Stephan's Sonex #1627 Builder's Log

I riveted the forward spar and main spar assemblies. I also installed the AN3 bolts. The thread on the bolts did not extend far enough down, requiring a total of 3 washers instead of the 2 the plans call for. I did not get a chance to complete the riveting of the vertical stablizer.

I did more work on the vertical stabilizer today. I spent time fitting the skins and making sure that all the holes lined up on the center of the various ribs. I then pilot drilled all the holes and cleco-ed everything together and then up-drilled to #30.

The SNX-T12-10 clip that I had previously fabricated did not appear to cause the tip rib to be positioned correctly for the holes in the skin. I checked the measurements of the clip and it was all correct. If I used the clip, the holes would be too close to the inside edge of the rib. I contemplated putting the clip inside the rib instead of on top of the rib. This would have moved the rib up and lined up the holes with the center of the rib better. However, this is not standard aircraft construction practice, so I decided to fabricate a new clip that had a longer flange so that I could push the clip up more. 

I attached the rudder hinge and drilled all the pilot holes. I then up-drilled to #30 and cleco-ed everything togeher. Once I had updrilled everything, I took everything apart and deburred, cleaned and primed all the parts. Next time, I'm going to rivet everything together.

I worked on fitting of the vertical stablizer assembly and skins. I laid out the whole stablizer on a flat surface and then clamped everything together. I then drilled all the holes for the various attachment clips. I have not yet drilled the SNX-T10-04 (tip rib), because I want to make sure that the holes in the skin are going to line up with the forward spar assmebly and if I drilled the tip rib and fastened it, it would make lining things up more difficult.

I was surprised how well overall the holes lined up with the center lines I had drawn on the various ribs. I'm going to have to figure out what I'm going to do with the 4 bad holes I drilled in the main spar assembly before I go any further.

I contacted Kerry at Sonex and provided him with a picture of the problem. He indicated "...the only thing we would ask you to do is add one additional rivet between each of the errant hole locations. Even that is most likely unneeded but it is insurance against the unlikely possibility of those holes tearing out.". In other words, a straightforwrd fix and I don't have to redo the part. Excellent!

I completed the rudder today. This involved deburring the edges and the #30 holes of the ribs as well as skins, and of course, cleaning and priming the parts. The skins were primed where it comes into contact with the ribs.

I riveted the long side of the rudder, so it would still be easy to open up the skins for the pre-cover inspection. This is required for Canadian amateur built aircraft (click here for details). The other half of the rudder will remain cleco-ed until the pre-cover inspection has been completed.

The rivets on the rudder control horn were tricky. There were 4 rivets that had interference from the adjacent rivets in the rib. I checked the plans and it appears that this is by design. It would have been better if the top holes were slightly offset so this wouldn't have been an issue. I used a hand riveter to initially pull the rivet until I could push the head flush with the skin, after that, I pulled the rivet with the pneumatic riveter.

I completed the installation of the rudder hinge and the rudder control horn. The hinge installation was a little bit tedious because the supplied piano hinge was bent for shipment causing a wave pattern along the flat edge of the hinge. I put the flat portion of the hinge between two metal rulers and squeezed it with my vice to make it as flat as possible.

I used a piece of 0.060" sheet metal as a spacer for the hinge because that is all I had available. This is slightly larger than the 0.057" that the plans call for, but I don't think it's going to matter.I used a wooden block behind the skin to put counter pressure for the drill. I first drilled the edges then the centre and then alternated between left and right outer edge until all holes were drilled.

The rudder control horn was equally tedious. I first drilled the holes in the skin as per the plans and then marked up the centre line of the flanges on the control horn and lined it up with the holes in the skin. There was a significant gap near one of the edges, but I managed to eliminate it by receeding the control horn slightly into the skin. This caused some holes to be closer to the inside edge of the control horn, but I determined that there was still enough clearance for the rivet.