Rear Interior Skins

Time: 2 hrs

Today I labored a bit, even though it’s Labor Day and I’m supposed to be out having fun. I riveted the left and right interior skins. I can’t think of any reason I need to wait on these… famous last words. It all went very smooth, things fit surprisingly well. There were 2 holes at the very bottom of the skin that needed to be drill out and was a bit difficult to get the drill in to drill them out.

So with only a few things left to cover I really need to get the engine ordered. I’m away for 2 weeks in Germany to run the Berlin Marathon so maybe I can get it ordered before then.

Photo of right side rear interior skin done. Left side looks the same so didn’t take a picture of that.Seat belts work great as well.

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Rear Seat Back Stops and ELT Antenna


Time: 2.75hrs (includes .75 avionics time)

Today I did some work on the interior section behind the rear seat. Prior to installing the rear seat stops I riveted and covered the area with carpet. I also had to drill a few missing holes in the rib. For the ELT antenna I put in a few M3 rivets so that I could remove the antenna if I decide to move it to a new place. Unfortunately the only better place I can think of would be just in front of the vertical stabilizer inside the fiberglass and running cable back there will be quite involved. I’ll try this out and if it doesn’t work then I’ll have to move it. I also made a mistake and mounted the antenna a bit too low on the rib. I forgot that the BNC connector would add about an inch to the length of the cable. It would have worked but it was a bit too close to the luggage support and I didn’t want the connector to vibrate and have issues so I moved the antenna up about an inch and installed 2 more rivnuts. I covered the other rivnuts with carpet. I also drilled out the top line of holes in the side inner skins (the holes that go into the fiberglass of the canopy).

The ELT mounted using 2 M3 rivnuts onto the rib. Covered the area with carpet and installed the seat stop. I also drilled a hole in the luggage support and installed a grommet for the antenna coax cable and crimped on the BNC end. I put some large diameter wire sheathing over the BNC connector and cable, just thought it looked a little nicer. I still want to install a few clips to hold the antenna on the rib.

Carpet installed and rear seat back stop installed as well. I will have to check how well the latch on the rear seat works. I saw that Peter C. added extensions on the seat stops because they barely reached the latch. I may need to do the same.

Rear Floor Panels

 Time: 2.25hrs

Today I riveted the rear floor panels. The brake lines have been run for a while now. I still need to clean them out and then put the brake fluid in, but I think it’s safe to install the floors now. I did a few things to the landing gear bolt inspection covers. First I rounded the corners a bit and then I use the edge tool to put a bit of a raised edge so that the M4 rivets would fit well underneath the cover. The cover sits a little higher then the rest of the floor, but I’ll have some fairly thick carpet so I don’t think it will be noticeable. It would have been better to use M3 screws and rivnuts, but the predrilled holes were a bit too large so I think M4 worked better.

floors riveted and (3) M4 rivets installed in the floor for the inspection cover.

Inspection cover came out pretty good. Need to prime it though.

Yay both floors are in. Have to do the sides next and then a little more carpet covering

Close up of the inspection cover. The edges are beveled a bit so that the rivnuts can sit under it and I though the rounded corner looked a bit nicer then the squared off, plus the beveling comes out a bit better if there’s not a hard corner.

Miscellaneous Work

Time: .75hrs

Did a few things on the plane today. First was I finished up the throttle assembly and put on the turbo boost handle and main throttle handle since I don’t think I will be removing the throttle assembly anymore. Previously I had made an error and reamed the hole on the throttle arm out a little too much so I had to get another one from TAF. The bushing that goes in the throttle arm should rotate freely so that the throttle cable can move back and forth, but the hole on mine was too small. I reamed it to 7mm and then just lightly filed around the hole to get a perfect fit with the bushing.

