SECTION 22: FLAP

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Special/New Tools/Supplies

Consider 3D-printing or buying a jig for countersinking the trailing edge wedges. There are a number of options available.
You need a #33 drill bit for this section (you may not have needed one so far)

How to tell the skins apart
- The skins have the rounded short side towards the fuselage. They are getting wider towards the rear of the plane to follow the fuselage getting narrower towards the tail.
- There are two skins that have 2 holes on the long edge about in the middle closer together. Those are the top skins. They have the same shape and same holes, but are still not quite identical as the punch direction of the holes is opposite. Probably better to put the side with the burs on the insides, then dimpling will just pronounce the punch deformation more.
- The remaining two skins are the bottom skins, do same selection for left / right wing by looking for the burs and keep them on the inside.

Step 3
- Be sure to read the bold caution text before starting this step. It may seem obvious, but a number of builders have accidentally drilled the FL-1007-R brackets when they shouldn't have at this point.
- If 1/4 inch brings the holes too close to the joggle, consider using a tiny bit less edge distance. There needs to be enough room for a 3/32 rivet head. Also the counter sink tool may touch the joggle's slope if the hole is tool far in.
Step 4: be sure to mirror this for the right flap. This is the only step you need to mirror until page 22-4.

Step 3
If you have a CNC machine, here are the files for the lightening holes of the spacer:
- Flapspacer.dxf
- Flapspacer.pdf

Step 2
The nose ribs don't have all holes pre-drilled. During this step, you will match-drill from the nose skin to the rib flanges to add them.
Step 5
- You can find a commercial or printable jig for countersinking the trailing edge
- Or, you can fabricate a shim for the cage of the countersink tool to rest on and then adjust the depth of the counter sink to account for the shim thickness. This is only explained in the RV-14 build manual which uses the same construction. See the RV-14 Flap build instructions, page 21-6 here.
  See also this FB thread.
Step 6
- Before dimpling, use an edge-forming tool on the nose skins since it's a lot harder to do after dimpling.
- Some of the holes might be difficult to dimple with a squeezer as the cutout on the opposite flange is too narrow, use the DRDT2 dimpling tool instead. The plunger is narrow enough to fit.
- When priming, don't prime the trailing edge wedge or the trailing edge of the two skins where the fuel tank sealant needs to adhere to.

Step 4
If your nose ribs look different then in the manual because yours don't have holes in some flange sections, please read page 22-5, step 2 where the ribs get match drilled to the holes in the nose skin.

Step 1
The two outermost ribs left and right have shared rivets between the nose rib and the main rib which need an offset rivet set. Consider using 4-4.5 instead of 4-4 rivets.
The other ribs can get squeezed, however at the one place where the nose and the main rib are adjacent, squeeze the main rib first, then the nose rib, else the main rib needs to be bucked because the nose rib is in the way.
Step 4: a 2-1/4" long Tungsten bucking bar is the perfect length to sit inside this flange (see picture below). If you tape it up enough you may not even really need to hold it in place as long as you can see that it is staying still. Also, watch out for areas where the skin isn't firm against the spar flange. You should be able to fix this by putting a slightly different angle on the rivet gun and hitting the rivet again. See red circle in the picture below.
Step 5: The plans aren't super clear about when you can/should rivet the two outer nose and main ribs. It seems it would be OK to do them at any time from this step onward except don't rivet the bottom skin until after the fuel tank sealant cures

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