Accurately Locating Aft Fuselage Splice Plates (?)

[BobDz]

I started out life as a draftsman. As such there are things on the Sonex drawings that make me shudder. They are not mistakes, mistakes is much too strong of a word. I'll call them "idiosyncrasies".

One such idiosyncrasy occurs on F25, locating the longerons, upper splice plates, and lower splice plates. The very exact measurement (in 32nds) is to the Skin Bend Line. The only place that the Skin Bend Line exists accurately is on a CAD drawing. It does not exist in a workshop, as there are too many variables involved for that to be accurate - measurement error, bending error, etc, etc. In the drafting world we would have considered that a sin.

I was not 100% happy with one of my bends so I did not install the splice plates, giving me time to think about it ( ex girlfriend used to call it "retreating into my cave to sulk"). In the end, my 10 degree bends were perfectly fine - I'm just weird that way.

The solution to my "dilema" came on Detail E on F21. It shows That the Cross Tie Splice fits into the Upper Splice Plate. The Cross Tie Box CAN be located accurately because it is clecoed into accurately located pilot holes, so the Upper Splice Plate to longeron connection can also be accurately located. Problem solved.

The "accurate" location of the Lower Splice Plate is based on a note on Detail P, sheet F25 - "Forward-Aft alignment...". So I made a little jig out of a scrap of 1/16 × 1/2 aluminum, attached it to the Lower Splice with a 5d box nail (clecoe won't fit), match drilled the holes through the Forward Zee, clecoed, and match drilled the Splice to the Longeron. Another problem solved.

Now if I only had the right hand splice.

Yeah, I know I'm weird...

[SteveHoffman]

In the end, for me, the biggest issue in this area is locating the bolt holes so to allow for the nut installation so as not to interfere. At least two boltings became challenges for this reason. Think about where you will have room for a wrench or a socket.

[BobDz]

In the end, for me, the biggest issue in this area is locating the bolt holes so to allow for the nut installation so as not to interfere. At least two boltings became challenges for this reason. Think about where you will have room for a wrench or a socket.

Good advice Steve. The lower splice plate does come with pilot holes pre-drilled. Hope they too that into account.