I worked on the rear seat rib subassemblies over a few separate work sessions (page 26-5).
The first step has you flute the lower flanges of the outboard seat ribs to match to the corresponding holes in the curved bottom skin.
The fluting went well and the holes now align nicely.
I then match drilled the seat rib subassemblies from the previous section to the rear spar bulkhead assembly.
The order in the plans is a bit confusing to follow but it makes sense due to the overlapping outer ribs on the forward and rear side of the rear spar bulkhead.
I then dimpled the holes that attach the outboard seat rib subassembly to the rear spar. These take flush rivets that are then overlapped by the bulkhead side channels.
Next, I separated and deburred the seat belt attach lugs.
I did the same for the seat belt attach ribs.
I continued by deburring the rear seat ribs.
I then clecoed and match drilled the seal belt attach ribs and lugs to the ribs.
The rear seat ribs were then clecoed to the rear spar bulkhead and final drilled with a reamer.
At this stage I noticed that the F-1018 outboard rear seat ribs don’t align with the corresponding holes on the bottom skin and will need fluted similar to the F-1015A ribs. I searched the plans and can’t find any mention of this step. It clearly needs to happen before riveting so I checked the forums to be sure.
I’m glad I did as I found several mentions from other builders about omissions from the plans in this section.
For one, the plans do not make any mention of dimpling the holes in the web of the F-1015A ribs. The need to do so isn’t evident until pages 29-15 and 29-17 which identifies the holes that are dimpled in the side skins that correspond with the F-1015A ribs.
The F-1015B intercostals would also need to be dimpled to match the dimples in the ribs and skins. This is also not mentioned in the plans.
I also discovered that there are three more holes in the F-1018 ribs that get match drilled from the skin that will also need to be dimpled. This will be challenging later so I’ll probably sort that out now.
I decided to pause and do some more digging before proceeding. The plans have been pretty consistent so far and I have become a bit too comfortable in assuming that they are complete. There are omissions here that have been identified by other builders many years ago but the plans have never been updated. I’ll pass this info along to Van’s but it is hard to believe that they are not already aware of the shortcomings in this section.
On the plus side, the community saved me from making mistakes here that others had to resolve the hard way. A big thanks to everyone that has shared their lessons learned. These threads and blog posts have been particularly helpful: