Avionics and Wiring

October 22, 2020 – I realized when I looked at my time log how long it’s been since I posted an update, so here goes…

Com Harness

I finished the connectors and put the harness in place. I’m trying my damnedest to not have a rats nest here. Once everything is clamped in place and tied back, it’ll be OK. This is what happens when a sheet metal guy handles wires.

I did the headset and mic jacks. I made some a long time ago, but I didn’t have wires for PTT in there, so I took mine out and used the new ones.

I also installed the antennas.

Tailcone Wiring

Well, I call it the tailcone because once I get in there, I may as well be all the way back there.

I assembled the harness for the autopilot pitch servo. Power, ground and a yellow wire for AP disconnect go up front. The rest go into the Skyview network.

Since I have limited space for wires to go up the tunnel between the seats, I bought a hub to put in the tailcone and I ran a 15-foot Skyview network cable to the front.

I made a bracket where the transponder attaches to the center beam in the fuselage.

Air Temperature Probe

I installed the OAT probe in the fuselage under the left horizontal stab. I ran the wires up through tiny grommets I had and they go straight to the ADHRS.

Panel

For a long time I had the “life-size” Dynon templates taped to the panel on my table and I was playing around with them trying to find the best locations. When I was ready to make a decision, I found out that those templates were about 1/4″ small. That made a big difference in what I was going to do. So I did some rearranging.

In the above pictures I have the two coms with the intercom panel above them. I wasn’t sure I liked that, so I redrew that stack with the intercom underneath. Much better.

I decided to do the cutting myself. Lots of filing…

It appears that except for the intercom panel, all the Dynon panel items have the same cutouts. Nice idea…

After those center items, I did the cutouts for the screens.

Here’s the panel in the airplane:

I still have to do the other small items in the panel, which I just ordered.

I’m just going on, routing wires and terminating them as needed. One wire at a time…

Time: 42:00

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Vinyl?

June 25, 2020 – I experimented with vinyl.

I’ve been intrigued by the use of vinyl instead of paint on the airplane. I decided to give it a try.

I ordered a 3×5 piece of 3M 2080 Gloss White. I decided to try it on the right elevator.

The first thing I wanted to do is to paint the leading edge row of rivets. This turned out to be a waste of time because you can’t EVEN see these rivets when the elevator is installed.

I cut a piece of vinyl large enough to cover the top of the elevator. It’s all pretty straight-forward, after watching a few dozen You-Tube videos.

Here’s the final product, for now.

Lessons learned:

  • Two people.
  • Cut a much bigger piece of vinyl so you can grab it an maneuver and pull it into position.

There are a couple of hard wrinkles, that will make it necessary to redo this. I kind of wish I’d started with the bottom of the elevator. I did the top because of how I’d wrap the trailing edge.

The other part I have to figure out is how to do tight curves like the tips.

Time: 1:40

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Rudder Lower Fairing

June 25, 2020 – I worked on the lower rudder fairing some more.

The leading edge of this thing has been giving me fits.

Even when I built up the leading edge, by the time I sanded it smooth, the material in front of the rudder horns was paper thin.

So I bent the tabs of the rudder in just a bit to make some room, then I mixed some more resin with flox and caked it inside the fairing at that point. With the fairing in place, it just fills the gap. When it was set up, I removed it all and sanded to smooth it. It fits much better now.

Time to move on. I hate fiberglass.

Time: 4:20

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Drilled Elevator Horns

June 25, 2020 – Well, the third time’s the charm. I drilled the elevator horns and they are actually aligned!

I was able to get a rod end for the elevator pushrod with a 1/4″ bore, so I went with doing 1/4″ holes in the elevator horns. My friend on the airport welded one of the holes closed (again).

Since I wasn’t having as much success with my drill bushings, I found a wire brush that had a hole drilled through the handle. The handle was exactly 1″ wide, which is the space between the horns, and the handle fit in between very snugly. So I pressed a .248″ bushing into the handle and cut the head off.

I nested a smaller drill bushing in that to get the hole started, then I ran a .248″ reamer through there.

Finally!

Time: 2:00

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Elevators and Rudder continued…

May 29, 2020 – A simple plan has turned into trouble for me.

Elevators

I installed the elevators and got ready to drill the control horns.

I clamped the tips in place and in line with the stabilizers.

The left horn is farther aft, so I piloted a hole in that one per the drawings.

