Left Wing Top Skins

Time: 8.5hrs

Finally got the top skins riveted on the left wing. After finishing up the wiring and testing the pitot tube electrical I figured it was safe to close up the wing.

I had a few holes on the rear spar that slightly didn’t line up (same spot as the right wing) so the holes needed to be elongated a bit. I had one area near the rear spar and skin join that I noticed some oil canning before I riveted it so I tried a few things to get ride of it like checking all the holes to make sure the rivets weren’t in too tight and pushing on the skin and reclecoing the section to see if that could alleviate the issue. Nothing seemed to work so I carefully started to rivet and see if it got worse or better. I riveted in such a way to try to smooth out any lump in the skin (that I couldn’t really see) and also tried to pull the skin a bit to make it tighter. The oil canning still persisted. As I riveted and was nearing completion of the area I though to myself that I’ll just need to drill out most of these rivets and try again. Then to my amazement I put in the very last rivet which was probably 10 or so rivets towards the root along the rear spar away from the section that was having the issue and checked the oil canning… it was gone. One rivet that was seemingly not even related fixed it, so freaking weird. I think that’s what makes fixing the oil canning so difficult. The rivet or rivets that are causing the problem could be not even in the area where the problem is. Frustrated and confused, but glad it’s fixed

Another thing I noticed and it’s kind of funny that I just caught this now (as I near the end of the riveting stage of the build) is that the rivets are not all exactly the same. There are some variations in the size of the rivets. I first noticed it using the 4.8mm rivets on the ribs. It seemed like a rivet should fit fine in a hole, but it didn’t and then I used another rivet and it fit fine. The same is true for the 4mm rivets, maybe not so much for the 3.2mm ones though. So what I got out of this was that if you’re putting rivets in the holes and the rivet is fitting a bit tight, rather then ream out the hole or trying to get the rivet in with more force, just try another rivet. In most cases if you go through a few rivets one will drop right in.

left wing ready to rivet

Both wings have all the skins riveted. Now I need to do the fuel tanks and the wing tips.

Left wing all done. Just have to fill all these rivets.

Starting on Fuel Tanks

Time: 8.0 hrs

Started working on the fuel tanks. So far I prepped, cleaned and alodine most of the internal tank parts and also started to test fit the parts that go on ribs 101 and 105. I’m only going to alodine the surfaces that are on the inside of the tank since I will be able to spray some primer on the other surfaces once the tank is sealed and and leak tested. I’m just doing the alodine to protect the aluminum from corrosion. It probably won’t even matter, but better safe than sorry.

Box of alodined parts. Also did all the ribs as well. I’ll also need to do the inside of the tank skin and the inside of the back piece. I’ll probably just brush the Alodine on those parts because I don’t have anything large enough to submerge them in. The brushing actually works well, it just takes a bit longer.

Started to assemble the fuel level senders. You have to disassemble the parts that come in the box and then reassemble them on the mount that is provided by TAF. Once I get them finalized I’ll mark the sender assemblies as Left and Right since it will make a difference which side they go on.

The various fittings that go on the inside of rib 101. The bracket that holds the fuel pickup was kind of a pain to bend, but it came out pretty good. I had to ream out the holes on the backing plate to the size o the M4 rivet and also had to file the hole where the AN6 fitting goes (for the fuel pick up). I didn’t want to use a step drill on it because I want the fitting to fit nice and tight so it won’t leak. It will also have sealant on it when it gets installed, but the tighter the parts fit the better.

This is the fuel sender that’s used. It’s a VDO sender 10-180 Ohms

Wing Dolly

Just a quick post about the wing dolly I made. Not quite ready to put the wings on it though. I used some plans I found on a Google search off the EAA website. I modified the length of end posts a bit because I may end up storing the wings with the tanks off for now, until I get all the parts to build them.

Here’s the plans I found. I also used metal brackets instead of the wood braces because I’m just lazy. I did use one wood brace for the uprights to the cross pieces. I got the wood from the cover to the shipping crate the spars came in.

