Engine Control Cables

TIme: 2.5 hrs

Today I started to install the bowden cables for the choke, throttle and cabin heat. I had previously purchased McFarlane cables for the choke and cabin heat, the throttle cables I was able to get from TAF separate from the firewall forward kit (since I didn’t purchase that kit).

The cabin heat and choke cables needed to be cut to length. I used the Dremel with a cutting wheel to carefully cut through the outer metal sheathing to the teflon core, then I used a razor blade to score the teflon core and just twisted the cable to break that all loose. Not as bad as I though it would be. The choke cable was fairly easy and seems to work well. It’s a bit hard to pull, but may get a bit easier over time.

I also installed the throttle cables, but I need to wait until I can get power to the TCU and connect a laptop to the 9 pin on the engine to verify that the 104% throttle position is correct. I followed the Rotax manual for setting the throttle cable which is to put the cabin throttle lever in the idle position and then place the actual throttle on the carburetor into the idle position and then secure the cable. You do this for each carburetor. This seems to work out OK, but I do reach full open throttle on the carburetor a tad but before the cabin throttle lever has reached the max open throttle position, this is why I’d like to check that the detent on the lever matched 104% on the carburetor before I finalize the install of the throttle. The one thing to be aware of with both the throttle and the choke is that they are spring loaded. For the throttle this means that the default position is wide open throttle and pulling back the throttle lever to idle has a bit of resistance so the bolt that connects the lever needs to be somewhat tight so that it holds against that resistance of the spring. The choke is normally closed and then you pull against the spring to open the choke so you need to keep your hand pulling the choke open while you try to start the engine and adjust the throttle as needed with the opposite hand.

Choke cable done. I put some safety wire as shown in the Rotax manual or I have seen people use heat shrink on it. the cable end uses a round stop that fits into a slot in the choke lever on the carburetor. The throttle cable is connected, but I want to verify the 104% position before finalizing it.

Will update soon

Instrument Panel Installed

TIme: 4hrs

I was planning on waiting to finish the GNX wiring and install the panel until after the paint was finished, but the paint is taking longer than expected. Basically I need to wait until Carlos has some time between painting the TAF customer planes and they’re very busy so just trying to be patient.

Anyways the panel install went a little more difficult than expected. I had done a test fit prior, but it seems that some of the M4 screws were determined to cross thread so that was a time sucker getting that all straightened out. I really hate the fine threads of the metric screws, if the screw isn’t perfectly aligned then the screw tries to cross thread into the rivnut.

Once the panel was mounted it was just a matter of connecting all the miscellaneous avionics and doing some final tie wrapping and cable clean up. I also checked continuity on quite a few of the connector pins to verify that they are connected to the correct place.

One last photo of the mess that is behind the panel

Just a few photos of the completed panel. Steve at Midwest Panel Builders did a great job cutting the panel from my CAD drawing (and I’m sure they needed to fix quite a few things). Everything fits perfectly. Now I need to program the VPX and the Garmin stuff then do a bunch of testing.

Wiring GNX375

Time: 6hrs

I started to wire up the GNX375. This is the last piece of avionics that needs to be wired. Once this is done I can permanently install the dash. The GNX375 uses the smaller 22D pins to fit into the high density connectors which I find a bit more challenging to get the pin onto the wire. Maybe because my old eyes are starting to go a bit. Also the transponder and GPS antenna cables need to be terminated. The Transponder cable gets a BNC connector while the GPS uses a TNC connector.

It looks worse than it is. I got the antenna wires terminated and all the pins on the wires with labels. There are quite a few serial and ARNIC wires that need the shield drains put on as well.

I need to install the config module in the connector hood and also double check the pin outs to make sure all the wires are going to the correct pins.

UPDATE 04/07/2021

Today I finished dup the wiring of the GNX375. That I believe is the last of the wiring that needs to be done. This weekend I’ll install the panel and then can install all the avionics, plus the heater and choke cables. Also I can start testing the electrical system and configure the VPX. Now if I could just get this thing painted I’d be pretty close to a first start.

Wiring on J3751 with the config module installed

Finally all done. The plate that all the connectors mount to will be installed into the back of the rack when the panel gets permanently installed. The GNX then just slide into the rack and the connections are made.

