Joshua's RV-9A Project

Worked against the weather today to get the wing skins primed.  While the spray gear was set up, the baggage wall pieces were primed and painted, as well.  Thinning the Rustoleum paint has been hit-and-miss, and today’s batch was a miss…I think it was thinned out too far, and the panels ended up with very heavy coats to get the coverage needed without pinholes…they have a different look than the rest of the interior; for now, we’ll let it go, since there are other inconsistencies, and these panels can easily be pulled out, stripped, and repainted later if it becomes bothersome.

Also finished wiring the internal parts of the wings, trimming the wires to length and crimping on the connectors for the landing lights and the D-sub for the autopilot servo, and terminating the leads to the pitot heat control board.  I later realized that I have not yet run cable for the OAT sensors which will be installed in the right wing to feed the EFIS boxes.  I also epoxied some zip-tie bases to the underside of the seatback bulkhead for holding the headset jack wires, and installed the baggage light strip under there as well, using it’s built-in adhesive strip.

Neighbor Jeff stopped by to check on the progress; it’s been awhile since he’s seen the project.  People who see it now say it looks like an airplane.

A collection of things happening in the shop today.  First thing up, finish the canopy sealing.  The excess Sikaflex was rubbed off the exterior of the top skin and the inside of the rear window and canopy (from gluing the spacer gaps), followed by removal of the rear window spacers and insertion of sealant into those gaps.  Smoothed those over with tongue depressors and all looks good.  Some canopy work remains, of course, but the plexi is in place (which was the big summer goal).

Before the gear can be put on the fuselage, the wings need to be fit, which was skipped earlier in order to get the canopy done in the warmth of summer.  In order to do that , the wings will need to be finished (bottom skins riveted on, which means that they must be wired and plumbed).  Out came bottom wing skins, which needed edge deburring and a few dimples made.  After those were done, the skins were etched for priming along with the rear baggage wall; unfortunately it was too windy to prime until after dark, so that’ll have to wait for another day.

Cleaned up the inside of the wings, which had naturally collected a layer of shop dust and spiderwebs, and set about running the various wires and tubes for the in-wing systems (pitot heat, lights, strobes, AOA, and autopilot).  Everything except the pitot tube was run inside the corrugated conduit which was installed during the wing build.  A hole was drilled in the conduit near the aileron bellcranks, to permit wires to emerge for autopilot and pitot heat; once these wires are in position, some RTV can be used there to prevent any chafing on the conduit edge.  The control module for the heated pitot was installed on the rib near the bellcrank inspection hole, which should allow access to hook up the pitot wires later on.  The pitot tube was secured underneath the aileron bellcrank with an adel clamp to prevent interference or chafing.  All the wiring and tube will terminate at the wing root in connectors, to allow the wings and fuselage to be fully wired in the shop, and easily joined at the airport later on.

Removed the canopy from the fuselage for eventual sanding to true up the back edge; I also need to read and see how wide of a gap is needed here to allow proper opening of the canopy.  Fit and drilled the canopy skirts, the countersunk/dimpled, masked off the area at the top which will get sealant, and primed the rest.

Measured out a section of LED strip light to go under the channel that runs behind the seats; this will serve as baggage lighting for loading/unloading in the dark.  The power for this will feed from the center of the strip, so I spooled off some 20ga wire and soldered it on.  While I was soldering, I also wired up the pigtails to the stick grip switches; the pilot’s grip got some expandable sleeving to keep all the wires in a nice bundle, as well.  Both grips’ wires will terminate in a connector at the base of the stick–either a Dsub or CPC for the pilot, and a 3.5mm mini-jack for the copilot, which will be easy to access to allow for stick removal.  I may also have a second PTT somewhere for the right seat, when the stick is removed.

Last but not least, I was able to find a good description of gluing a tip-up (illustrated, even) from Jim Ellis on the Matronics Wiki — I think this is the procedure I will use, minus the screws of course.  Fitting the canopy and then inserting the adhesive should be easier and less messy to handle with only two people, compared to applying the sealant bead and then lowering the canopy onto it.