I was happily drilling away using drill bushings and reamers. Didn’t pay attention that the hole is supposed to be 3/16″. I made nice 1/4″ holes.

The problem is that the elevators didn’t line up afterwards.

OK. So I took them back off and a friend at the airport welded the holes closed.

I cleaned them up and hung the elevators to do it again.

I’m a moron. I finished the holes with a reamer that is the equivalent of a #9 drill. Now the holes are sloppy, and still not perfectly lined up…

Time to walk away and do other things. I did order the same rod end that goes on the elevator control rod, but with a 1/4″ bore on it. If I can get these straight, I’ll use a -4 bolt instead.

Rudder

I got a new internal rudder stop from Flyboys, since I over-adjusted the last one. This one came out much better.

Time: 7:35

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Tail Fairing

May 29, 2020 – I’m finally satisfied with my tail fairing.

Here’s the original stock tail fairing with the “ears” that go down behind the horizontals. I’ve had a lot of trouble with this partially because I tore the left side and repaired it. (This is actually a picture from when I back-drilled holes into my new solution, but more on that later…)

There’s an RV-14 in my hangar that I walk by every day. I looked at the tail fairings on it, and I thought I’d try to reproduce them. I bought a 2×4 sheet of .025 T3 from Spruce, and a piece of poster board.

I used the fairings and the inspection panel as a unit, and roughly traced the outline onto the poster board.

I cut this out and tried to secure it in place on one side. As long as it was close…I knew I’d cut the aluminum large and final-fit.

I back-drilled the holes from the original metal lower fairing, and screwed the new piece in place. Then I put the fiberglass fairing over the top and back-drilled the remaining holes. That’s the first picture I showed you:

I also marked all the trim lines to have the edges all aligned and clean.

The inspection panels will be under the new fairing. If I need to remove one of these panels, I just remove the screws on the inspection panel and slide it out from under the fairing.

The last step was to joggle the fairing because the fairing does not sit flat against the fuselage skin. This is on the RV-14 fairing as well. I drew bend lines and put in gentle bends on a small brake in the hangar.

Once I did the left side I stopped for the day. I came back the next morning and did the right side. The first one took 3 hours; the next one only took about an hour to make.

The last thing I had to do was cut the “ears” off the fiberglass fairing. There’s a screw hole right in line with the trailing edge of the stabilizer, so I drew an angled line swept aft. That gives it a more sleek look.

Here’s the metal fairing in place (before final trimming). I’m really proud of this:

Time: 7:10

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Tail Wiring

May 8, 2020 – I ran the wiring from the tail forward towards the cabin.

I have the wire bundles for the taillight and for elevator trim. Trying to figure out the cleanest and safest route for the wires…

Here’s what I started with:

I didn’t like the lack of support going into the tailcone. So I drilled a hole in that upper bulkhead and placed a snap bushing there.

I realized I was going to need a path all the way up at least to the wing spar. I was also going to have to run coax from the transponder and ADSB antennas that way, and I couldn’t figure out how I was going to do that. My seat pans are riveted down, so I didn’t know if there was a way to run wires forward under those. The bulkheads are solid forward and aft. So I took a look at the drawings for those bulkheads.

Well, I realized that some holes were hiding from me. I already had holes and snap bushings in the bulkhead between the seat pans at the flap torque tube.

That was half of the problem…how do I get the wires past the elevator torque tube at the baggage bulkhead?

I looked again at the drawing for that bulkhead. Wait a minute…there can be holes there. I don’t really know why I never drilled them.

So okay…I have to drill two 5/8″ holes in there with limited access, without hitting the rivets or damaging any structure.

I carefully drilled two #40 holes, and then took them up to 1/2″ with a small unibit. How to get to 5/8″? A friend had welded a rod onto a large unibit. So I could chuck it into my 3/8 drill and get it down in there.

Here’s the result…

Deburring was almost as much fun as drilling these holes…. Just have to do some paint touch-up too.

And here’s the final result:

I installed a clamp on a bulkhead to hold the wires clear of the elevator pushrod:

I finished this by lunchtime that day, but with the crawling around back in the tailcone, I was ready to go home and go back to bed…

Time: 8:30

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Elevator Trim Wiring

May 8, 2020 – I connected the elevator trim servo to its wire bundle.

To get a connector in the tailcone where it can be accessed, I cut about a foot of the wire bundle and spliced it to the servo wires. Those wires are so short, they stay buried inside the elevator, so they needed to be extended.

One big issue I ran into was that I didn’t have wire strippers small enough to handle 26 gauge wire. I have an Ideal stripper, and I guess I wasn’t aware that the blades could be changed. I found a set on Amazon that was a whole lot cheaper than buying a new stripper. This range of wire sizes will make more sense for the work I have coming up.

So here’s the wire I have running from the servo out of the elevator. I’m just running it in the open space of the elevator leading edge. I installed a 6-wire molex connector I got from Stein.

The disconnect will lie in the space under the vertical stabilizer. Here’s the connection with the elevator on:

Time: 8:30

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Tail Light

May 8, 2020 – I finished the wiring for the taillight on the rudder.

I installed the molex connector (provided by AeroLEDs) to the pigtails on the light.

I drilled the hole in the vertical spar for the wire to pass through. After a lot of thought and soul-searching about how to route this wiring, I looked on the RV7 Plans CD I got from Van’s. I found OP-56 which covers tail lighting. So I drilled the hole as dictated by this drawing. It goes in the upper half of the lower rudder hinge bracket. The local ground here uses one of the mount bolts for the tailwheel bracket.

So I installed the other half of the molex connector on my shielded wire bundle, and put a piece of expandable wrap on the wire where it passes through the spar.

I doubled up the ground wires. One is for the light itself and the other is for the shield ground for the wire bundle. So I will have two wires connected to the local ground; this pigtail from the molex and the separate chassis ground wire from where the light attaches in the fairing.

Here’s where the wires will exit from the lower rudder fairing.

I have since enlarged that hole so the molex will fit through it. May never have to come apart, but being a mechanic, I’m always trying to think about maintenance, unlike engineers, who just design it to put it together, and solve the maintenance problem later.

I put power to the light to try it out. Wow! I couldn’t see for 15 minutes afterwards! Strobe and position light work great.

Time: 5:00

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Continued Tail Fairings

May 8, 2020 – I continued on all the fairings for the tail.

Fill and sand…fill and sand…fill and sand…

At this point, I’m getting to where I’m happy enough with the fairings that it will fly. They’re surely not paint ready, but I don’t have the patience nor the expertise right now to get them absolutely perfect.

Here’s the tail wrap-around fairing:

I installed the nutplates for the fairing, until I ran out… I did order nutplate jigs from the Yard Store for #6 nutplates. I can’t stand doing nutplate holes from a nutplate. Way too much error. More nutplates on the way from Spruce.

I did the elevator tips. They don’t require any major fitting.

I also installed the nutplates for the side inspection panels in the tailcone. I’m working toward installing the rudder and elevators permanently, so I’m addressing anything back there where they might get in the way. Here’s a nice shot showing the inside AND the outside:

Time: 20:20

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Continued Tail Fairings

April 10, 2020 – I continued with the fairing for the vertical stabilizer.

I had to force the fairing into position, then I drilled the pilot holes for the screws. The right side does not pull down as far in the back, so I have to extend that part just a little bit.

I’ve also been working on the upper fairing as well as the tips for the elevators. No current pictures of those.

Time: 3:05

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Continued Tail Fairings

April 4, 2020 – I continued work on the fairings for the tail.

I decided to enclose the elevator tips and make the cap wrap around the lead weight in the front. So I taped off the weights to keep the resin from sticking, and I wrapped cloth around the front. I also taped along the edge and filled there to smooth the transition between the elevator skins and the fairings.

Well, when I went to sand the ends, it was too thin. I also couldn’t remove the fairings…  🙁

So I decided to install them in place, and just use filler to fair out around the weights. Haven’t gotten to sand them yet. Hopefully this will work.

I moved on to the top of the vertical. I had previously made a foam plug to close the open end that faces the rudder. I hung the rudder back in place, and had to remove some material from the small vertical fairing for clearance. There’s a nice gap there now. I just have to seal the foam where material was removed, then fill the front of the rudder where the weight and the rudder skin are mismatched.

Then I moved to the fairing that wraps around the vertical and the horizontal stabs. I looked at the lower fairings, just flat pieces of aluminum that close the space under the horizontals. This is screwed in place into the longeron. So I removed the appropriate rivets, drilled up to #36, and tapped the holes for 6-32 screws. I also trimmed the tops of the fairings to give space for the rubber seal that will go there.