Fuel and Oil Vents

Time: 2.5hrs

I made some ends for the fuel and oil vent drains out of some stainless steel tubing. The fuel is 1/4″ OD and the oil is 5/16″ OD. I put bypass cut outs in the side of the tubes so in case the end get clogged it can still drain, but I’m thinking I should put it up higher. The main reason to do this is so if the end ices up, but the bypass is then put on the inside of the cowling. Since I’m not making a hole through the cowling then I figured I’s put the bypass cut near the end, but now I’m thinking it should be up a bit higher on the tube. Well not too hard to make up 2 more tubes if I decide to do that.

I’ll need to attach the hoses to the tubes and put on some clamps as well.

UPDATE 02/21/2021

I remade the tubes and made them a little longer with the bypass cut out up higher. I also attached the 2 hoses to the tubes and clamped the hose in place.

The tubes are mounted using adel clamps. They move a little, but are in there pretty tight so should be good.

The tubes sit just about flush this the cowling so shouldn’t have any additional drag from them… not that they would attribute to that much drag.

This is a burry photo of the bypass cut outs to allow for the overflows to work even if the ends get clogged or frozen.

Wing Light Covers

Time: 10.0 hrs

Since I need to finish up the wings for paint and I wanted to dimple the holes for the wing light covers I figured I should get that done now. I kind of thought this was going to go along pretty easy, but the covers don’t fit very well. I thought maybe I had the incorrect parts. Both are labeled Sling 2 Right. In checking the part number though and also checking the parts list for the wings it seems that the same part is used for both the Sling for and Sling 4 and the part also doesn’t have a left or right since it seems you can just flip it over and out will fit the other side. With that said the right side seems to fit OK. It’s difficult to get some checks into the holes of the plexiglass because it easily bends and is hard to pull it down so the cleo can reach the hole. However once you get some checks in there the holes seem to line up and it fits pretty well. The left side though doesn’t fit as well. I have tried a few different ways and I can’t get it so that all the holes line up so I’ll move ahead using the orientation that the most holes line up and just drill out new holes for teh ones that don’t

Because I’ll be dimpling the hole so I can use counter sunk screws rather than the wood screws they city comes with I’ll need to make some backing plates that I can attach to the back of the plexiglass that will have the nuts that the screws can screw into. I’m planning to use some “captive nuts” like what I used on the instrument panel. The nuts are pressed into the holes from the back so the front is flush.

I made up some backing stripes out of some 1/2″ width 1/16″ thick aluminum. I bent the fronts to match the shape of the inside of the leading edge skin and drilled out 5/32″ holes to match the holes in the plexiglass.

Holes are almost all dimpled using 1/8″ dimple die. I’ll use either M3 or 440 counter sunk screws so 1/8″ should be good for the dimple so the head of the screw sits flush with the skin.

Well I got this one to fit with the backing strips inside. I’ll need to figure out how to hold the backing pieces onto the plexiglass. I’m thinking the plexiglass should be thick enough to use some 2.4mm countersunk rivets. Also I ended up splitting the front side strips into 2 pieces (4 total) rather then using 2 large strips because once the plexiglass bent it seems like the holes didn’t line up so well. I may give it a second shot and make up more strips and see if I can get a better fit.

UPDATE 2/13/2021

I remade the side strip pieces and got them to fit better. I should have made them after I did the dimpling since that caused the internal dimensions to change a bit and threw off the mounting hole locations. I also drilled out larger holes in the plexiglass to fit around the dimples rather then countersinking the plexiglass.

Drilled out the mounting holes in the plexiglass to 17/64″ rather than trying to countersink teh holes.

This is how it all fits together. I still need to install the captive nuts in the strips. Then I plan to use some clear RTV to temporarily bound the strips to the plexiglass so that I can fit the assembly into the wing and cleo it. This should position the strips where they need to be. Then after the RTV dries I can remove the cover assembly and put in some 2.4mm countersunk rivets to permanently hold the stripes onto the plexiglass.

I’m also going to contact TAF about maybe getting another left cover. I can probably make the one I have work, but since the holes are already drilled and I had to drill some new ones, it’s not really correct. If I can get one the fits better and the holes line up correctly then that will help. If not what I have will technically work, it just doesn’t look so nice.

UPDATE 2/19/2021

I attached the medal strips tp the plexiglass with a few 2.4mm countersunk rivets. The plexiglass is thick enough to get a good enough counter sink so the rivet sites flat.

These are the captive nuts I’m using. They press into the metal strip. They’re almost impossible to get out once they’re in, well unless you drill them out. They’re stainless steel so they’re fairly strong, though I’ve had a few instances where the threads seem a bit tight when screwing in the screw so I’m going to try to tap them out with an M3 tap. I’m thinking I should have gone for using M4 screws since the thread aren’t so fine as the M3. Well I think this will work and hopefully none of teh screws will get stripped when I put the cover on.

