Tag Archives: Empennage

Elevator Trim tab & left fiberglass tip fitting

Hours: 4

With the two main skins fitted onto the Elevator, I started looking at the trim tab and the side fiberglass tips.

First I figured out the correct orientation of the hinge that connects the Elevator and the trim tab and the right orientation of the trim tab. I temporarily clecoed them together to check that the clearances are good and it moves all fine.
Elevator trim tab temporarily mounted

Then I was searching for the brackets that go on top of the trim tab and realized that I got two different looking brackets. Since this looked off to me, I tried to squint real hard at the instruction manual to figure out which bracket is the right one. I also checked the Sling 4 instructions and asked Matthew if he had a picture of his brackets and with that figured out that I must have received one TSi and one Sling 4 bracket, so I put in a note with the factory so I can get the right bracket for my TSi.
This looked off to me - I figured out it's one TSi and one Sling 4 Trim tab bracket
Investigative work to figure out which bracket belongs

Securing the trim tab piano hinge

With that out of the way, I focused on thinking about securing the piano hinge that attaches the trim tab to the elevator. Since there is no natural stop for the pin that goes through the hinge on either side, it could happen that it becomes lose from vibration and thus could come out during flight, which would be bad. I research a bit on the topic and found this article from EAA on the use and installation of piano hinges.

One of the ways to secure the hinge is to drill a small hole through the last part of the hinge and install a safety wire. My hinge was luckily cut in a way that makes this approach very easy to achieve. I got out a small drill bit, mounted the hinge in my bench vise and drilled a hole on each side so I could run a safety wire through it.
EAA diagram to safety the hinge Hinge mounted in my bench vise to drill the hole for the safety wire Hole drilled for the safety wire Safety wire in place to test free movement while connected to the Elevator

Using the safety wire approach makes it easy to still remove it in the future, but ensures that the pin stays securely in the hinge.
Testing free movement of the trim tab with the safety wire in place

Fitting the left side fiberglass tip

For the last part of the day, I started on fitting the last part of the skin and the fiberglass tips. Since this requires moving around the tip from both sides, I moved the Elevator over onto some saw horses so I could access the bottom more easily.

First I clecoed the top skin in place and then I slowly fitted the fiberglass tip in place. In order to get the fiberglass tip to fit, I had to file a tiny bit at the back, but it was much easier than the Rudder tip fitting.

Once I had it in place, I started to hold everything tight together and started match-drilling holes into the fiberglass tip. I used liberal amounts of clecos to get a tight fit and everything looks good. Now I just need to repeat it on the other side.
Top skin clecoed in place Fiberglass tip fit in place and ready to match-drill Marking drill holes Fiberglass tip match-drilled

Elevator skin fitting

Hours: 3

First order of business for the Elevator skin was inspecting all edges and holes and there were a few edges that needed some deburring action.
Elevator skin edges needed some filing to remove the burrs

After deburring everything that needed attention, we wrapped the skins around the rib structure. Since the Elevator is a pretty big part, it was very helpful to have a second pair of hands for this.

The last thing I had to do before I can start on closing up the skin is to install the backing plate for the Trim motor inspection plate. The plans call for 1/8 rivets, but the holes were actually 3/32, so I had to first up-drill them. There’s also another small error in the plan, in that it says to rivet all 8 holes, but actually only 7 should be riveted, since the top hole is for the screw that holds the inspection plate in place.
Backing plate goes under the skin Holes are 3/32, so I needed to up-drill them to fit the 1/8 rivets Holes up-drilled and backing plate clecoed in place Quick test fit of the inspection plate

Elevator structure

Hours: 5.25

Time to finish off the Empennage and get the Elevator structure going. I received the replacement ribs that are bent just that little bit more in order to properly align with the reinforcement plates and skins and went to work to drill out the bad ribs and put in the replacements.

