Build Time: 1.0 Hour
Section 9IS/U – Page 03
Today I continued work on the RV-12iS spar box assembly, beginning with the spar cap spacers and then moving on to the upper and lower horn assemblies.
I started by clecoing the spar cap spacers to the spar ribs and spar caps, making sure everything was properly positioned and aligned. Once everything was in place, the spar caps, spar ribs, and spar cap spacers were riveted together.
With that portion complete, I moved on to the upper and lower horn assemblies. Following the instructions on page 9IS/U-03, I installed the horn doublers onto the upper and lower spar box assemblies and then positioned the upper and lower horns.
The #22 holes were final-drilled, and then I used a 12-inch-long #30 drill bit to match-drill the holes through the horns and the outboard horn attach angles. Because of the length of the drill bit and the geometry of the assembly, I took particular care to keep the drill bit perpendicular to the surface while drilling.
Next, I clecoed the inboard horn attach angles into position, clamped them securely, and match-drilled the holes. The cable attachment holes in the horns were then final-drilled to #12 as specified in the plans.
One of the most important details during this part of the build was keeping track of the exact orientation of the horn doublers. Before taking the assemblies apart, I carefully marked each doubler with its orientation so there would be no question about its proper position during final reinstallation.
Once all of the drilling was complete, the horn assemblies were disassembled and the holes were deburring and cleaned up in preparation for final assembly.
Overall, it was a productive hour in the shop. The spar box continues to come together, and today’s work was another one of those stages where careful drilling, alignment, and labeling should make final assembly much easier.
Total build time today: 1.0 hour
