While the little blue pill is all the rage, sadly my problem isn’t as easy to cure. In my case, ED refers to “edge distance” and it’s the current bug-a-boo of my airplane building life. Assembling an airplane is simply a matter of holding many pieces of aluminum together so that they act as one big piece of aluminum. The things holding all this together are rivets, and rivets can only hold things together if they’ve got a tight grip on sturdy pieces of aluminum. If a rivet is too close to the edge of a part, that rivet can easily rip out when stressed, so maintaining sufficient “edge distance” is important.
In complying with the Service Bulletin 14-01-31, I’ve had to replace some parts and add new parts and in two specific cases my ED is a problem. Firstly, after buggering up the HS-814 Splice Angle, I bought a replacement only to find that it’s holes didn’t match the holes in the HS-814 I removed. The new piece’s holes were barely different, but that brought the whole ED issue out; there was insufficient distance between these relocated holes and the original holes already in place.
You can see that the holes in the silver piece on the left are staggered a bit while the holes drilled along the bottom edge in the right picture are aligned. The small blue sharpie marks adjacent to the two outer holes and the two inner holes along the bottom edge are where the new piece requires rivets. Def no good. It took a while, but I’ve just heard back from Van’s Aircraft that actually my kit wasn’t supplied with an HS-814 piece; it had to be fabricated from instructions and the instructions wanted all holes in a row! Hooray! Now I just have to make a new “old” part and I’m back in the game; no ED issues!
Oh, well, except for this one. Again, the SB I’m working on has modified parts of the existing Horizontal Stabilizer and added new parts, and things are getting pretty close. Two holes to be drilled as part of this procedure come very close to a Notch I was instructed to make in a part, so again: ED issue!
Just to the left of the “1” on the ruler in the picture on the left is a small blue circle, and it’s practically next to that nice rounded notch I made. The photo on the right shows the top and bottom notch with the small blue circle right next door! Again, this would normally be considered too close, but because this is a modification of an existing part, this closeness was unavoidable and while it looks bad, it’s considered “acceptable” in the circumstances of overall adding strength. Net – net it’s an improvement. While I’m generally smart, they’re very technically and specifically smart about such things. They have the physics and computer models to analyze such things and they say it’s OK, so on we go.
I feel like I’ve gotten all the answers I need to proceed, so back to the dungeon!