Wired up and tested the map light panel, with the lights, switches, and dimmer module.  This panel will close out the bottom of the roll bar brace, and will receive power from the interior illumination circuit.  Two switches provide for independent control of left and right lights.  A single dimmer knob controls the brightness of both lights, via a PWM dimmer module.

Off-and-on in the shop today while working through other non-RV projects, eating away at the canopy stuff one bite at a time. The day started by jumping in to dangerous waters: drilling the holes in the rear window.  One hole was drilled at a time, then deburred from the inside, and a cleco inserted–from the inside out, so that the spreading “nibs” on the cleco wouldn’t be putting force on the plexi…rather, the large diameter body of the cleco would be holding the plexi out against the skin.  While it was clecoed, it was marked for the final trim on the forward edge, as well.  Off it came to finish the holes–30 holes, countersinks, and step drill enlargements later, plus final trim of the forward edge, there were still no cracks in the plexi!  It was reattached and held in place with a few screws for fitting of the main canopy.

Marking and trimming of the main canopy was easy enough…by the end of the day, the canopy & rear window trimming was finished.  All that’s left is to do some block sanding on the aft edge of the canopy to even up the line and provide the necessary clearance gap.  A few on-off cycles were required to get everything fitting nicely, including the lower side trims and the little part where the plexi goes under the “ears” of the canopy skin.

Sent an email checking on the shipment status of the SikaFlex supplies.  In other news, my latest order from SteinAir showed up today–the highlights were air vents and map lights, along with the usual wires, connectors, and the like.  I couldn’t resist, and I drilled my overhead panel for the lights, switches, and dimmer knob.  Looks good, I think, and seems like it will work well.  I also put some zip-tie bases up the rear channel of the flap housing, which will hold wires for the flap motor, position sensor, baggage lights, and phone/mic jacks (and perhaps other things, too…).

I decided to put the headset jacks at the aft end of the armrest, in the vertical bulkheads, rather than in the roll bar brace — it seemed like a better place after reading several threads, and thinking about the loading/unloading of baggage, and the possibility of hitting the plugs, or having to remove them each time a suitcase needed to go in or out.  Since the plane will usually have the same people in the seats, the headsets in this position shouldn’t need to be unplugged very often.  It also leaves open the option of having a place (the armrest behind the seat) to hold an ANR box, should one or us end up with a headset that has one…I’ve never liked to dangle boxes from connectors, so this fits with that well.  In any event, I drilled the headset jacks and temporarily fit them in place with the isolation washers.  I’ll need to look at my headset and see what the orientation of the plugs is to get the correct jack position (mic/phone inboard/outboard), for the volume control box to be right-side-up.

Installed various tie-wrap bases for the tailcone wiring runs, and pulled the aft nav/strobe, pitch trim, pitch servo, VOR and transponder antenna cables into the tailcone.  Installed standoffs for the static line in the tailcone and secured the line, checking for clearance with the harness anchor bracket.  Installed the ELT mounting bracket.

Worked on fitting the canopy frame by clecoing the skin to the forward frame weldment and fitting to the fuselage.  After several on-off cycles and adjustments, it was fitting pretty well, so the splice plate was drilled to the forward bows.  Removed the skin and cleaned out the chips, then re-clecoed and checked the fit on the fuselage.  Fits the same, with the usual slight gaps at the left & right front sides, that require spacers under the front skin.  An initial check of where the hinge holes will fall shows that the holes are almost dead center in the hinge goosenecks…I’m pleased with that, though I do need to fabricate spacers to go between the goosenecks and the forward bows (that distance is set by the holes in the skin, and mine has a gap…no biggie, it looks like a piece of .063 and .040 will fill it nicely.