UPDATE 02/21/2021

Well I got the right side cover on. I had an issue with a screw that cross threaded so I tapped it out with a M3 tap and seems good now. I also remade the strip on the inner side because the holes didn’t line up exactly so the screws were going in too tightly. I found that if I drilled the hole that attach the strip to the plexiglass first and then hold them in place with 2.4mm screws and then drill the main screw holes that makes it very accurate and the screws then going in nicely.

Finally got things to line up well and all the screws go in. Will need to do the same for the left, but I’m seeing if I can get and actual “left” part to see if that fits between teh flipping the “right” part over to make it a “left” 🙂

A few photos of the finished cover. I’m pretty happy with how it finally came out. A few little things not exactly right, but seems to mount into the wing nice and tight with no gaps around the edges and all the screws go in easily.

UPDATE 02/23/2021

I was able to get the left wing light cover to work. There are 2 extra holes that were pre-drilled by TAF, but the holes are hidden by the skin so no big deal. The cover fits really well.

Glad these are done. This took way longer then I thought it would, but it came out pretty good so I’m happy that it all went together well.


I’ll keep updating this post with any progress made to painting the plane. Today I got the main wheel pants back from Carlos. I’m slightly disappointed, but still think they came out fine. I’m disappointed because I thought I did a much better job prepping them, but I see a few areas where I should have paid closer attention. This is mainly the seam area. It’s not bad but there are a few spots where I can see the dip where the seam is. I do like the color and Carols did a great job with the paint. I’m just going to have to do better at the fiber glass prepping and I told Carlos that if he needs to spend some time fixing areas I miss then it’s worth the cost to me for him to do that. So I’m hoping the rest of the project will get better, but that’s why we did the wheel pants first.

For paint I ended up going with BASF base coat, clear coat. The BASF paint is waterborne so it’s easier to work with and seems to cover really well so we’ll end up using less than solvent based paint. For the clear I’m using Glasurit 923-210 which is made by BASF.

I think the color is going to look great. I’m going to use stainless steel screws everywhere w/ nylon washers. Also I’m thinking I’m going to line the top part (neck) of the inside of the wheel pants with some neoprene foam so that it doesn’t scratch up the landing gear. I noticed on other Slings that the wheel pants rub a bit and after time the paint scratches. Unless you cut the neck back a lot it’s probably going to rub a little. Mine have a very small gap, but if it shakes or vibrates then in may rub on the gear.

Just a photo of the other side.

UPDATE 2/2/2021

I added some neoprene to the inside of the wheel pants where it may rub on the gear so it will lessen the paint getting scratch.

And on the part that mounts to the brackets on the gear

I’ll be sending the nose wheel pants and the the HS off to get painted don Friday.

UPDATE 02/05/2021

The spinner is now black 🙂 I sent the HS and nose wheel pants to Carlos. He’s going to try to start painting them on Wednesday. We need to figure out the templates that I purchased from Plane Schemer. They are low tack templates that stick on, but we need to experiment a bit on the order of the paint colors and how to best use them.

UPDATE 2/12/2021

Carlos primed the empennage and sent me some photos. He’s going to do the silver and one coat of clear then we’re going to sand and put on the template to paint the blue and black.

Alodining the parts prior to paint so the paint sticks better

UPDATE 2/19/2021

Carlos came by the hangar and helped me get the stencils onto the HS and elevator. He should be able to spray this next week along with the nose wheel pants. The whole HS and elevator needed to be sanded with 800 Grit paper and Ultra Fine Scothbrite. Next the blue will get sprayed and a thin layer of clear, then that needs to be sanded and then the black. Once the black is done then a few more coats of clear to finish it. Thinking that this will need to be done to the fuselage and wings makes me think how much work this is going to be… aahhhhh. But it’s just so time consuming and not very difficult to do so it’s worth the effort to do the work myself.

So to the tip side will be blue, plus a thin line on the other side of the black (first yellow section). The first yellow piece of the stencil is where the black will go. The second yellow part after the thin line (that will be blue) is just there to protect the grey. Once the blue is sprayed then both the yellow sections can be removed. Then the blue will need to be masked to leave only the black area so that can be sprayed. That’s the reason why the blue will need some clear on it, because the tape will ruin the paint.