The top fairing fits OK. I wanted to get the front parts of this fairing fairly tight against the leading edges of the horizontal stabs, so the fairing twists a little bit when forced into that position. I’m backing off and thinking about how best to deal with this.

Time: 12:40

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Tail Fairings

March 12, 2020 – I started working on the fairings for the tail surfaces.

The fairing for the top of the rudder is probably the easiest fiberglass piece on the airplane. I just had to cut the fairing to clear the wedge in the trailing edge of the rudder. The rest was easy.

I then hung the rudder to check the clearance and position of the vertical stab top fairing.

Here’s the fairing in position.

Once I got the pilot holes drilled, I removed the fairing and glassed in a plug to close the backside.

I moved on to the elevator tip fairings. More or less the same as the rudder fairing. I cut slots for the lead counterweights, and fit and drilled the fairings.

Time: 6:00

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Continued Work on Rudder Lower Fairing

March 6, 2020 – I continued the lower fairing on the rudder to prepare for the installation of the tail light.

I drilled the new screw holes to mount the fairing. The holes you see in this picture are the old ones, and they are filled with resin, so no worries about edge distance.

I installed the nutplates in the rudder.

I installed the chassis ground for the light. Not a lot of room in there. Hopefully this will be adequate. I removed one of the pop rivets and put a screw in its place, with a terminal on the inside.

Here’s a test fit of the light.

Time: 7:05

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Continued Lower Rudder Fairing

February 6, 2020 – I stated on my previous post about the fairing that I had a couple of issues with its fit.

  • The light contour and the attach plate are bigger than the molded area the light attaches to. I’ll just build that area up to make a smooth transition.

  • I figured out that the fairing is now not vertically aligned with the rudder. I sighted up along the rudder trailing edge, and the fairing doglegs off to one side. Hopefully cutting the offending side at the screw holes will bring it back into alignment…

First, the misalignment.

Here’s a picture, best I could get, of the misalignment:

It’s kind of hard to tell, but it’s there. I cut a bit of material off the top on the right side, to hopefully pull the fairing towards the centerline when screws are installed. I filled the existing pilot holes for the screws, and I’ll redrill new holes when everything else is set.

Then I started working on fairing the light a bit better. I mixed a batch of resin and flox, and slathered it around the base plate for the light, as well as gluing the plate to the fairing. After it cured, the first sanding went pretty well. I just have to do the usual fill and sand…fill and sand… I also installed four pop rivets in the base plate to help to mechanically secure it.

Time: 3:15

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Started Rudder Lower Fairing

February 2, 2020 – I started the lower fairing for the rudder that will also hold the tail strobe.

The fairing that comes from Vans was two pieces that they put together. They provide scribe lines on the part that are suggested cut lines. I know from experience that these lines are just guidelines, and that you should do your own fitting.

The first consideration is that the fairing needs to clear the tailwheel spring. I cut about 3/8″ off the top to give the fairing a 1/4″ clearance above the spring. You also have to make cuts to clear the control arm for the rudder.

I also needed to cut the front of the fairing to give clearance for access to the lower hinge bolt.

Then I trimmed the top to allow the fairing to fit along the lower edges of the rudder, where the fairing will attach.

I drilled screw holes through the fairing and the attach flange on the rudder. I’m going to use #6 screws and nutplates, since I want the fairing to be removable for the light.

This all sounds pretty easy, doesn’t it?

Well, when I got the fairing fitted, I found that the trailing edge of the fairing was mismatched with the trailing edge of the rudder by about 1/4″.

I figured the easiect way to fix this would be to split the trailing edge of the fairing, remove material from the pulled side, then resin the fairing back together.

It took two iterations of this process to get the fairing aligned.

In the meantime, I made an adapter plate to attach the light to the fairing. The plate is 1/8″ aluminum, made to match the contours of the light. I drilled and tapped the screw holes to directly attach the light. I had to chamfer the edge of the hole where it meets the back side of the light housing.

Still not done. Two problems…

  • The light contour and the attach plate are bigger than the molded area the light attaches to. I’ll just build that area up to make a smooth transition.
  • I figured out that the fairing is now not vertically aligned with the rudder. I sighted up along the rudder trailing edge, and the fairing doglegs off to one side. Hopefully cutting the offending side at the screw holes will bring it back into alignment…

Time: 9:25

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