Yearly Archives: 2013


Elevators 10 (4.0 hrs)

I did a lot in the past two days, and unfortunately did a poor job of record keeping.  I started out addressing and experimenting with my rudder rivet problem from my previous post.  I first tried to trim the AN470AD4-5 rivets just slightly to aleviate the cracking. This didn’t work.  Next I tried using a longer AN470AD4-6 rivet trimmed down to the -5 length.  This worked, but cutting all of the rivets would be a pain in the butt.  Jack Savage told me to heat them in the oven prior to riveting.  This also worked, but I don’t like unknowingly changing the properties of the metals.  Finally I set the rudder aside as Mike Bullock had agreed to meet me at the airport and give me some rivets he had.  Once I tried his rivets, they worked perfectly.  I’m convinced I have a bad batch of rivets… they seem extremely brittle.

While I had the rudder set aside, I worked on the elevators.  I back riveted all of the stiffeners to both skins.  Unfortunately I discovered I had not drilled, dimpled, or primed the trim reinforcement plate.  I caught up on that work as quickly as one can.  Unfortunately, after I set all of the rivets, I decided two rivets need a couple extra taps.  Not paying attention on the second rivet, it was slightly off the back riveting plate.  Its pretty nasty looking, but structurally ok.  I did my best to take as much of the dent out as possible.  This will be one area that will certainly have to have some touchup prior to paint!  Thank god it son the underneath!

Here’s the back riveting setup.20130526-221210.jpg

I had two rivets towards the trailing edge not come out perfectly.  I decided to drill them out.  20130526-221242.jpg

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Drilling them out went perfectly and the new rivets seated perfectly. 20130526-221345.jpg

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Here’s the trim reinforcement plate that I had totally skipped…20130526-221414.jpg

And two photos of my oops… 🙁20130526-221427.jpg

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Rudder 13 (0.75 hr)

I barely got anything done tonight due a new issue… cracking on the shop heads of the AN470 4-5 rivets.

The very first rivet I set, completely cracked, and didn’t even form a proper head.  I was perplexed because I knew I had squeezed it properly.  No worries, it was an excellent opportunity to use my new rivet removal tool!  I was able to set the proper drilling distance on my second adjustment, and the rivet head snapped off perfectly.  Certainly the easiest and best job I’ve ever done drilling out a rivet… so we’ll add that to my list of awesome tools.

I continued to rivet the rudder spar and spar reinforcement plates.  On the third plate I noticed another crack.  The crack was diagonal just like the first one, but not as severe as the head was properly formed.  I decided to inspect all the rivets I had just set.  Turns out about 8 of them show some type of cracking.  Time to stop and give some consideration to the problem.

I found some information on Van’s Airforce.  First this thread shows the EXACT problem I have.  Same rivet type, and same angular cracks.  I also referenced the mil-spec for the problem which states that “Cracks in driven heads (1) which fall with a circle concentric to 1.10 times the diameter of the nominal shank diameter, or (2) intersecting cracks, or (3) five or more cracks” are unacceptable.  Finally, I found this thread which provides some feedback given by Van’s support.  The majority of the time Van’s recommends leaving the rivet in place.

Its really hard to tell, even with a magnifying glass if the rivets are within spec.  There are a few that look worse than others, and I will likely drill them out.  More to follow.

Here’s the spar prior to any riveting. 20130521-200134.jpg

The very first rivet… completely cracked.20130521-200143.jpg

New rivet removal tool 🙂20130521-200150.jpg

Rivet in the process of being drilled out.  I had slight scaring from allowing the rivet remover to slip.  The damage was minimal.20130521-200157.jpg

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Here’s the best I photo I can get of one of the cracked rivets.  You can see the slight crack running diagonally in the side facing the camera.  No evidence of cracking on the top of the shop head. 20130521-200244.jpg

Here’s the diagram from the MILSPEC.20130521-200252.jpg


Rudder 12 (1.0 hr)

After the priming was complete, I started work on the rudder skeleton. I riveted the top rib to the counterweight skin, and prepared the counterweight by dimpling and countersinking. Finally I clecoed the rest of the frame together. It won’t be long until the rudder is complete.

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