UPDATE 02/25/2021

Carlos stopped by and picked up the HS and Elevator. He was able to get the blue painted and sent me some photos. I’m pretty excited to see the 3 colors all together. I hope it looks good. I’m thinking that rather then do the wings next, maybe do the fuselage. That way I can start putting things together while the wings get painted. Also I think I came up with a good plan on how to tackle the paint on the fuselage that should cut down on the amount of sanding and also maximize teh work that can be done in the hangar rather than at the paint place.

A few photos Carlos sent of the blue going on to the HS, elevator and nose wheel pants. Next is to clear coat and sand the blue, remove the stencil, mask off the blue and silver and paint the black.

I also got the cowling pretty much ready to go for painting

And started prepping the doors as well.

UPDATE 3/1/2021

Today I put the stencils on the VS and rudder. There is more stripping that will be done to these when the stencil is put on the fuselage, but good to get this one done now.

I labeled the yellow section with what color they will be (or are) to try to reduce confusion. Most of the upper portion of the VS and rudder will be blue.

UPDATE 03/03/2021

Carlos should have the HS, elevator, and nose wheel pants done this week. It will be good to see all the colors together. I hope it looks OK. I’m now trying to get the fuselage ready to get the paint done next. I’m also trying to figure out this large fuselage stencil. I’m thinking I’m going to have to maybe cut it into a few parts to make it easier to manage. I removed a lot of the material so that it’s fits around the fuselage better. The difficult part is where is wraps in to the empennage fairing. The stencil doesn’t like to bend that much and I think that because it was made from a flat drawing it may not be long enough if I were to pull it in to fit against the fairing. I’d like to get the part of the stencil that goes on the rudder and VS stuck down so they can be ready to paint. This will require cutting the stencil after the fairing since the fuselage isn’t ready, but I think that’s a good place to make the cut. We can always extend the lines with tape if we have to, just the angle of how the striping will run needs to be correct.

This stencil runs along the whole side of the fuselage and is pretty hard to manage. I removed a lot of the unnecessary material to make it easier to work with. I also remove the black stripe that will go from the cowling to the rear fuselage over the window area. I think this will be easier to do as a separate piece after the blue paint is done.

UPDATE 03/15/2021

Got some of the parts back from paint. I love the blue. Just happy that all the colors look pretty good together. I also got all the stencils on the VS, rudder and empennage fairing.

Rest of the stencils added to the VS, rudder, and fairing.

A few photos of the finished HS, elevator and nose wheel pants (well half of it).

Carpet Fix

Time: 1hr

Tested my sewing skills today. Back when I was fitting the carpet I had to cut the front pilot and copilot floor carpets a bit since I carpeted the center console area a little differently which required the floor carpet needing to be cut back on that edge where is meets the center console. This would have been easy if there wasn’t any velcro needed to hold that edge down, but there is so I had to sew back a strip along that edge.

I used some sticky back velcro to make it a bit easier to position the stripe for sewing. Then I had to remember how to setup the sewing machine. Eventually I figured it out and the actual sewing only took a few minutes.

The completed product. I used a bit heavier thread then usually so I also purchased a thicker #18 needle to accommodate the thicker thread plus get through the plastic of the velcro and thick carpeting material. I think it came out pretty good.

The back side showing the velcro strip.

Wing Connections

Time: 3.0 hrs

Today I started work on getting all the various connections done between the fuselage and the wings. On the right side there is the fuel feed (-6AN), fuel return (-4AN), and a 9 pin connector for the lights and fuel sender connections. The left side has a a few more connections being the pitot/AOA tubing and connections for the pitot heat. Nothing too difficult about connecting this up.

Since I put in an adel clamp to hold the connector on the wing side there’s not a lot of space for the wiring to run from the fuselage to the connector so I’m going to just loop it around. I’ll tie this down with some cable ties or something, still need to mess with this a bit. The longer cable coming out of the fuselage makes it a bit easier to work on the connector as well.

I’m wondering if I need to put AN bolts in those holes there.. I’ll have to ask Jean or the factory. The manual doesn’t;t say anything about it.

It’s been a while since I worked with putting the ends of the rubber hose for the fuel lines. On the first -4AN fitting I just used a bit of chain oil and I barely got the end on the hose with quite a bit if force. I then remembered heating the fuel line at around 200 degrees with the heat gun made a world of difference in getting the ends on the hose.

Still need to get the pitot and AOA tubing connected and the connectors for the pitot heat. There’s quite a bit of space to work in this area so not too bad to connect things up.