New ribs in place and a final picture of a few rivets that people that visited helped pull

After that, I went to work and torqued the bolts that connect the control rod and counterweight to the Elevator. There’s also a small support bracket that reinforces the center rib to spar attachment, which is a pretty tight fit, so I had to get out the manual hand riveter.
Torquing the AN bolts Bolts torqued and support plate riveted

My brother is currently visiting and is enjoying the riveting experience.
My brother enjoying the riveting experience

Once the center ribs were finished, we moved on to put the rest of the rib structure in place.Elevator rib structure finished Clecoing the ribs in place

After that I realized there’s a mistake in the plans as they instruct to rivet the edges that hold some of the side counterweights on, but there’s another small end rib that actually has to go on there as I found out after I checked the overall plan for the Elevator. Quickly drilled out the rivets and riveted on the part. A nice trick I learned from another builder for drilling out the rivets without damaging the holes they go through, is to only drill out the top of the rivet (the donut ring) and then use the center punch to push out the back of the rivet. This way you have less chance of enlarging the hole.
Error in the plan says to just rivet the endcap, but actually this part needs to be riveted onto the side End rib where it should go Holes drilled out and end rib ready to rivet

With the rib structure in place, time to work on fitting the skin.

Vertical Stabilizer skin riveting

Hours: 3.5

With the wiring finished and the Antenna fitting done, I am now finally able to close up the Vertical Stabilizer and rivet the skin.

To begin, I closed up the left side of the skin and held it in place with clecos, since this is the side where the Antenna slides through the enlarged rivet hole, while on the right side I had to create the custom notch so that I can pull the skin around the Antenna.
Left side of the Vertical Stabilizer closed up with clecos

Once that was done, I riveted on the support plate for the Antenna onto the top rib of the Vertical Stabilizer.
Riveting the Antenna support plate in place Antenna support plate riveted in place 

Now that the structure is complete, time to mount the Antenna permanently in place. Using two 20mm long M4 screws, washers and Nyloc nuts and some medium strength threadlocker I mounted the Antenna in place. Here’s the Antenna mounted in place and the wire connected to the Antenna using the BNC connector I crimped onto the wire. Antenna ready to be mounted Antenna mounted and wire connected

Riveting the skin

With all the prep work finished, I closed up the right side of the skin, made sure everything fits correctly and clecoed it in place. There are two holes on the bottom on each side that are not riveted, but instead I have to install Rivnuts in them, so I marked out those holes, so I don’t accidentally rivet them.
Vertical Stabilizer skin closed up and ready for riveting Holes where I have to install Rivnuts marked

There were two rivets that I had to shorten in order for them to fit flush near the Antenna. So I made a small template for the dept through a piece of wood and then shortened them accordingly.
Wood piece to hold the rivet in place to shorten Rivets shortened (and normal length on the left for reference)

After that, it was just a matter of pulling the many rivets on both sides of the skin to close the Vertical Stabilizer up for good.
Riveting the right side in progress Riveting the left side in progress Riveting the left side in progress Done riveting the skins of the Vertical Stabilizer

The last part was to install the two rivnuts on the bottom on each side, so after enlarging the holes using my step drill and reaming them out using my hand reamer, I got out my rivnut puller and high strength loctite and put those in place.
Holes enlarged for the rivnuts Rivnuts installed

With the Vertical Stabilizer completed, I then did a quick test fit and mounted it on top of the Fuselage and also attached the Rudder for a moment – almost looks like an airplane.Completed Vertical Stabilizer  Quick test fit of the Vertical Stabilizer and Rudder

Timelapse of building the Vertical Stabilizer

Technical Counselor visit & Vertical Stabilizer Antenna wiring

Hours: 5

This morning I had my first visit from my local EAA Chapter 84’s Technical Counselor to look over my build and give me some advice as part of EAA’s Technical Counselor program.