I also used one set of steerable casters and another that are fixed so I can pitot the dolly around. The handle is on the side that steers.

I think in all it cost me about $75 to build the dolly, but I had a few 2×4’s already. The most expensive part was the tow strap which was around $20.

Some photos of the finished dolly. I still need to determine the length of the straps, but will do that when I have a wing to put on it. Not quite ready yet to do that.

Pitot Tube and More

Time: 8.5 hrs

I got the pitot tube installed, wired, plumbed, and pressure tested. Installation was pretty easy. I hadn’t done any flaring yet so it took a few tries to get it right. I followed the instructions that came with the flaring tool and I did 6 twists, that left the flange too wide for the nut to fit over. It’s easy just to cut a bit off with the Dremel, file and try again.

Torque tubes are in and all wiring is run so I should be able to start getting the top skins put on and riveted. After that I can start on the fuel tanks, though I still need the skin from TAF.

Flares are done… well if you look at the photo closely you’ll see one of the nuts is on backwards… DOH! so had to cut and redo.

The Pitot and AOA lines connected. For the connection to the 3/16″ aluminum tubes coming out of the pitot I used AN818-3D nuts and AN819-3D sleeves to connect to the AN816-3D nipple. The nipple connector is screwed into the push-on connector. It’s an 1/8 NPT type thread so I used Loctite 577 on it to seal it. The AN fitting doesn’t use and sealant. I had looked at ways to do this with using less adapters and couldn’t find a better way.

The control box mounted and electrical run. I’m using the regulated GAP26 so it has a control box to regulate the pitot temperature, there’s also a data cable that will go low when the pitot is up to temperature. I’m hoping that the regulated pitot will help a bit with reducing the current draw of the heater. I’ve heard that the load is a bit tight since you only have a 18A generator and 40A alternator, especially if the plane is well equipped for IFR flying. Also I’m not really using the internal generator for much so most of the load is on the alternator, but supposedly with both on the same bus it kind of shares the load a bit.

I originally had the main electrical feed lines connecting closer to the support channel near the middle of the wing (the control box has about 1.5 ft pig tails), but I figured that “when” the control needs to be replaced I stand a much better chance of getting the control box out and disconnected if the connections are closer to the control box and access panel.

I installed some sound proofing material in the pitot tube collar to keep the tubes and wires from moving around and rubbing on the collar.

Wide shot of the wiring and the pitot and AOA lines through the wing.

For leak testing I put a balloon over the pitot tube and then connect the AOA and pitot lines together with a “T”. I used the extra hose off the “T” to plow in compressed air until the balloon in inflated. I made a few markings on the balloon every inch so I could see if the balloon deflated. I checked each join in the lines with soapy water and didn’t find any issues. I let this all sit for about 20 minutes and saw deflation of the balloon markings so I’m going to deem it leak free.

And Now For Something Completely Different… Partial Panel

I’m kind of excited about this. While I was thinking about how to lay out my panel I had an idea. Rather than drill holes in the panel for each switch it might be more flexible to come up with a removable panel that the individual switch could go into and then just mount that into the main panel. This has quite a few benefits. One is the labels can be etched rather than silkscreened (since I’m using a carbon fiber overlay you can’t really etch that) also I can change buttons or possibly add a button or two later on if needed without messing with the main instrument panel. And lastly I think it will look kind of cool. It’s still an idea, but something I think will work out well.

So with that I decided to design and order the main switch panel. I’ll also have one for the alternator and battery switches on the right side of the panel, but I wanted to see how this one came out. I ordered it from a company called Front Panel. They have software that allows you to design the panel and then submit it to them. It only took a week for them to produce the panel (and could have been expedited if I paid more) and only cost around $70 (plus shipping). It’s surprising actuate. Everything seems to fit perfect.

So here’s what I got in the package… I was most impressed by the gummy bears 🙂 Seriously though the quality is great and the accuracy to what I specified in the software is incredible. All the labels are etched and filled so they won’t rub off.

