New Access Panel Hole Created

With some careful planning and delicate surgery with a Dremel cutoff wheel, I was able to drill 4 individual 1/4 inch pilot holes on all 4 corners of the subskin where the new hole for the new access panel needs to go, and then I set out to cut out the new access panel hole. I had to remove different sections of clecos to allow 2-handed access with my flex shaft and cutoff wheel assembly as shown in the photo:

I mounted the actual Dremel tool on a bar clamp that I mounted on the work bench near the location on the wing where the cutting work needed to take place. You have to allow enough clearance for the bend radius of the flex shaft tool, so proper positioning of the tool was important.this setup allowed me to keep 2 hands on the flex shaft handle while carefully cutting along the previously drawn cut lines on the subskin.

It is very easy to watch these cutoff wheels suddenly develop a mind of their own and completely ruin in a split second whatever you are so painstakingly working on. So when accuracy is required, the key to maintain solid control of the tool with both hands to to go very slowly, and ensure that the tool is positioned comfortably and correctly to make the cutting as easy as possible. My other trick is to use a plunge cutting method instead of trying to cut the entire edge like a saw. This way you are cutting small sections of metal with the wheel, overlapping the previously cut section as you go. It only jumped on me once, and it did not jump very far since I had both hands on the tool and I was ready for it to do that, so I consider myself lucky once again.

Here is the result after cutting all 4 sides with the wheel. I would remove all interfering clecoes, test fit the tool and do a non-powered dry run to ensure the cut would go as planned, and then turn it on and cut one side, Then I would shut it off, re-position the clecoes, and do the next side, I did the left, bottom, right, and finally the top side. I cut just inside the drawn line to ensure that I did not cut any metal outside the lines, since space is tight as you can see, and the resulting cut line is very close to mounting surface for the nut plates.

And a close up of the part now "removed."

I guess I should also mention that to drill the 1/4 inch holes accurately on all 4 corners, I measured 1/8 inch from both sides of each corner, drew intersecting lines, and then used my hole punch to mark the 1/8 inch radius spot for the drill bit. Then I started each hole by manually turning the drill chuck to ensure that the bit was positioned correctly, and then I pulled the trigger on the air drill and finished drilling each hole.

The last pic for the evening shows clecoes now occupying the holes around the perimeter of what would have been the mounting flange of the pre-cut access panel hole that Van's created at the factory. (The one that I now have to fill back in since I am using the new one.). I decided to go ahead and drill and rivet these holes just to allow the subskin to support the LE outer skin in that area, since so much material has now been removed. I am still a little concerned about strength in this area, but I think the subskin provides more than adequate stiffening of the area, especially since the edges of the subskin rest over the tops of two LE ribs.

Next steps are to get the files out and do some more critical surgery to smooth out the edges of the new hole, and also to trim and final-form the odd shaped piece of metal that I had to cut to fill in the space from Van's old hole. Sure will be glad when this stuff is all done. The time suck for just this little thing has been enormous. I can only imagine what putting nut plates and screw holes in all the floor panels of the fuselage is going to be like when the times comes.

I also had a revelation today while at work. For some reason I had been thinking that I still had over one and one half weeks left before I would be leaving for Oshkosh. Then I looked at a calendar and realized that one week from today I will once again be on the road for the greatest aviation show on the planet. Very cool........

That's all for tonight.

KPR