The dreaded rudder trailing edge

Rivet count: 349

Just got to work half a day today… my wife and I went to the art auction (the interest for loans at the bank of marital bliss is expensive!) to buy some art and get a nice Persian rug.  That went pretty well (I liked what we bought), but it took up the whole afternoon.  Still, I had enough time in the morning to be productive.

I started the day by heading off to the Home Depot Aviation Supply store.  I needed to find a replacement chuck key for the one I misplaced at the shop.  I still don’t have a clue where it might be, but I didn’t want to lose the better part of a short day looking for it.  I found a nice (cheap) Ryobi one.  I added a big triangle of orange safety tape so it should be easy to spot.  I also needed some RTV sealant for the rudder stiffeners and some epoxy putty for a home project, so it was worth the early morning trip.

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I picked up where I left off… countersinking the trailing edge wedge.  Lots of holes to do.  Both sides!  I created an awful lot of aluminum “pixie dust”  The conventional wisdom is to be careful not to countersink these too deep or you will ruin the trailing edge (and get a bend).   I’m not sure what “too deep” is, but a 3/32″ rivet fit in pretty much flush. You can see the new chuck key in the photo above as well.

The instructions call for using double sided tape to hold everything together while you rivet.  People online had mixed reports, but it was more negative than positive, so I opted to use the older “glue and clamp” method. I prepped the edge and wedge by scuffing with some sandpaper and then cleaning with acetone.  I wanted the glue to really stick.

The conventional wisdom also calls for clecoing the edge to a piece of angle to keep it straight whilst waiting for the epoxy to cure.  I wanted to make sure I had some angle that would not flex, so I got some 1/4″ x 1.5 inch stock from OnlineMetals. It is very stiff, but it was a horror to drill.  I didn’t want to dull my aviation jobber bit, so I started with a bit from my cheapo Home Depot bit set.  It lasted 10 holes and then broke off.  I finished the rest with my #40 bit.  This was pretty time consuming and it used a lot of compressor air.  Definitely called for hearing protection!  Then I ran a belt sander across the holes to make sure the whole thing was flat and finished with a piece of painters tape on top.  I didn’t want to bond the rudder to the angle permanently!

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Finally, with everything prepped, it was time to dive in. I went to mix up a batch of epoxy to glue the wedge.  But the epoxy had hardened in the tube.  I could get catalyst out, but not the epoxy base.  Luckily, there is a little hardware store at the bottom of the hill.  I shot down there and bought old fashioned epoxy with the help of the wizened old guy behind the counter.  I like mixing the epoxy.  I reminds me of working with my Dad building his boat.

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The next step looks like it requires six hands… and in fact the instructions suggest you get a helper.  A lot of people said that they did it solo, so I dove in.  Here, I use a piece of painter’s tape to curl back the left rudder skin while I pop-rivet the stiffeners and sheer clips in place.

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This was a bit awkward and at times messy since I was also advancing a thin line of epoxy cement on top of the wedge as I went.  I didn’t want to get any pillowing between rivets, so I tried to used the epoxy sparingly.  My hands were busy (and often goopy), so not too many pictures. Not show is the blob of RTV at the trailing edge of each rib.  It is supposed to help keep the edges from vibrating and cracking. Here’s a picture of the whole shebang clecoed up and hardening.  The one missing cleco is the hole where I broke off the drill bit.  The edge is nice and tight and uniform.  We’ll see how the riveting goes next!

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Next up… riveting the trailing edge (double flush technique) and assembling the counterbalance.



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