Finished Marking and Drilling Holes for the Patch Plate

Had to embark on the annual Dove hunting trip over the holiday, and this was really the first chance I ahve had to get back to the build since then. IN the previous post I mentioned that I was told to space out the perimeter holes in the patch plate so that they are no wider than the width of the holes of each #8 nut plate that would have been placed on the mounting bracket had I decided to stay with the original access hole and cover plate. WHile measuring out each side of the patch plate I realized that the holes would need to be placed a little closer together to evenly space them between the holes in each outer edge of the plate. The rule was to ensure that the gap between the holes not wider than 11/16ths of an inch, but they could be placed with a smaller gap between holes if necessary.

TO figure out the optimal spacing for the rivets on each side of the patch plate I used a rivet fan tool and tried to space each of the holes out as close to 11/16ths as possible. In reality most of the holes ended up being about 10/16ths apart from each other to allow for the 1/4 inch spacing of the end rivets along each side of the plate.

After marking each hole with a Sharpee I used the hole punch  to mark each hole location, clamped the plate to my drill board, and drilled all the holes with a #40 drill bit. Some of the hole locations were not spaced with the exact same gap. This was done to allow the symmetry of the rivet pattern to remain constant in a couple of places, i.e. the rivets along one particular line would be consistent with each other. This only occurred in a couple of places, so I think that the rivet line will still look like they are all evenly spaced.

After drilling each new hole in the patch plate, I deburred both sides of the hole, and then clecoed it back onto the subskin so that I could match drill the holes to the subskin. After that, I removed the patch plate from the subskin adn used my edge forming tool from Cleaveland Tools to put a slight bend along the edges of the patch plate. I did this as a result of some advice from my friend Mike Rettig, who had been through a similar exercise while building his RV-10 wings. He told me that if you don't  bend the edges then they do have a tendency to curl upward a bit when the dimples and then the rivets are set. The slight bend in each edge of the plate keeps the edges of bending upward too much. Had he not told me this I would have never done it, and would have experienced the problem for certain. So thanks for the advice Mike.I just need to remember to apply the same thing to the edges of the outer skin that surrounds the subskin to make sure that those edges stay flush as well.

This first pic is of the patch plate and new access panel all clecoed into place on the LE, and the new holes match drilled into the subskin:

This next pic shows the slight bend in each of the edges of the patch plate after using the edge forming tool

Next is the holes in the patch plate after removing it from the LE. This shows the spacing I used around the perimeter of the plate. Edge distance is 1/4 of an inch around the entire perimeter. Every single one of these holes will need to be dimpled, as will the holes in the subskin.

Notice the two holes in the left upper corner of the inboard side of the plate. Those two holes ended up really close together because I had already drilled one of the holes which was part of the designed mounting bracket for the NEW access panel. I may abandon this hole and have it filled or I may dimple both of them and rivet them. It will depend on the size of the dimple and if each dimpled hole will not interfere with the hole next to it. This is the only area of the new patch plate that I am uncomfortable with. I am totally satisfied with the rest of the hole patterns and placement. As stated previously, no additional rivets should be needed other than around the perimeter of the plate, since no specific compression of expansion forces are expected to be applied to this specific area of the skin, other than the same forces that will be applied to this entire section of the Le skin in between the attach points of the skin to each rib. IN effect, this area is simply being stiffened a bit to compensate for the loss of strength that may have occurred when I cut out the additional outer skin material for the mew access plate location.

Last is the pic of the subskin after the holes were match drilled and the patch plate was removed. I am mainly checking for rivet hole alignment here. not exactly perfect in a couple of spots, but close enough for me:

Next steps:
Removal of the LE and disassembly again for deburring various outer skin and subskin holes. (hopefully for the final time, but I doubt it).

Assessment of the wallowed out holes and final decision if I am going to need to use AN470 rivets to secure the outer skin to the rib and the subskin.

Dimpling all LE holes that will require dimples in all parts.

Countersinking all remaining LE skin attach holes to the Main wing spar flanges.

Make final decisions about the location of the cuts for the LE removal and rivet layout, as well as nut plate location determination for the removable LE section.