The issue at the moment with the canopy frame is that, for the outboard three holes of each side’s aft tube, the skin does not sit down to the tube…there’s quite a gap.  I’ll have to read up on what others have done here, whether make spacers, omit these holes, or what.  Also trying to figure out when the canopy stiffener kit should be fit, as there is no mention of it that I can find in the manual.

First things first, a plumbing tweak.  I was stumbling around on VAF last night on a completely unrelated topic when I came across a thread about fuel vent routing.  Those lines that I was so happy with had to be adjusted, because I ran them to the top of the bulkhead at a 90-degree angle, which would later interfere with the mouting of the subpanel.  This post has a picture which illustrates the issue.  Not a big deal, I just removed the adel clamps on the aft vertical run, undid the bottom fitting, bent the correct angles at the top, then trimmed the lower portion of the line and re-flared.  The plumbing is really done now…I think.

Nextly, back to work on the aft end of the plane.  I finished drilling up the holes in the horizontal stab, then attached the elevators and fitted the counterweights.  The right elevator is a bit nose-heavy, while the left is almost dead-on balanced.  Supposedly, nose-heavy is the way you want to be before paint, since there is more surface area (thus more added paint weight) aft of the pivot point.  Clamped the counterbalances to the stabilizer in preparation for fitting the pushrod.

Since the pushrod needs to be fabricated and primed, I took a diversion next to install the control column.  This meant attaching the pivot brackets to the spar, then building the control column on top of them.  This task is complicated by all the various washers to be installed, and I had to fiddle with a few different combinations in order to get it to move smoothly.  After a final test fit and adjustment (these were initially fit during assembly of the center section bulkhead), I greased up the brass bushings and bolted the sticks in place.  I should be able to install the grips and wiring without removing them (crimp the pins, slide the wires down, then insert the pins in the connector), but I’m leaving the cotter pins out for now just in case….it’s s tight space and I’d rather only fiddle with cotter pins in there once.

First order of business tonight was to attend to the misplaced fuel lines.  It turned out okay to pull them out from the inside, then re-run them in the correct holes.  Due to the differing geometry of the bends, the left line was re-usable, but the right line, when re-run and bent to mate with the selector, was too short — only about 2″ protruding from the fuselage, instead of the 4″ I was aiming for.  (Notes from other builders indicate that the necessary length is around 2 5/8″.)  So, out came the right one and I re-made a fresh line, using the coil of tubing I had set aside with the fuel pump output bend in it.  I cut it to the approximate length I needed, using the removed line as a guide, and it looks like there will be enough tube left to complete the run to the firewall, which is good news.  Crisis averted.

Next on the list was the brakes.  I finished fabricating the parking brake valve bracket, drilled the holes for the valve mounting bolts, drilled for nuplates, match-drilled the firewall (nutplates will go on the forward side of the firewall so that insertion and removal of the valve won’t be a two-man job, especially should it need to be removed for service).  I set this up to have the control cable go off to the left, as I liked what I saw in some panel photos today that had the parking brake control tucked under the panel and forward, along the left side of the cockpit.  It makes sense to keep it off the panel, being a not-often-used control.

Test fit of the brake valve looked good, so I installed the appropriate fittings and went to work on the brake lines.  Bending the lines around the angles at the firewall took some conjuring, but it wasn’t all that bad. Once the bottom tube (which will be the left brake) was made, the top one was essentially the same, with adjustment in the bend radii as needed so the tubes would essentially parallel each other.  I bent the front half of the tube, then estimated the length for the run along the spar, cut, bent the transition, and ran the tube out to the gear tower.  Repeat for the right side.  Installed the bulkhead fittings in the gear towers, as well, so that end of the lines could be torqued in place.  The valve end of the lines will wait until later, since the valve bracket still needs to be primed and riveted.

Well, maybe the ease of installing those fuel lines yesterday was a sign that something was amiss.  I realized after looking at some pictures on other web sites that I ran the lines through the largest (top) bushing, thinking biggest tube = biggest bushing.  Not so…the largest bushing is for the wiring bundle.

