[dbhill916]

Hi All,

I fit my AST's to the horizontal stab yesterday, only to discover that there's about 1/8" difference in the trailing edges when the horns are bolted together. (Left is lower than right.) If I remove the bolt and align the trailing edges, they align with each other and the edges of the stabilator, but the holes in the control arms are off.

I'm (1) not sure where I could have messed up assembly, and (2) if the following repair is appropriate. I'm thinking that I can manually align the edges and match drill the holes with the next size up. This should align the trailing edges but at the cost of (minimally) offsetting the holes for the AST push rod assembly, but I believe that the bearing will easily accommodate the minimal discrepancy.

Any clues re: 1, and any comments (yea or nay) re: 2?

-dbh

 

[rgmwa]

I'd suggest you contact Van's for advice on this one. Sounds like you would need a different bearing for a larger diameter bolt. The other option is to remove the two end ribs and horns and order new ones. That's what I would do.

 

[alexe]

I have tried to reply to this thread twice and lost it each time thanks to fumble fingers. Anyway, I had a similar issue with the AST's. Luckily I had caught it prior to riveting the skins. Both left and right AST skins were distorted at the trailing edge; one inboard, the other outboard. I first thought it was incorrectly punched ribs, but proved that to be incorrect by swapping the ribs around. It turns out I had incorrectly bent skins. The first replacement set from Van's was just as bad as the original. When I called again, they said they had a new batch and to try a set of those. That time around the fit was much better, with only a tiny bit of distorsion present. I stuck with those and moved on.

I realize that replacing the skins at this point in your construction might be a major nose bleed, but it is probably the cleanest solution. On the other hand, your problem might be from a different cause, but it sure sounds the same as my issue. Call Van's tomorrow and see what they recommend.

 

[alexe]

David' Here is the picture of the distorted skins.

 

[J.Coles]

Hi David,

I think Alex might be onto it there. Although Vans say you don't need jigs the small flat parts can be assembled with a twist in them as I discovered. If this is the case I think you may be able to remove the rivets and reset. Take care with your flaperons as they are constructed in a similar fashion.

In fact after I had this problem I re levelled my work bench and took extra care to keep all of the structures straight and true when I started the riveting process.

Also the AST tab is very easy for your wife or friend or helper to twist and wreck the first time you go to move the plane around. So I got a lot of practice on this one.

Cheers

Julian 120316

 

[alexe]

Hi David,
I was curious to see if you found the cause of your AST alignment problem.

 

[dbhill916]

Not yet. It's on my list to work on, but I don't have any days off until Friday the 11th. I'll post my findings after I get back to the shop. Thanks for keeping track.