Forward Bottom Skins

Time : 4 Hours

Today I start work on the forward bottom skins. I had several tasks at hand, besides finishing the edges of the three skins.
The first task was to trim the edge of where the key or access panel will be to make sure it cleared for the newly installed gear brackets and bolts. This Took some time putting the skin on, marking it, removing the skin, removing the material and return in the skin to the fuselage. The plans have you do the step earlier on however since my gear alignment moved aft I needed to readjust this trim.

The next task was to enlarge the 4 holes in the skins that will allow a socket to gain access to the AN4 bolts on the outboard wear plates.

I then deburred all the holes, enlarged the screw holes to a #19 drill bit and rolled the aft edge of the aft skin. I then grabbed my DRDT dimpling machine and dimpled all the required holes. The inside of the skins got scuffed, cleaned and primed as well.

I ran some errands and let the primer dry for an hour or so. When I returned I started the riveting process. Van’s has you put 2 blobs of blue RTV sealant in the space that is too narrow for a bucking bar to give some skin support on the aft end of the aft bottom skin.

The plans have you rivet the aft ribs first by lifting the outboard edge of the skin while the rib/skin joint is clecko’d. It’s a tight fit but you can do it with a very thin bucking bar. Next you are supposed to remove the forward crossmember as this will give you access to rivet the aft crossmember. Well since I created my battery box on the angled support I had riveted the two nut plates to it, oops. So I could either drill all those out or I could use blind rivets on the 9 holes that I could not access on the forward crossmember. I chose the later! So that meant that I had very limited access to rivet the aft crossmember by lifting a small flap of the skin. That was tough but I was able to get all the rivets done. I then drilled the rivets that would get the blind rivets to a #34. I calculated the thickness and it was at the top range of my MK-319-BS flush rivets so that worked well.

Thats where I stopped for today as I need a bucking partner to get the aft edge of the skin rivets as well as the forward edge of the forward cross member. The outboard edges of that cross member get covered by the two forward skins and you would have no bucking bar access if you went ahead of this step. After I get help I will be able to rivet the two forward skins and the cooling ramp. Another good day in the Hangar oh and today marks the crossing of the 1000 hour mark!

Mounting the Gear Legs

Time: 6 Hours

My buddy Glen stopped by yesterday to give me a hand at match drilling the gear inboard attach brackets. The inboard end of the gear legs have a 7/16″ hole already drilled in them. You use that hole as a guide to drill the bracket. After that hole is complete you can use the newly created bracket hole to match drill the inboard wear plate. After cleaning up the new holes we placed the gear leg, inboard wear plate, inboard bracket and the outboard wear plate into position and placed the bolt in the holes.

We repeated the process for the other gear leg.

With the legs in place and the bolts hand tightened I started the process of aligning up the legs. You have two jobs when lining up the gear. The first is to make the gear leg faces line up and be square. To do this you run a plumb bob at the very outboard edge on the face/fwd side. Then you run another plumb bob somewhere in the middle, I did 8″ inboard of the first line. Now you can run a taught string on the ground and adjust the legs so all 4 plumb lines hit the string on the ground. This tells you that you have the two faces square.

Now you need to make the squared faces perpendicular to the centerline of the fuselage. To do this I dropped a plumb bob in the tooling hole in the aft end of the fuselage. I then taped two tape measures to the ground and put the V of the two right at the plumb line so that each tape measure was at the 12″ mark. I then took the other end to the outboard gear leg plumb bobs and made those dimensions equal.

The last tweak is to make the space between the outboard edge of the outboard wear plate 3/16″ inboard of the longeron edge.

I then got to drilling, first with the forward 3/8″ hole of the outboard bracket. I placed a bolt in that hole and drilled the aft hole. I used a lot of Boelube and a slow drill speed. Once those two holes are complete I did the inboard 5/16″ holes. For the next two holes I hit the 1/4″ inboard wear plate holes but I had to drill up through the gear weldament and through the wear plate. That wasn’t fun drilling up underneath the fuselage. The last two holes are the 1/4″ wear plate holes on the outboard ends. So that’s 9 holes per gear leg that needed drilling. I repeated the process on the opposite side. That took a couple of hours as I was taking my time to make sure all alignment was kept in place.

That’s where I called it a day in the Hangar. I feel really good at finishing that task. I had been studying the plans and reading several builders blogs to make sure I understood the plans. On to the forward bottom skins.