This was the first Sling kit for him and he was impressed by the quality of the kit, its completeness and the instruction plans. We looked over my completed parts of the Empennage and talked about wiring, avionics and things to look out for. He also gave me some good general advice and stressed the point of documenting, particularly around wiring, since many years down the line there’s nothing worse than finding a wire and not knowing what it is for exactly, so he was happy to see my label maker and my active use of it.

We filled out the visit report and agreed to meet again after I’m further into the build and working on the interior of the Fuselage.

Vertical Stabilizer wiring

Now, back to building. As I finished the match drilling of the dimpled holes the other day, I had to dimple the hole that was missing a dimple, so I got out my modified hand dimpling tool and quickly did that dimple.

After that I worked on finishing the wiring the run through the Vertical Stabilizer for both the Anti-collision light on the Rudder, as well as the NAV Antenna.

First I had to make another hole to run the Antenna wire through the top rib since the factory plans assume that you either install the light or the Antenna, but not both. I marked the hole location using the center punch, then drilled a pilot hole and then used my step-drill bit to up-drill the hole to the right location for the snap bushing to go in.Center punch to mark the hole location Pilot hole drilled and ready to be drilled up using a step drill bit Finished hole and snap bushing installed

After that was done, I wrapped the wire for the light in some braided sleeving for some extra protection and then ran it through the rear holes. I also installed some flexible edge protection for the hole where the wire will meet the wire from the Rudder.
Wire for the light installed in the Vertical Stabilizer Flexible edge protection

Quick test fit on the Fuselage

I then quickly measured out the length of the Antenna wire to install in the Vertical Stabilizer, cut it to size and ran it through the front holes. After I was done with that, I wanted to do a quick test fit of the Vertical Stabilizer Structure on the Fuselage to see where the holes would pass through.

Quick test fit to see where the wires come out Looks almost like an airplane

Antenna Coax wiring

Once that was figured out, I moved on and did my first crimped coax connection. After a tip I saw on the homebuiltHELP channel, I bought this rotary coax stripper, which strips both the front, as well as the braided shielding in one go.
Rotary coax stripper

Before it was ready to use I had to do some adjustments for the lengths and depths for the cut, so I took it apart, while following the instructions and then moved the blade as needed. I’m using the SteinAir BNC Connectors, so I had to move the blade that exposes the outer shielding back by one position to the point marked E and the inner blade on mark B.
Blades set on mark E & B for the SteinAir BNC Connectors Correct location for RG400 stripping
Then I adjusted the blade depth using the screws on the bottom and did a few test cuts to make sure the results are repeatable. I then put some light strength thread locker on the screws so they stay in position so I can now just use it without any further adjustments needed.

After that I did a quick test crimp of a connector to the small piece of wiring I used to calibrate the wire stripper, following the instructions from SteinAir.
Test crimp successful

Looked all good, so I repeated everything on the actual wire for the Vertical Stabilizer.Wire stripped and ready to install the center tip Connector attached and ready for the back shielding to be crimped Completed crimp of the connector Test fit of the connector on the Antenna

With all that done, I installed the wire in the Vertical Stabilizer and now I’m ready to install the Antenna and close up the skin.

Interesting side note on coax wiring and the use of a balun

One other interesting thing I learned while doing this – I tested the wire I crimped for continuity to make sure there are no problems with the wire itself by checking (lack of) continuity between the shielding and the center core. This was all good, so my crimp is good.
After attaching the wire to the Antenna however, I figured I’d also check it with the wire attached to the Antenna and had a brief moment of confusion when I did get a positive continuity readying between the core and the outside. So I did some digging and found out that the use of a balun (in my case with the Rami AV-525, it is an internal balun) can create a DC short and thus will produce a continuous reading using a Voltmeter.

Vertical Stabilizer Navigation Antenna & skin fitting

Hours: 2.5

Before I can close up the Vertical Stabilizer skin, I need to fit the Navigation Antenna, run the wires for the Antenna and the rudder light and fit the skin including up-drilling the countersunk holes in the skin with the rib structure.

