Tuesday, August 23, 2016

Finished riveting the left wing skin/rear spar - 5.5 hours

Big long night tonight for a weeknight. Since there are a handful of rivets I can't reach on my compact wingstand, I have to take the wing off the stand and lay it on a table. The easiest side is the inboard rib followed by the rear spar. I tackled these tonight, and I will leave the most outboard rib for last. I could try to do this myself but having a bucking partner would make it easier, so I'll just wait for help on that.

After I set up the pneumatic squeezer and got the right stool, I went to work on riveting the most inboard rib to the skin.

Next I began to chip away at the rear spar/skin. My method was to start putting in a rivet every second or third hole, and then began to remove clecos and then infill.






One of the things I noticed was that my rivets seemed to be slumping. Funny cause one of the things I do while squeezing is to watch the rivet 'bulge'. If the rivet is 'bulging' on both sides, then it is squeezing nice and straight. You can easily tell when it is being slumped as you can watch it happen....you can also stop squeezing and makes it easier to drill out and remove without stretching the hole. Of course these rivets were squeezing perfect, but they looked slumped to the left side.

When on closer examination I noticed that my dimples (from using the vice grip dimpler) put a halo ring on the bottom of the dimple that if shifted to the right, giving the illusion that the rivet shop head is not centered, when it actually is. Weird.

I then reached the point where I needed to upsize the rivet length as I was now into the doublers. Immediately I ran into headaches with the squeezer, so after drilling out the rivet I opted to buck the rivets. Well that went perfectly well. It was a slam dunk the whole way through.....

 
Until I reached the very last (inboard) rivet. Well...This rivet is the biggest pain to set in the entire build so far. The rivets and the thickness of the doubler above the hole make for a really tight area to buck. I managed to get 2/2 on the right wing set very nicely, but this wing I only got 1/2. The last one was just giving my absolute grief. I drilled it out about 4-5 times, to the point where I had to upsize it to an oops rivet. Which only makes the tight access situation worse. I tried everything I could including grinding down one of my tungsten bucking bars (crap!) In the end this is the result of the bucked oops rivet with the steel shoe bucking bar.
  

I decided not to mess with it anymore. I sent the pictures to an AME friend to ask his opinion, and called VANS in the morning. Both were in agreement that it is fine...not ideal...but fine. The consensus is that it is an ugly rivet...no doubt. but sometimes in the build one is going to run into a stubborn rivet that is just going to end up messy. So it's going to happen. the key is to minimize how often it happens. As tech support from VANS said - I don't see anything that worries me, but if you had 100 of those, then we need to talk.

Of course then next day...it never looks as bad as it did while you were in the situation. Sucks that it still happened, but in reality no plane is 100% perfect, and they fly just fine.

No comments:

Post a Comment