Second I did a bit more work getting the front seat straps to move freely between the canopy and the interior skin. I had thought that maybe I didn’t put the canopy on far enough back. However, after looking at another Sling 4 at TAF it seemed that it also had the same issue where the seatbelt strap cut out wasn’t back far enough to accommodate the way the seatbelt strap routes up from the spool to the hanger (mounted on the canopy). Even with the cut out not extending back enough the strap did still work, but it did seem to stick some times. After extending the cut out by around 1/2″ the strap doesn’t seem to bind up at all. I also added some low friction tape to the inside of the side skin just to help a bit more (but not really necessary). The side skins should be ready to rivet now so I may do that tomorrow.

Used the deems to extend the cut out for the seatbelt strap. This will all be covered by the side panels so the little missing paint isn’t too big a deal.

The seatbelt moves nice and smooth now and there’s no bend in the belt as it passes through the cut out now. Previously it did work OK, but now works without any binding.

I added a little low friction tape to the inside (that you can’t see) of the skin and then wrapped it around to the front.

Interior Rear Side Skins

1.5 hours

Today I got the interior rear skins ready to get riveted. I had to remove a few rivets from the rear seat floor area to get the skins to fit in. I also had to drill out a few holes for rivets. The skins fit pretty well. The only issue is that if I line up the top of the rear skins with the top of the front skins then most of the holes don’t line up so having them not even seems to work best. These will be covered with the more decorative interior panels so these will never be seen.

I noticed that the cut outs or recesses in the canopy for the seat belts don’t line up great. And since the parachute cable is right behind that area I can’t really even dremel it out more. It’s not that far off, maybe 1/4″ and the seat belt does seem to move OK, though it got a little slow retracting once while I was messing with it. I was thinking maybe the canopy isn’t far enough back (not much I can do about that now), but if that were the case then the upper hinge part of the seat belt strap would be farther back as well and so I’d have the same issue I think. It’s not that big of a deal, it would just be nice if it lined up a little better. Maybe I might need to loosen the seat belt spool and put a slight angle on it instead of it being so straight vertically. Will have to look at that.

I always thought the these flanges go in front, but I saw on the Sling at Torrance TAF that they sit behind the floor panel. Much easier to drill out as well. But now I need to remove these rivets.

OK rivets are out and had to drill one hole in the flange on the floor. On the floor I put the flange under the floor skin even though the Sling at TAF had it on top. I just think it looks better and maybe a little stronger this way.

Right skin, cleaned and clecoed. I’ll do the top row after I get all the other rivets in. Just need to rivet it when I get back from my hiking trip. I think I should be safe to install the interior skins now. I can’t think of anything else that needs to be done behind them.

And same for the left side.

Install Center Console (Cubby Hole)

Time: 1.5 hrs

Today I made the cubby hole/center console assembly a permanent resident of the plane. It’s been a long time waiting to install this piece so I’m happy it’s finally in. I also install the front seat belt buckles. I added 3 thick AN4 washers on the inside since the hole to mount the buckle is so large. The washers filled the gap well, a little bit of play in it, but much better then mounting without them. With the cubby hole mounted I was also able to install the inner seat rails.

Now I can double check that the brake lines are routed correctly and everything reaches. Next I can cut the lines at the clippers and put the -4AN ends on. I purchased some 45º fittings which look like they’ll work great.

Cubby hole and seat rails in. I will need to install the arm rest when I get that some day.

Rear cover for the cubby hole/center console. The stratus is mounted towards the bottom. This will be great for the kids and also can serve a 2 more USB chargers for the front. The Garmin GMA245R has one that I’ll need to bring up the the instrument panel with an extension, but it’s always nice to have a few more around. I’m thinking of also putting the rear LEMO plug here for the rear seat headsets.

Rear Seat Camlocs

Time: 1.0 hr

I originally installed the retaining springs for the DZUS locks that hold in the rear seat, but after a post on the Sling Builders Facebook group about using 4002 Camlocs on the cowling I decided to make everything the same and replace them with the 4002 camlocs. In my internet searching to learn a bit more on how to install the camlocs, I came across Skybolt which has some very nice 4002 compatible camlocs. The cost is a bit more then Aircraft Spruce, but they seems to be a better quality then what you get from Aircraft Spruce. The other issue was I had to order a minimum to get the ones I wanted. Since I only needed enough to do 3 anchor points I had to order a little more then I needed.

