This is the flap bottom skin. At first I've fitted the inner ribs. These are full ribs, no stiffners as on the ailerons. The flaps will hang down into the slipstream by 40 degrees, so they have to be stronger than the ailerons. Lay a staight edge over all ribs, I had to rebent the inner ones, the were slightly higher than the outside ones.
The next step is to drill the spar to the inner ribs. As you can see, there is a double surface on my workbench. You jig the flaps on the bench, so it is very important, that the workbench is level. There are some stories about twisted flaps, but mine came out straight. You will find the correct drilling sequence in the book '21 years of RVator'. The manual said that the flaps are most easily to build movable surfaces. I think the ailerons are. So be sure the flap skin is firmly down on your level workbench, before you drill anything. I should have had my angle-drill at this time, but I had to take the long drillbit instead. Meanwhile I bought a CP(Desoutter) pneumatic one at EBAY's for a very good price: 55 Euros and as-good-as-new!
The flap spars inboard end. This is the reinforcement bracket. The pushrod for the flap will be connected to this thing later. There is no straight edge here, and it takes some time to make all the bars and plates and angles fit each other. Be careful when you rivet these parts together, there is only one sequence that will allow you to reach all rivets. I've taken care of that with the first flap, but why not with the second one? You see the row of clecoes on the right? I riveted that row too early and was'nt able to reach the rivets that go into the rib/top skin. So I had to drill them out again. Too late? Too much liquid building assistance?
Another shot of that thing. There is no straight edge on it....
You can't read it, but that tag on the drill says: Your life jacket is under your seat ;o)

At first I was worried about the fly-cutter, but if you clamp down the spars, it works great. Thank you, Günther, for the express delivery of that cutter. (I don't have a fly-cutter, and Günther, the former owner of this kit, sent his one.)
It's worth the affort!
This is the flap barce. It is stepped down to clear the rear spar reinforcings at the root side of it. This brace is the achilles heel of the flap position, so drill it only to the wings rear skin at this time. Once the partly assambled flap is installed, you can shift it until the lines of flap and aileron match, then you can drill some holes to fix iton the spar. The piano hinge is missing here at this time.
Here you see the flap without the top skin attached to the rear main skin with that piano hinge.
This is how it look from behind. The little pieces of aluminum help to alingn the flap and aileron skin. Now you can fix the inner aileron attachment arm and the outer position of the flap brace by running a taut thread from outer aileron top to inner flap top, after you've sliped over the flaps top skin.
The flap top skin is in place, a taut thread runs on top of the flap and aileron to assure both run in line and the thread runs around the tooling hole bolts, so you know the flap is in it's neutral position. Now the flaps top skin can be fixed by drilling 2 holes right into the outer ribs.
The flap was clamped down to the workbench everytime a hole was drilled, it came out with no warpage at all.
The top skin runs around the trailing edge of the flap and ends some inches after that. This row of rivets is hard to set, because if you would bounce off the head too much, there would be a ding in the top skin, it's thight fit.
Once the flap is removed from the wing, riveted together and installed again, this is how it looks. One height, one level.
This is the inner aileron attachment arm (thats not the name the plans call it, but now you know what I mean), rivited to the rear spar after all this. You can see the hinge pin runs right through that arm. this is not per plans, but other wise you would have to cut the pin to insert it from the middle of the hinge, and it can be done this way if aileron is full down. It's a good point to secure the pin, too. Aileron gap seal on the left, this looks different on actual kits, similar to the flap brace.
The aileron pushrod.
The row of rivets where the aileron gap seal is rivited to the wings top main skin is hard to reach with a bucking bar, as you can see.
...but it works.
Setting the aileron travel the caveman way. It has to be 25-30 deg. up and I disliked the idea to buy an expensive digital tool for that. There is a piece of plywood, marked with 25 an 30 degree lines clamped to jig at the turning point of the aileron. The marker is a long drillbit inserted into the aileron bracket. Simply set the bit parallel to the line and clamp on the control stop. Meanwhile I've controlled it with a digital angle I could borrow, an it's 29,8 degrees on the left and 30,2 on the right. Sufficient, eh?
Now it's time to finally close the wing, but at first I installed the pitot line and the plastic guard for the wire that runs to the wingtip position light. If you plan to install that tubing, drill the holes when you straighten all the ribs. It's hard to do once the ribs are installed.
Tanks are primed and fuel senders installed.
Pressure testing of the tank. Any children around? You need some baloons and that bubblewater (whats that in english??) to find a leak. Left tank: Pressure gone after 15 minutes, right tank the same. ''*"!?'*

Another baloon, control all fittings, same procedure, same result...

Seal the baloon connection, seal the green hose, same result.

Hey, Evan, what's that? No, no, watch the next image ;o)
The fuel cap! You see that bubble under the yellow tape?

Puh!

After this fix: Both baloons under pressure for 24 hours, give me AVGAS!
Done!