annoying, as long as I remember to take the tube stock and tools to the airport.