Joshua's RV-9A Project

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.

Amid the craziness of this week and next, I made it out to the hangar for a couple hours tonight.  Worked on a couple of punch-list items.  First, I’d brought the electrical toolbox, so I was able to extract the old sockets from the taillight molex shell, and insert the new ones.  Then, install the taillight to the rudder and test both nav & strobe functions.

Safety-wired the pitch trim hingepin in place.

Dimpled the screw holes on the bottom fuselage skin, that overlap onto the wing; these would be impossible to dimple after the wings are installed.

Measured for and fabricated a closure plate for the forward part of the nosegear slot in the bottom cowling.  I forgot to bring any scotchbrite to the hangar though, so didn’t get it primed or nutplates attached, though all the drilling/deburring/countersinking is complete.

Back at it today, before another night at work.  Had two visitors at the airport to look at the project and talk.

• Crimped new Molex sockets on the taillight wires.  Forgot the extractor, so couldn’t take the old ones out of the connector shell to replace ‘em…
• Finished installing the elevators, and connected the pushrod and center bearing.
• Installed the rudder and connected the cables.  Some small tweaks to the rod ends and the aft edge of the fuselage and VS skins to eliminate some light rubbing.

At this time, the empennage is fully installed, save for the taillight and some tweaking to the pitch trim servo connector.

Popped out to the airport again tonight:

• Removed the spiral wrap from the taillight wire and replaced it with expandable sleeving, in an effort to keep the weight down in the rudder.  This required removal of the Molex connector, which we be reattached tomorrow.
• Crimped a ring terminal on the taillight ground wire.
• Installed & torqued the last VS attach bolt with the adel clamp and ring terminal.
• Hung & pinned the elevators.  Discovered the collection of special washers needed to install the center bolt must still be in the shop at home.
• Verified operation of the pitch trim servo.

Had the day off work today, and with the list of concerts to edit temporarily down to none, it was off to the hangar.  First, though, it took almost 2 hours to sort through, collect, and pack up everything that needed to move from the shop to the hangar.  On the way, stopped at Menard’s a picked up a rolling toolbox and a plastic shelf thing that were on sale.  After setting those up (could already use a second shelf thing), and putting things in their place, my corner of the hangar is becoming a workspace.

Popped off the top cowl in order to re-install the dehyrator plugs after baking the silica gel.  Adjusted a couple of the camlocs on the top that were too tight, and installed the spring on the oil door.

Climbed way back into the tailcone to install spiral wrap on the wire bundle that runs aft, for additional protection against chafing, should it rub against the skin between the ziptie bases.  Also wrapped the taillight wire bundle as it passes through the aft bulkhead and through the rudder.

Installed the HS & VS, torqued & marked all bolts — except the one that also attaches the case ground for the taillight, since I forgot to bring the crimper & ring terminal for that wire.

Removed the rod ends from the flaps and reinstalled with new lockwashers and blue loctite.

Another warm day (but this time breezy and hazy as well).  Trying to cross things off the list…

First on the agenda: loaded up the empennage and moved it to the hangar, where it will wait with the wings until final assembly.

Next, set up the day’s fiberglass job.  Added a couple plies to the nose flange layup from yesterday, to give it more stiffness.  Closed off the inboard ends of the cooling inlet ramps with a 2-ply layup.  Added flox to a couple spots and deep voids.  Again today, I meant to get two rounds done, so one could cure overnight, but ran out of day.

Spent awhile fussing with canopy seals.  The edge-gripper bulb seal I wanted to use on the front seems a bit too thick, as it’s interfering with the closing of the canopy — the latch requires immense force to actuate.  So, that was removed for now.  I added the same bulb seal to the side rails, and that also cause latch trouble, so I ended up slicing the bulb in half for about 60% of the length of the side rails.  It looks ragged when open, but seals fine when closed.  This is easy to replace later — I’m searching for a smaller bulb, but the 3/8″ is the smallest I’ve found so far.  I may have to explore using foam strips or something.  Also ran into trouble with the rear rollbar seal, again, difficult to close & latch.  Will explore more seals; it seems this is a spot everyone struggles to make work.

On to the “little stuff:”

• Slipped some clear tubing over a couple fluid lines in the tunnel to prevent any possible chafing from wire bundles (clearance is fine, but vibration does things…)
• Installed the fuel selector & torqued all the fluid fittings in the center tunnel.
• Installed the fuel pump and torqued those fittings.
• Installed the metal plug in the hole that provides access to the nose leg bolt.  Sealed up with a good layer of firewall sealant on both sides.
• Installed the bolts on the RH lap belt, having received my order of hardware from Spruce.
• Finished off the firewall wiring passthrus per instructions, since wiring is complete.
• Torqued the forward bearing on the aft elevator pushrod.
• Checked that all bolts on the flight controls were torqued, and torqued them where they were not.
• Swept the shop and put away tools, brake bleeding stuff, and so on.