Fuselage Skins Done

Time: 8 Hours

I got early this morning and finished up the riveting the aft end of the fuselage skins. My buddy Glen arrived late morning after I was finished with that task and help me flip the fuselage upside down on a pair of sawhorses, man this thing is starting to gain weight. We took our time and planed the flip making sure the height was right with my adjustable sawhorses. I wanted the height to good for me sitting on my rolling stool and good arms reach will inside.

From there we finished all of the remaining fuselage rivets on the bottoms and sides of the skins. It took us a couple hours but we worked pretty well together and all of the rivets turned out great. Every skin overlap was tight and no puckering. I did have a little oil-canning on the bottom aft skin behind the aft baggage ribs. This is a known issue for some builders and probably happened to me since I riveted the sides first. I will put a light weight angle on the inside of that skin to reinforce it.

After Glen left I finished up a few tasks like riveting the gussets to the bulkheads now that the skins are riveted. A couple other items I took care of like tightening the castle nuts on the rudder pedals and put in the cotter pins in place. I also fitted the two David Hoffman LED cockpit lights that I bought from Van’s into the forward roll bar angles. The holes are close to the edges of the hole but not a big deal as its steel.

I decided today to leave the fuselage in the upside down position. This is due to how hard it is to turn it over with just two people, putting the fuselage a greater risk every time we roll it. There is only a few more tasks that need to be done before I would need to roll it back upside down to do the landing gear installation. So I’m going to wait for those and do the landing gear installation next after I study and review the plans, as this is a critical task. My work schedule is quite busy over the next three weeks so I may have a break before finishing that gear installation. Until then I will take care of all the little tasks that remain now that I have the skins finished. For now I’m just going to enjoy the fact that all those clecko’s are removed! Another big mile stone in the Hangar!

More Fuselage Riveting

Time: 6 Hours

After attending my aviation department staff meeting today I got right back to the Hangar to continue the roll I was on riveting. I needed to finish up a couple of stiffeners on the forward skins and then I could move aft working on the mid side skins and aft tail skins. I worked with my bucking bar/gun and pneumatic squeezer. I didn’t take any pictures during the process as I was on a roll. Here are some photos of the almost finished product. I still need to hit the last third of the tail cone from the middle down. Obviously I couldn’t do the bottom skins, but I will get those tomorrow when my buddy Glen helps me out.

Tomorrow morning we will flip this fuselage upside down and place on a couple sawhorses. This will make it easier to read it the bottom skins, as one of us will sit on a stool and buck from the inside and the other will rivet from the outside. Another fun day in the hanger, but boys my back sore! I have bruises on both of my upper arms from leaning and wrapping over the top of the sides.

Fuselage Riveting

Time: 6 Hours

Today I started riveting the fuselage back together. First thing to do was to put the forward skins in place, along with the spacer’s, the gear tower box plate’s and the auxiliary longeron’s. The plans call one step prior to putting the forward skins in place, some ProSealing. They tell you to put a bead of sealer right at the corner edge of the firewall, presumably to prevent fumes and such from the engine area migrating into the cabin. I decided to skip this step and take care of it later. I will eventually fill the notches on the firewall from the forward side and run a bead of sealer on the aft side of the firewall where it meets the skin. It’s a tight space but with a long nozzle and my Semco ProSeal gun I should be able to do it pretty easy. The reason for all this was cleanliness and I didn’t want to create a bulge under the skin. ProSeal is thick and the fact that you don’t rivet this firewall flange until later means that you only use Cleco’s at this time. Cleco’s are not strong enough to properly squeeze the skins together with ProSeal between them causing the bulge.

Once those your place you start with four rivets at the bottom of the skin by the wing spar. They are in a tight spot where a bucking bar won’t fit so you use blind rivets.

Here is a view of both skins and parts all in place before riveting.

Once I have the skins in place I started the riveting process working forward to aft. I carefully studied the plans for all the different rivet call outs, in the holes that will be riveted later. I used my tungsten bucking bar and both of my rivet guns. For the upper longeron in the rivets around the wing spar I was able to use my pneumatics squeezer. I only had to drill out one rivet, not too bad.

It was getting late so I called it a night, I have a few more rivets left in the forward skins. Next I will start on the middle skins and work my way back on the tailcone. Saturday my buddy Glen is coming over to help me read at the bottom skins and the other rivetsthat I can’t reach.