So one thing after another, first I gave a quick test fit for the skin and then drilled up all the countersunk holes.
Test fitting the skin and aligning everything to match up-drill the countersunk holes And found one hole that should be dimpled as well

After that was done, I went to work to fit the Rami AV-525 Navigation Antenna I’m going to use. I already fit the Antenna onto the inner rib a while ago before I built the rest of the structure, so now it was a matter of fitting it all with the skin to be able to close the skin around the Antenna.

On the left side, the Antenna comes out one of the pre-drilled rivet holes, so I just had to up-drill that to the correct size.
Enlarged hole for the Antenna on the left side

For the right size, the Antenna comes out offset a bit further behind, so I marked out where I needed to make the hole in the skin, then used a center punch to get a good center to drill the hole:
Marking where the notch for the Antenna has to go Centerpunched the spot for the hole to goHole drilled on the right side for the Antenna

With the hole in place, I cut back a small notch, so that the skin can slot around the Antenna since the arms of the Antenna are fixed to the internal balun.Notch to slot the skin around the Antenna

After all that was done, I put it all together for a final test fit:Left side view of the Antenna in place on the Vertical Stabilizer Right side view of the Antenna in place on the Vertical Stabilizer

Looks all good, so now I need to finish running the wires on the inside and then I can rivet the skin closed.

 

Vertical Stabilizer Structure

Hours: 3

After finishing attaching the rivnuts to the rear spar parts the other day, I put everything together and did a brief test fit with the Fuselage where it attaches into. Vertical Stabilizer rear spar in place with the Fuselage

After putting together the rear spar, I also enlarged the holes in the spar so that the M4 screws can actually be screwed in and enlarged the bottom two holes so that the bottom rivnuts sit flush with the spar.
 Holes enlarged for the M4 screws and bottom two holes enlarged for flush fit of those 2 rivnuts,Screw holes enlarged and the bottom 2 rivnuts made flush with the spar

Looked all good, so onto riveting together the inner structure of the Vertical Stabilizer.Riveting the rear spar of the Vertical Stabilizer Adding the inner ribs to the rear spar Structure coming along Inner structure of the Vertical Stabilizer riveted together

I also enlarged the holes for the wiring and added snap bushings since the inside won’t be accessible once it’s closed up and the snap bushings have a better durability than rubber grommets.
Snap bushings for the wiring

There was one spot on the rear spar where one rivet was very close to one of the rivnuts and I had to use my manual hand rivet gun to pull the rivet as the head of the Milwaukee was too large to get in there.
Clearance between the rivnut and the rivet was very tight so I had to use my hand riveter instead

Completed inner structure of the Vertical Stabilizer:Completed structure of the Vertical Stabilizer

 

Lots of Rivnuts on the Vertical Stabilizer

Hours: 1.5

After putting the Elevator construction on pause due to the alignment issue of the center rib. I decided to get started on putting together the Vertical Stabilizer. I’ve heard back from the Factory and it turns out that they’ve changed the Rib and will be sending me the correct new versions of the ribs (EL-RIB-001-C-E-1 & EL-RIB-101-C-E-1), so I’ll have to wait until I get those.

So onto the Vertical Stabilizer – the bottom of the rear spar holds a lot of M4 Rivnuts, so it was time to updrill the holes to the correct size in order to fit the rivnuts.Getting my tools ready to install the rivnuts

Using the step-drill bit I enlarged the holes just a bit smaller than the Rivnuts and then finalized it to the exact size using a hand reamer since you don’t want the hole to be any larger than the not so it gets a tight fit.
Hand reamer marked to the correct size using masking tape Test fitting Rivnuts after reaming them to the correct size