Here’s a little on what I learned about the camlocs. First there are 4 piece and 3 piece systems. Typically you use the 4 piece. The 4 pieces are the grommet, the retaining ring, the stud, and the receptacle. The 3 piece have the stud and grommet as one piece. You can get studs in different lengths which is specified by the -(number) in the part so something like 4002-14 or 4002-5. The numbering of the parts are super confusing because there are a multitude of faster types you can get like slotted, phillips, winged, etc and you can also get different materials (cad plated, stainless steel). The grommets come in basically normal width and wide width and only a few different depths. The one confusing thing for me with the grommets was that the “plus flush” are the grommets that aren’t actually flush, they don’t need to be counter sunk, that’s the “flush” grommet. To me is sounded like the “plus flush” was just better version of the “flush” grommet, but that’s not the case. The last thing I need to mention is that you can technically install these without any special tools, but its a pain in the butt and pretty much impossible to get the stud out of the grommet if you don’t have the special pliers (showing below). Same with the retaining clip. You can get the thing on, but its a pain. The tool that they make to put the retaining clip on makes it supper easy and its only around $20 from Aircraft Spruce or Skybolt (the pliers are fairly cheap as well). I haven’t purchase the retaining ring removal pliers, but maybe I will get those at some point.

So with that said I ordered some nice folding wing fasteners from Skybolt. These are the 40S47 style studs, but Skybolt calls them SK4002SFW folding wing. I like these because they sit fairly flush, but you don’t need any tools to remove them. The -9 seemed to be the perfect length. If you like them and want to use them on your Sling please let me know. I had to buy 10 and only needed 3. I will sell you them at cost which was around $8.50 or so. I also used the wider grommet which was just for aesthetics.

Parts that I ordered from Skybolt. I had also order some phillips style studs, retaining clips and flush washers from Aircraft Spruce. The pliers are for compressing the spring on the stud when inserting it into the grommet (after the grommet is installed with the retaining ring). The tool with the rubber end it the tool to install the retaining ring onto the stud.

Above is the process to installing the grommet, retaining ring and stud. I used a step drill to enlarge the hole to 15/32″ (approx. 12mm). The grommet doesn’t fit supper tight, it moves around a little in the hole, which I think is the way it is supposed to be.

I added a little more neoprene tape to the back of the rear seat so it doesn’t scratch up the luggage floor. I’m not going to install carpet on that part so it needs a little something.

The receptacle installs much like the DZUS springs using 2 counter sunk 3.2mm rivets. I did need to use a step drill to widen the original hole to 5/8″ (approx. 16mm) so that the stud and grommet fit down into the receptacle. The receptacle are the 244-16 style receptacles (from Aircraft Spruce). The -16 have the rivets spaced at 1″ as apposed the the -24 which is wider (like 1 3/8″ I think). The -16 style line up perfectly with the mounting holes for the DZUS springs so those holes can be reused.

Everything installed. The wings on the studs fold down so the sit fairly flush. Its super easy to take out the rear seat, just fold the wing up and twist 1/4 turn.

Now the big question is what was TAF’s intention for the hole towards the from of the rear seat and bracket with the 2 holes on the rear spar? The hole in the seat appears to lend it self to installing the stud side of a DZUS connector, but the bracket doesn’t look like it would get the spring installed. The Sling 4’s I saw at TAF didn’t have anything installed here, just the 3 on the rear portion of the seat. So probably not important, just more curious then anything. I was thinking I could maybe make a sliding latch here so that when you install the seat it would slide down into the latch and then you use the 3 camlocs to loc it in place. the purpose of the slide latch would just be to keep the front of teh seat from lifting up.