Prep for Final Assembly and Riveting of the LEFt wing LE

As mentioned previously, the next step was to remove the vinyl inside the LE skin that I have left on all this time to protect the metal. I do not prime the entire interior surface to try to save some weight. The epoxy primer overspray and cold temps have left this remaining blue vinyl in a state that is very difficult to remove. Here is one of the problem sections that I needed to remove:

I was not able to take my finger nail and lift up the edge to peel it away like I normally can. The primer hardened onto the metal next to the vinyl making this difficult. So what to do? I still need to remove this protective vinyl because if left on it can cause corrosion to occur by trapping moisture and debris between the vinyl and the metal. Unfortunately the vinyl only chips away and it won't peel off as one piece. 

After pondering this for a bit I remembered that I have a heat gun around here somewhere. I thought that maybe I can use that to heat up the glue on the back of the vinyl to at least soften it up a bit and see if that would allow it to separate from the metal easier. So I got this bad boy out and gave it a whirl:

After mucking with the setting son the gun and experimenting with how hot things could get, I finally came up with a procedure that involved holding the gun at a safe enough distance and heating up the entire surface of the vinyl as well as the edges until the vinyl softened up enough for me to peel it away. What I found out real quick is just how fast and how hot that heat gun can heat of the vinyl AND the metal. SO after figuring out how not to burn myself too much, this actually started to work pretty well:

Here is the sheet removed from the inside of the LE skin:

And here are some shots of what happens to some of the remnant primer 

It separates from the vinyl and rolls up into little flakes that have either a positive or negative charge that causes them to stick to the LE skin. After I got all the vinyl sections in between the ribs removed I had to use a shop vac to remove all the primer flakes.

The next task was to remove the red ink with the metal specification information. Normally isopropyl alcohol removes this very easily, but it has been baked on for so long that t was no longer doing a very good job, so I switched to using acetone, which worked very well. I was not too worried about wiping the acetone on some of the epoxy primer because that stuff, once hardened, is almost impervious to anything, and is very hard to remove with anything but acetone rubbed very deep and hard into the primer to soften it. What little acetone did come into contact with the primer evaporated away before it did any harm to the primer. I used paper towels and small dab of acetone to remove the red ink on the metal. Why remove this? Well some say it can lead to corrosion over time as well, but others say it doesn't harm anything. UP to now I have always removed it from the metal as part of the final assembly prep, so I did it here as well.

Once this was all done, it was time to final assemble the LE for what I hope will be the last time. the subskin and two inboard ribs were re-clecoed to the LE skin again, and the entire LE was placed back on the wing spar due to one thing I read in the instructions about making absolutely sure that the rear edges of each LE rib were exactly straight. The only way I knew how to ensure that was to re-cleco the LE back onto the wing spar again so that all the rear rib flanges were in alignment with the spar web, and then I can remove it again and start riveting the entore LE together. 

I also needed to put it back on the wing spar because I wanted to screw down the new removeable section using those new nutplates I just riveted to the subskin, so that I could check the actual "installed" fit of everything. As with everything else, I found out that after I screwed down the removeable section, all of ONE of my screws sat nice and flush to the skin exactly as planned. One of the screws was not laying flat on once end, suggesting that either my screw dimple or the hole or the nut plate was not properly oriented for the screw. It is not so bad that I feel that absolutely must fix it, but it may end up bugging me enough to the point where I am going to fix it anyway. This means removal of the subskin again to reset another nut plate, and of course it is one of the corner nut plate that are difficult to set.

I may actually try to set the new plate with everything mounted on the wing, but I am still debating that with my self. Here is the string of pics showing the part as originally envisioned, planned, and realized:

And finally, the same non-matching fit that I have been dealing with shows up once again after the part is screwed down onto the subskin, but the inboard side is quite flush and looks really good. I think I can still flush out the other side with the LE by applying a little fiberglass magic later on. 

Overall I am happy that it seems to have gone together pretty much how I envisioned it. Here are some final shots of the screws through the nutplates on the inside of the subskin: