Joshua's RV-9A Project

Spent a bit of time fussing with the control cables again.  I didn’t come up with a bracket solution that satisfied me, because the too-short mixture cable would need it’s bracket a couple inches closer to the firewall than the throttle.  The extender wouldn’t solve that, just make it reach the lever.  So, I guess I’ll order a longer custom cable, wait for it, and get it in right; then sell the short one to someone who can use it.  Also, more aluminum angle to redo the bracketry.

Cut the side hinges and hinge shims that will hold the lower cowling, and drilled them to the firewall.  Marked and cut the slot in the cowling for the gear leg.  Cleaned up the fiberglass on the backside of the nose flanges and refit the cowls together.  Clecoed the top cowl back on the plane, then put the bottom cowl on via the two clecoes in the nose, and a cargo strap under the rear portion.  The fuselage end seems like it will fit decently, but the nose doesn’t hold alignment with the spinner backplate — the gap at the top right side is 1/4″, and the lower left is 1/2″.  This might close up a bit with the rest of the fitting, but it looks like a load of filler will be required.  (Apparently this is not uncommon.)

You know you haven’t done much work on the plane when the “remember me” on the build log has expired and you have to go find your password.  Busy times at work, church, and freelancing.  Should be done in another 4 weeks, then summer can begin.

Worked on fitting the cowling halves together for a bit tonight.  Cleaned up the flanges around the center hole, and got them fitting decent.  Drilled a #30 hole in either side to maintain alignment; will be filled later.  Need to do some reading up on cutting the gear leg notch, and the filler plates that go in said notch.

Made up a long sanding block with a 2′ length of 1×3, and a piece of sanding paper cut in half lengthwise.  A little drywall bead adhesive spray, and presto.  Worked on the fit of the top cowl with a bunch of on-off cycles.  I found that I needed to trim back the camloc strips at the lower sides, because they were hitting the thicker honeycomb-core portion of the canopy.  With everything fitting correctly, and the canopy shimmed at the front with chunks of an old Mouser catalog, I carefully drilled the holes to #30 along the camloc strip, starting in the center and working down.  It seems to have gone alright, the positioning looks fine, even after the catalog was removed.  I intentionally left as little gap at the rear as possible, and it’s a bit uneven in spots, so ‘ll have to carefully sand it to the recommended 1/16″ paint gap.  It’s surprising, actually, how solid the cowling is when it’s clecoed on all around.

A bit of FWF work: installed adel clamps for the oil and manifold pressure lines, and looked at possible clamping locations for the fuel line to the spider.

Finished the preliminary work on the camloc strips for the upper cowling: trimming to length, completed drilling to the firewall, transferred the layout lines for the camlocs, and drilled for the camlocs with the first template (3x #30 holes).  Clecoed the strips back on, and set the upper canopy in place.  Marked a rough trim line that just clears the clecos, and cut with the oscillating saw.  More fitting will be required, of course.

Stopped by the airport while out and about today and picked up a possible lead on a hangar space.

Spent a bit of time messing with the cable throws on the throttle and mixture, then moved on to the beginning of the cowling tasks. For some reason, I’d been dreading making up these camloc strips, but it wasn’t that bad. I took off the top skin and used the forward edge of it as a template to get the necessary curve. I’ll have three pieces: one pretty straight section in the top center, then one additional section on each side to run to the bottom of the top cowl. The pieces have a hockey-stick shape when laid flat, but they fit nicely to the curve of the firewall, and the angle is correct for the slanted portion at the top. Turned out well, so I drilled the side segments in place. Ran out of time to drill the top center piece, but it’s ready. Worked on measuring off the layout for the camlocs, to see where the divisions of the strips could be without interfering, and marked the strips for cutting.  At the spacing I ended up with (3 14/32″), I’ll have 16 fasteners on the top cowl.

Did a couple more odds and ends that needed doing, including some fun contortions to work in the baggage and tailcone areas:

• Installed the DB-9 connector for the autopilot pitch servo
• Installed new nutserts to secure the seat heater relays in their new positions
• Torque seal on the fuel flow transducer bolts
• Installed nutplates for the aux alternator relay and capacitor
• Placed the N-number placard on the panel

Also refit the canopy and forward top skin in order to look at a few things up there:

• Attached wire to and nstalled the strip of LED’s that will be the panel floodlights.  Temporarily connected to the switch to test; still need to run those wires for real and put a connector behind the panel.
• Checked again for clearance between the outer top corner of the EFIS and the panel reinforcement; looks like it should be fine, as planned.
• Checked for catching of the canopy skin when opening; looks ok after filing off a bit more from the forward edge.
• Found where the canopy frame is rubbing on the side seal support angles (which weren’t yet installed when the canopy was previously fit).  Those will need to be filed down for clearance.