Here’s the panel populated with the switches and a 5A breaker for the main fuel pump. Even the Sling logo came out awesome

Fuel Tank Jigs

I spent a few hours today building the jigs for the fuel tanks. I’m still waiting on the left fuel tank skin from TAF so I can’t build the tanks yet, but I should be able to get started with assembling a the fuel level and drain components on the ribs. I’ve been contemplating alodining all the fuel tank parts since some will not be primed (the surfaces that are expose to fuel). I will probably spray the other su5faces with primer after the tanks are assembled. So I’m wondering if it’s really worth the effort.

I’m also having a bit of a storage issue. I built a wing dolly (which I’ll post about later), but there’s not that much room in the garage to store the wings. I ended up reorganizing the garage so that the front of the plane faces in towards the back wall (rather than the garage door) so that I have more room towards the garage door side. I also was able to tempoarily put on the canopy doors because the garage door isn’t above the canopy in that area. This helps free up some space and I can also mount the hydraulic lifts for the doors.

I still have to finish up the left wing so I may try to get that done first before anything else. The weather is still really nice here in CA, but I’m sure it will start getting more windy and rainy soon and I don’t want to try to be building the wings and having to deal with that. The right wing is mostly finished so I want to try to get that into the garage this week.

The fuel tank jigs are finished, now I just need the left skin and the sealant and I can do the tanks. The jigs went together pretty quick. I used some left over plywood and had to purchase 2 2×3’s for the cross bar. I also did a test fit of all the ribs and Z channels for the right tank.

Right Wing Top Skins

Time: 13.5 hrs

Wow it’s been a few weeks since I posted. In that time I prepped and primed all of the top skins for both wings. I started with installing the skins on the right wing because it’s the easiest in that it doesn’t have the pitot tube. I finished up the wiring and double checked that everything was riveted on the wing structure. I also tested the wiring for continuity, just to make sure there were no breaks or shorts (you never know). I installed the short torque tubes for the flaps and ailerons and the long tub for the ailerons that runs to the fuselage. For the long tube I had to cut a hole in the wing jig so I could pass it into the ribs.

After everything looked good I clecoed the 2 main top skins on. I had tried to also cleo the leading edge skin, but I found that it pulled the wing in such a way that buckled the 2 main top skins so I decided the just get the 2 main skins riveted and do the leading edge skin after. I’m really happy with the way the top of the wing came out. There was one area of about 5-8 rivets the rear spar that needed to be elongated just a little bit to get the holes line up with the spar hole. It wasn’t a cleo pattern issue because all the hole before and after the area lined up fine.

Once the main skins were finished I clecoed  the leading edge and wing walk (wing root) skins. The wing walk skin lined up great. I think there was one hole that was a bit off. The leading edge skin was a real pain though. The tip part lined up fairly well, but as you moved towards the root it got out a bit. What helped was using clecos in every hole on the main spar and also I clecoed the ribs before clecoing the main spar. Still there were 2 holes toward the root end that just didn’t line up. One will get covered by the fuel tank skin.

Wire run to the landing and taxi lights. I used the lightening hole bracket that I purchased for the fuselage.

Had tp make a small how in the jig to get the long torque tube in. I could have waited until the wing was done, but I wanted to get this installed.

Aileron torque tubes installed

Flap torque tube installed

This rib is a bit wonky. I reriveted the front rivets that attaches it to the main spar, but it was still a bit bent. When the top skin went on it straightened out OK.

I installed an 1/8″ stainless steel rod to help support the strobe wire. It runs all the way to the wing tip and keeps the wire from hitting the bottom skin..

Celcos are in on the main skins and it’s ready to be riveted. Too late to rivet though so will wait until tomorrow.

All done. Happy with how it came out. Also the oil canning on the bottom of the wing seems to have gone away and no oil canning on the top.

I need to get started on the fuel tanks. I’m still waiting on the left tank skin from TAF since mine is really scratched (from shipping) and needs to be replaced. I guess I’ll start prepping the parts and maybe get some of the components installed on the ribs. I ordered the sealant and a SEMCO sealant gun so hopefully will have these in the next few days.