Wing Ribs - Complete

10/22/2011
Total time: 439.0
Hours: 19.7
Wing Ribs: 34.7


The wing ribs are done!  It was all fairly straightforward.  The big issue occurred when I riveted the aluminum angle to the torque tube bracket.  The holes in the rib's web did not match the holes in the angle.  This was a mystery since they were match drilled and should have fit perfectly.  It was late when I discovered this problem and assumed it was because I had forgotten to install the spacers between the bracket ends when I did the match drilling.  ....  I even ordered new angle from Van's.  But when I drilled out the angle from the brackets, I realized that I had installed the angle backwards from how it was match drilled.  Now, I mark things meticulously to prevent this kind of thing from happening.  But somehow, I mixed up what my marking meant and (on both wings) installed the angle backwards.  Once I realized what really had happened it was no issue really – aside from the fact that I mangled several holes removing those rivets.  When the back piece is relatively thin metal and not firmly fixed to some other structure, it's almost impossible (for me at least) to drill out rivets without damaging the holes.  So, on almost every hole, I had to drill out to #21 and use 5/32 rivets.  No big deal really.  Just annoying.


The other issue was when I riveted the ribs to the left spar.  For some reason I had a bear of a time installing those rivets correctly.  The shop heads were all fine, but I kept bouncing the rivet gun and mangling the rivet heads.  Then let me tell you, drilling out rivets with mangled heads is haaaard.  Half the head breaks off and the other half is then extremely difficult to deal with.  In total, there were 10 rivets out of 77 rivets that I had to drill out and several others than don't look great, but I felt were safe.  And of those which were reinstalled, several had to go up to 5/32 because of damaged holes.  That's about 13% replacement for those who care and that's a lot.  I tried everything to correct the problem: reduce the pressure, use different heads on the rivet gun, hold the rivet gun lefty or righty.  Seemingly, I could do nothing to get consistently good rivets.  In the end, I spent four hours riveting and drilling and re-riveting the ribs on the left wing spar.

The next morning, I was fresh and ready to try again.  I changed two things. First, I got Scott to help (I wish I had a picture of him helping, but forgot to take one).  And second, I decided to drive all the rivets from the forward side of the spar.  The night before I drove from the aft side and I think the constant interference from the ribs themselves against my hand or the rivet gun didn't help.  I drove and Scott bucked.  All 77 rivets went in without a single problem and every one looks perfect on top of that.  The whole job with Scott's help took less than 30 minutes.  Amazing what a fresh day, a fresh perspective, and a second pair of hands can do.


Next up: The rear spar.


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