More wrapup of loose ends in the cabin area, mostly dealing with the last of the electrical:

• Installed the DB-37 connector shell and hood for the ADS-B, and tied up that bundle.
• Installed the hood on the ARINC module connector.
• Soldered the 3.5mm jack on the ADS-B maintenance port connector, enlarged a tooling hole in the subpanel, and installed the jack there.
• Fabricated engine ground cables and installed between the firewall ground buss and the engine case.
• Measured for throttle and mixture control cables.
• Cut and installed the ducting between the vent scoops and the panel vents.  (Need to get some screen mesh to put on the vent scoop end to prevent ingress of bugs.)
• Removed the parking brake cable from its mount, so that the mount could be removed and painted.  Realized that the ball bearing fell out of the cable mechanism; spent some time searching for it in vain.  (Hint to similarly troubled souls: ACS sells replacement balls for $2 apiece; a bag of 50 is under $5 at McMaster, and then you can lose it 49 more times.)
• Swapped out all the screws on DB connectors for thumbscrews…much easier to work with, especially upside down under the panel.
• Installed a snap bushing in the left subpanel rib for the pitot and AOA lines to pass through.  Ran those lines up the left vertical FW stiffener and tied in place.
• Tidied and tied up the bundles of wire in the tunnel.
• Cut pieces of vinyl tubing to slip over the tubing in the tunnel for anti-chafing at tiedown points.  With much contortion, tied up the fuel and brake lines in the tunnel.  Still a couple to do, and one tiewrap base where the glue is obstructing the hole; it may be possible to open it up with some safety wire.

The day’s other task was attempting a redo of the nosewheel bearing.  When I installed the wheel before hanging the engine, I noted that the rotation was quite stiff.  I have the Matco axle which was supposedly designed in part to alleviate that problem.  It’s very stiff…one theory was that I didn’t manage to properly grease the bearings (they are tricky to hand-pack with the molded rubber seal).  So I bought a bearing packer cup, which did a fine job of packing it; grease squeezes out under the seal.  Re-installed, and no change.  If I tighten down the ring on the axle that’s supposed to set the preload (the instructions say to tighten it until the bearing face does not rotate with the wheel), the wheel requires what seems to me to be a lot of force to rotate.  Given the discussion around the nosewheel issues, this doesn’t seem right.  The bearing cones feel fine on inspection, too.  Anyone out there with experience installing the Matco axle that can confirm or point out where I went wrong?  For now, put it back together, knowing at least that it is well-lubricated.

Before the engine could go on, there were a couple remaining items to take care of.  First, the nose gear had to be installed, and the wheel bearings greased.  I’ve packed bearings before, but these were difficult because they have a rubber seal on one side of the bearing, so the usual “pack it in ’till it comes out the other side” didn’t work out.  I packed it in as well as I could; the glob in my hand kept getting smaller, so it must have gone somewhere, but I’m not sure it was done perfectly, so I may revisit this wheel when I repack the mains prior to flight.  I also looked at the preload adjustment on the Matco axle; you’re supposed to tighten the preload ring until the bearings remain stationary to the axle while the wheel rotates.  I was able to get them to not rotate, but the wheel is very stiff…need to do more reading on this.

Item number two was to move the oil pressure fitting on the engine from the side port to the rear port.  I removed the fitting and the plug, and swapped them, installing the plug with EZ turn to the specified torque (which involved tracking down a copy of the Lycoming torque specs in Lycoming  publication SSP-1776).  The pressure fitting is just finger tight for the moment, until I determine if it ought to be a straight fitting instead (and if so, make one with a restrictor).  While I was monkeying with the engine, I also pre-installed the 90* fitting with the pressure tap on the fuel pump outlet.