Once I was done enlarging all the holes I took care of deburring the holes and then went to work installing all the rivnuts using the Astro ADN14 Rivnut puller attachment for my drill and adding Loctite 277 (red) Threadlocker for added strength.Before deburring the holes after I enlarged them Tools ready to install the rivnuts Rivnuts installed using my bench vise to hold the bracket in place Done installing all the rivnuts

After all that was done, I put together the spar with the brackets for a quick test fit. While doing so I also found an error in the instructions, which say to rivet the hinges on the bottom with 8 (4 a side) 4mm rivets, but actually, only the center one (where I have black clecos) should be riveted, the outer ones will be bolted to the Fuselage (which is why they have larger holes already and I temporarily used the larger golden clecos to hold it in place), so I sent the Factory a note to correct the instructions.
Vertical Stabilizer Rear spar with brackets clecoed in place

More Elevator priming & assembling center spar structure

Hours: 5

With the weather warming up, I got to spend some time sitting in a bit of sun with the garage door open and preparing, deburring, cleaning and then priming more parts of the Elevator.

Laying out and preparing Elevator parts Primed Elevator parts

Assembling Elevator center spar

The first thing I put together was the Center Spar itself, which I had primed already together with the counterweight the other day. Setting everything up was pretty straight forward as usual and while I was working on it I had a visit from another builder of the EAA chapter I’m part of who actually happens to live very close by and is building an RV. And then another friend was visiting and I happened to have some rivets ready to be riveted, so I continue my new tradition to have guests pull a rivet on the plane and sign it.

Elevator Center Spar Elevator Center Spar riveted

Assembling the center structure to the spar

After the priming from yesterday had some time to dry and set, I went to work to put together the center rib assembly with the center spar. There are a lot of pieces that slot together in there, so it took some time to figure out what slots into which piece. for the center channel to go on:
Center Channel in place

Unfortunately I encountered a problem with the alignment of the holes on the center Rib, both left and right, with the plate as seen below:
Rib holes misaligned with the center plate Closeup of the misalignment of the elevator rib

In trying to figure out which piece is wrong, I started putting together more of the structure temporarily with clecos and the strange thing is that the other holes on the ribs are aligned fine (the black clecos below), so then I thought that it must be the top center plate.

More of the Elevator center structure in place

But then I took off the center plate to check its alignment with the outer skin and there the holes of the top center plate align correctly with the holes on the skin. So this in turn then lead me back to determining that the top (and bottom) holes on the Rib 1 must be the culprit.

It is very strange since the misalignment is pretty severe. It definitely doesn’t look like this could just be resolved by up-drilling the holes, so I sent a note to the factory to ask how to proceed. My guess is going to be that I need new center ribs.

 

Rudder Anti-collision light wiring

Hours: 2

Now that the Rudder is almost complete, I needed to make the wiring for the Anti-collision light permanent. The existing wire of the Aveo Posistrobe Minimax I’m using has 4 wires (ground, power, strobe, sync), so I needed to splice those onto the wire so I could run it through the structure.

Since this is a permanent connection, I’m using Heat Shrink Solder Sleeves, which have solder in the center and when you heat it up, the solder melts and the sleeve shrinks down to create a good seal.

After that was done, I added some expandable braided Sleeving over the wire for extra protection.
Expandable Braided Sleeving for the wire

I up sized the hole for the wire to pass through the fiberglass tip using my step drill bits and then ran the wires through the structure and out the front hole, which I also had to drill up as per the instructions. After some more research, I replaced the rubber grommets with snap bushings. They last longer and for the front hole in particular, they hold on better since they snap in place.
Finalized hole size for the wiring to pass through the fiberglass tip Snap bushing for the wire to come out of instead of using rubber grommets

Here’s the light mounted and completed wiring done.Light mounted and wiring finished

Now the last thing to do is close up the top. Inspired by a discussion from a while ago on the Sling Builders group, I was contemplating the idea of making the fiberglass tip removable using nut plates and screws, but I think I’ll end up just riveting it closed.