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BRENDAN'S WEB SITE
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Date:  2-21-2015
Number of Hours:  8.00
Manual Reference:  7-01 to 8-03
Brief Description:  FInished rudder, broke a part

We broke our first airplane part. Yup. The part in question is HS-18B, the AST (anti-servo tab) hinge.

Lessons learned: 1) Don't build when you're tired. 2) If you're going to break a part, make it a cheap one.

We had finished bulding the rudder skeleton before I took a trip to see my parents in Florida. Upon return, it was time to disassemble the rudder skeleton, because we can't rivet it - because we can't prime it - because it's too cold.

So, time to move on to Section 8, the anti-servo tab or AST. This component serves to increase the effort needed to move the stabilator (combined horizontal stabilizer and elevator), thereby improving pitch stability and feedback to the pilot.

This component really doesn't have a skeleton assembly as such. It does have ribs, which are riveted directly to the skin. Kevin and I decided all we would do was prepare parts. One such part is the anti-servo tab hinge. The process is to take two large sections of aluminum aircraft hinge (AN257) and separate them into four pieces (two AST hinge halves and two stabiliator hinge halves), each 32 1/2 inches long. The next step is to use HS-1223, the drill guide, to drill identical matching holes in a line across the bottom of each AST hinge half. And here's where things went wrong.

Getting the drill guide into place was a huge challenge. The only way to really secure it to the AST hinge half was to use pliers to force it - which defaced the part. Then, after drilling about a dozen holes, I realized that the holes were NOT aligned. Which meant the part was junk.

Fortunately, I was able to order replacement AN257 hinge material from Aircraft Spruce for about $15, counting shipping - it is not a bespoke part which would have to be ordered from Vans.

I have three un-drilled hinge half sections so I can try again. And when I do so, there are a couple of things I can do to make the process simpler. First, I will deburr the drill guide to make it fit into the part a little better. Second, after drilling the fir
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Happier times, building the rudder

Happier times, building the rudder

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