Not a problem, right?  Just get some 3/8″ vinyl tubing, slit it lengthwise, and slide it over the tube into the bushing to take up the space and provide cushion, then pull the bottom bushing, drill out the hole, and install another large bushing.  Not so fast, according to a thread on VAF:

It is only Kosher if you don’t run any wires under it. Should you have a leak, the fuel could drip on the wires and that may not be a good thing.

Any Tech Advisor worth his salt would ask you to move the fuel lines to the bottom holes.

[...]

….don’t run the fuel lines above the wiring….it’s not acceptable aviation practice (ie very dangerous).

[...]

When in doubt you can always refer to the bible (AC43.13). Section 8 says: “Where practical, route wires and cables above fluid lines”.

Vans RV7 DWG 11 also specifically notes that the bottom snap bushing in the relevant cover support ribs (F-783B and F-783B) is an SB500-6 for the 3/8″ fuel line. The top snap bushings are an SB625-7 for the electrical wires.

Sigh.  Looks like I’ll be ordering another spool of 3/8″ tubing.  I almost put one on the last order…wish I had, it would have been a guarantee that the first time would go perfectly and I’d never need to touch the extra.  I don’t know that I’ll be able to pull these out intact and have them be the correct length, etc.

Finally conquered the selector-to-filter line, after the umpteenth iteration.  I ended up not using the swivel elbow on the filter inlet, because the short tube was impossible to bend and have room to slide the sleeves on and flare.  (The Rolo-flare, plus the sleeve, requires about 1 1/4″ of straight tube at the end to accomplish the task.)  Once that was done and in place, I mocked up the required bend to get the pump outlet routed down under the tunnel cover, with a piece of scrap, then replicated that in the end of a long piece of tubing…that’ll sit on the shelf for awhile until I determine where the firewall penetration fitting will be, at which time it will be run up there.

With the selector and pump solidly in hand, I moved on to the tank-to-selector plumbing.  These are the lines everyone talks about, that they’re so difficult, and the latest fad has been to use flex hose instead.  I actually found them rather easy, but maybe that was just relative after the three-day battle with the aforementioned connection.  I ran the spring bender through the side skin and the gear tower, then fed the tube in little by little, guiding it through the snap bushings until the end was at the fuel selector.  Bend as required, flare, done.  Repeat for the other side.  The right is slightly different than the left, as I have provisioned a tee for the AFP injection purge return line into the right tank feed line, just below the selector.

Took a moment while I had the fuselage on its side to install and torque the elevator bellcrank.  Also trimmed the aft end of the canopy decks, which I had somehow missed in the earlier trimming…this removes the bit of the piece that would otherwise cover up the outboard portion of the canopy latch hole in the gusset plate below.  Easy with the Dremel tool and a cutoff wheel, followed up by some small files & scotchbrite.

Next was fitting the center tunnel cover…this wasn’t as bad of a task as I had been fearing.  The firewall recess was clecoed in place, then the tunnel cover set in place and measured for the proper spacing from the bottom skin.  #30 holes were drilled at four locations on each side, then enlarged to final size, and the holes were drilled into the firewall recess.  Cover was then removed and split in half, to allow the front portion to be installed separately from the aft portion.  This is necessary because the fuel line goes under midway up, forward of the boost pump, rather than under the selector.  All pieces deburred, nutplates drilled and installed, heater box louvers bent, then checked for fit again with all the rest of the pieces, boost pump, and tubing…very happy to see that the selector-filter tubing still fit correctly.  Removed covers and set aside for later.

What’s next…brakes!  I have the new Matco parking brake valve, which I plan to install in the same place that the bracket on the firewall is (using the valve as the transition point from flex lines to solid lines) — so the first step was to drill off the existing bracket.  Next, I need to fabricate a bracket that has a provision for fixing the control cable in place.  I drew out, cut, and bent one that holds the valve horizontally (so the lines enter left and exit right), with the control cable coming from the right of the valve.  Not sure that’s where I want the control, so I’ll be looking at what others have done to mount this thing.