Saturday, May 29, 2010

Hinge Nightmare


After the primer had dried over night I started the shop day by putting together the upper hinge assembly to finish the V-Stab.
Clecoed everything together and then rivetted the thing with AD4 rivets. After doing the three closest to the bearing I tried it to see if the bearing was still moving freely.... and: Damn! It got stiff again and would hardly move at all. The same problem I had before.
Thanks to the Van's Airforce website I had found out that the only reason why the bearing could lock up is pressure from the cage surrounding it. I checked the assembly again after drilling out the three rivets and I found a hint of primer on the inside of the assembly right where the bearing is sitting on. I could hardly believe that this little could have such a huge effect but I was getting desperate and in lieu of another clue I went on and scrapped off the little paint spray dust that got on it. Once it was all shiny on the milled surfaces again I put it back together started rivetting and .... you wouldn't believe, it worked!. I set all 5 rivets and the bearing was moving freely just like before when the hinge had been clecoed.
So, be careful with the milled surfaces and make sure they are totally plane and clean before wasting your time on it!
The image shows the finished upper hinge assembly next to the primed parts of the previous attempt (notice the thick layer of primer in the bearing cut outs) and also visible are the unmodified parts of the hinge as Van's sent me an extra set of parts.

Screwing on the hinge onto the V-Stab was a piece of cake after that. You'll see pictures of the whole assembly when I trial fitted the rudder spar to the V-Stab.

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