Horizontal Stabilizer Mounting Problem

17 Mar 2004 Horizontal Stabilizer Mounting Problem

Here’s the problem – I didn’t follow Van’s excellent advice and carefully look where I will be drilling from *both* sides. The result is that one angle bar was not as long as it was supposed to be, and therefore my hole is too close to the edge.

Here is a shot without the bolt. You can see there is not much left on the end. This is a shot from inside the turtledeck, facing up and back. It’s a strange angle, I know. Pretend you are laying on your back inside the back of the fuselage, with your head back, looking at about a 75 degree angle towards the tail. The bolts are little AN3s. Like everywhere else on the site, click on the pictures to make them bigger.

Here is a shot with the bolt in. Not really sure I can get a washer on there, even.

Van’s said that structurally, this will not be a problem. I spoke to “Ken”, and he said they had a problem with some QBs where this angle was not quite long enough, and they recommended that people be very careful drilling on the horizontal stabilizer. Sure wish I had looked under there more carefully! It’s pretty hard to see under there, it’s only possible with a light and a mirror. I have to say, even if I had looked I probably would not have caught the potential problem.

Now I have to decide if I should replace the angle, which will require drilling out the aft deck, and the angle. The problem is I’m not sure I can make it much better, since as you can see, the hole is *very* close to the longeron.

The best thing would be to re-drill the hole about half a bolt width inboard, but that’s not possible now, since I’d have to also rebuild the forward spar on the horizontal stabilizer. Don’t want do do that.

Ken said that the real strength of the horizontal stabilizer attachment comes from the longeron, not this angle. He said that replacing it was mainly just to make me feel better about it. What do you think?

Here’s how I fixed it: http://www.rv8.ch/article.php?story=20040606170101675Post