UPDATE 1/19/2021

Finished dup teh connections on the left wing. The left wing has the pitot tube so these a few more connections that need to be made. For the higher amperage pitot connections I just used what Garmin used which are the spade type connectors. The pitot and AOA tubing was connected using a Nyloseal connector.

All the connectors are on. I’ll clean this up with some tie wraps . Most of the wing connections are through the TE Mate-N-Lok circular connector, but because ether pitot is a bit higher amperage then what the circular connector is rated for I just used the spade type crimp connectors. My pitot also has a sensor wire that tells the EFIS if the pitot is on and at temperature. The blue and green tubing is for the pitot and AOA from the pitot tube. Also shown are the -4AN hose for the fuel return and the -6AN for the supply line.

TAF Service Bulletin #0014 Complete

Time: 1.5hrs

Finally finished up SB #0014 which was to replace a number of rivets in the main spar with stainless steel rivets. Since I have the wings on I decided that it would be a good time to do the rivets along the bottom of the fuselage. Having the wings on will keep the space that needed for teh wing spar to fit into the fuselage spar. I was kind of dreading this, but it turned out to go very well. My only casualty at this point is I can’t locate 2 of the rivet tails from the rivets that were removed. I’ll keep looking and maybe when the wings come off I’ll find them in the spar channel.

First step was to drill out the 62 4mm rivets that run on the bottom of the fuselage.

All the rivets removed along the spar. My technique for removing the rivets is to drill the head using the same size bit as the rivet, in this case 5/32″ (4mm), I use the slow speed on the drill and stop as soon as the head spins off. Then I use an auto punch to punch out the rest of the rivet. Occasionally you’ll get a rivet that doesn’t want to come out or the mandrel punches out and you’re stuck with the shaft of the rivet still in there. Usually you can get those out by using the auto punch at an angle to press against the remaining part of the rivet. If that doesn’t work you can very carefully drill it out using the same size drill as the rivet.

All the rivets replaced with stainless steel ones and put some filler in them as well. Will have to sand them later. I used some recently expired tank sealant on the rivets to serve as an anticorrosion barrier between them and the aluminum skin.

I already did the rivets on the wing spar when I was building the wings so that should be everything needed for the SB.

Wings Test Fit

Time: 4 hrs

Today I got the wings on with the help of a good friend. I wanted to do a test fit of the wings prior to getting them painted and it was good that I did. Even though I checked the cut out for the landing gear it did prove to not be cut back far enough so that needed to be done. I also learned a few things that I’ll need to be aware of when I mount the wings for good so that I don’t damage the paint.

My wings fit pretty tight into the fuselage. I had to rock the wing up and down and push in at the same time to get them in. Also it was a bit of a pain to line up mount holes in the spar. I think next time I’ll remember to use the large awl I have so that I have something that can go in the hole and can be tapped in to line things up a bit quicker. For this go around I just used some A7 bolts I had from the wing jigs. I didn’t want to use the actual bolts since I didn’t want to damage them in any way. I only put in 2 bolts per wing and the bolts did fit pretty tight even though I tested their fit in the fuselage spar and the wing spar prior to fitting the wings.

I think one thing that would have helped is to have something supporting the wing at the root. I did put a saw horse under the wing about mid way to allow us to rest the wing while we messed with other things, but the wing kept wanting to slip downward and the large flange at the bottom of the wing spar bent the bottom skin a little. Not too bad and it gets covered by the wing skin overhang and fairing so not a big deal. But I think for next time I’ll cut down a saw horse to fit right at the wing root to keep that at a good height while pushing and wiggling the wing into slot in the fuselage.

Had to cut this back about 1/4″, just about right the the rib flange. I had measured before and compared mine to another builders measurement and it seemed like my wing skin had already been cut to the correct size, but it definitely interfered with the gear.Fortunately it didn’t cause any damage to the gear itself.

Sorry bad photo, but trying to show that the cut goes almost back to the rib flange.

After much work the wings are on.

Happy that the wings are on so another photo.

So with this done. I’ll now prep the top of the wings for paint. I can also finish up the wiring of the wing connectors, pitot/AOA lines and the fuel lines as well and can also finish the service bulletin work. I’ve been contemplating if I should do an engine start. I’d need to put on the prop and a few other wings, but it would be nice to get that out of the way and not have to put the wings on again prior to moving to the test airport. I just don’t know if by putting on the prop I’m open myself up for possible damage while it gets painted. Hmmm will have to think about this.