Saturday, June 12, 2010

Stepping through the steps steps

There are more steps to installing these steps than.... ah, I got nuthin'. I just wanted to play with the homonym.

The most notable thing about the angle brackets that I trimmed and primed before is that only one of the two flanges on each has holes drilled in it. This is, as I have learned, a strong indication that there will be match drilling in my near future. That future is today! The brackets get clecoed into place on the back side of the bulkhead:

Then on to the match drilling, which as we all know means "the simultaneous creation of two holes that will not align."

There are nine holes to be drilled on each side of the plane - a column of five and a column of four. The bottom hole of the outside column then gets final drilled to 1/4". Having already been drilled to #30, the hole is easily expanded to 1/4". A bolt is then fed through the lower bolt hole on the step and through the 1/4" hole. The step is then pivoted to a position that makes the actual step part of the bigger step piece horizontal with the ground while still  keeping the upper end of the step piece below the upper edge of the bulkhead. It's easier to understand with this picture:

I clamped it into place in order to hold it still while I drilled another 1/4" hole through the upper bolt hole and through the bulkhead:

Because I hadn't led off with a nice #30 hole, it was a real chore to get the 1/4" hole drilled.

With all of the holes drilled, the steps are in what will eventually be their permanent positions.

The steps aren't actually bolted on yet, but not because they would just be in the way for the remainder of the build (although that is certainly true) but because there are no nutplates behind the bolt holes yet. Everything gets taken apart again at this point, up to and including the bulkhead which was only being held on with clecos. Four aluminum braces with a nutplate each are positioned by installing a bolt through them to hold them in place while they are match drilled. Fortunately I've been double- and triple-checking things lately, so I noticed a problem before committing to an irrevocable drilling operation:


All of the bolting and unbolting and moving stuff around was pretty rough on the bulkhead and the braces so I gave everything another coat of primer. Make sure you mark the location of all of the pieces before you remove them - they're match drilled, but things will go much smoother if you put everything back in the same place you found it.

Once the primer is dry, all of that stuff will get riveted onto the fuselage. 

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