With all that done, I took another look through my pre-engine hang list, and decided it was time.  I followed the “Illustrated Guide to Engine Hanging” and the procedure was pretty straightforward.  The trickiest part was the upper left bolt, as the nut is close enough to the pushrod tube that a box-end wrench gets trapped by the bolt when fully tightened, and the hole in the engine case is such that a box-end can’t get on the nut well.  I ground down a cheap box-end wrench so it was thinner along one edge, which let me remove it after the bolt was torqued.  Getting the cotter pins in was fun as well, and required some attention during the torquing process to see that the holes ended up in an accessible orientation.  In the end, no problems with the hang, and it’s looking good.

Once the engine was on, I couldn’t resist pulling out the fuel servo and test-fitting it. The AFP kit includes a nice anodized bracket/transition piece which fits between the servo and the sump, however, it is rather thick, and with it in place, the studs on the sump aren’t long enough to allow for the washer, lock washer, and nut.  In fact, they don’t even protrude through a single washer and nut.  Without the spacer in place, the throttle linkage hits the bottom of the sump, so clearly it needs to be there, and it also provides a mounting location for the control cable brackets.  I’ll have to look into the length issue.  Also need to look into how the airbox is intended to fit onto the servo; the parts are all there, but it’s not immediately obvious which way they’re all intended to go.  Lastly, I moved the throttle, mixture, and purge valve levers to the approximate locations they’ll need to be for the control cable attachments.

(Engine hang at ~1110 hours.)

More items from the pre-engine-hanging punch list tonight…

Installed the protection diode on the master contactor.  Need to order another diode for the starter contactor.

Installed the right-hand wiring passthru in the firewall, pretty much in a mirror-image location of the left one.  I found a number of builders who have put them here and said it worked well.  Their photos showed good wiring routes for everything, and it will be an ideal position for feeding the main buss wire into the Vertical Power box.  It also leaves open some real estate on the bottom of the firewall for the possibility of putting a heater box there.

Put the engine mount in place and snugged down the bolts to hold it.  Put the nose gear in and temporarily placed the bolt at the top.  I’m wondering if it would be a good idea to upgrade this to a close-tolerance bolt; I know some have tried taper pins but had a heck of a time reaming the tapered hole in the hard steel leg.

Decided to finish off the main gear legs, so hoisted the fuselage up one side at a time to adjust and drill the axle nuts for cotter pins.  The engine hoist and a double cargo strap to the gear tower worked nicely to get the wheel off the ground.  Since the gear-leg bolts are not yet torqued, it was easy to drill the top side, then pull the leg to drill the bottom hole.  After marking each hole with a drill bit, I removed the nut and ground a depression in the threads with a burr in the Dremel tool, then replaced the nut and drilled the hole.  Found this method on the forums, and it worked well to keep the axle threads from splitting and tearing up the nut threads.

For the gear, I’m using the grease recommended by the maker of the main wheels, Mobil Aviation SHC 100, a non-clay-based synthetic grease.  The smallest quantity I could find to buy was the 4.4-lb can…that’s a lot of grease, and it’s spendy stuff too.  I’m using this because the main wheels came already packed with it, and the nose wheel isn’t packed with anything; may as well use the same stuff all around.

Still to do before engine hang: seal and install the firewall recess (which will involve removing the top skin), seal and install the wiring passthrus and brake reservoir, pack the front wheel bearings, and deal with the oil pressure fitting.  Need to look up the mix ratio for the CS1900 firewall sealant so I can mix smaller batches than the entire pint can.

Freezing rain and snow on the way — tonight’s essential task was to get the main gear under the fuselage (Allison’s car needs inside).  While this may not be the absolute best way to go — adding the gear lifts the fuselage up quite a ways, meaning any work done over the side will now require a stool — I think it’s the best choice for this project, at this point, since it should let me pretty easily move the fuse around the shop between the “working” configuration and the “parking” configuration.

So, I bolted up the brake brackets and gear legs, omitting the wheel pant brackets for now, as I’ve read they are easy to snag and break while working around the plane.  Mounted both tires to the wheels, and put them on the legs with spacers and axle nuts, then removed the sawhorse.  I was surprised at how light the tail is in this configuration — will have to remember to be careful loading stuff, including myself, into the cabin, to avoid a nose-ground interface.  A sandbag on the aft deck should take care of that issue.  I set the tailcone on a caster-base stool, and it’s easy to wheel around the shop, so I’m hoping this will help keep progress going, and a car space open.  I’ll have to rework the shop to eliminate some boxes, in order to gain enough length for the engine & mount on the front of the fuse.