Seat Substructure/Center Section Work

Time: 8 Hours

I got an early start today in the Hangar so I could get some work done before our quarterly pilot and staff meeting this afternoon. First up was to scuff the bottom flanges of all the seat ribs. I try to do this before dimpling as the raised dimples tear apart the scotch-brite pads if I do it after. It just happened that I remembered to do it first this time. I then grabbed the pneumatic squeezer and dimpled all the flange holes.

IMG_4166.JPGNext up was to dimple the bottom skins. There are several rows that you don’t dimple at this time. I marked those with a red sharpie and grabbed my DRDT simpler and went to town.


IMG_4164.JPGWith the dimpling done it was on to scuffing and cleaning all the parts. That was followed by priming.

IMG_4169-0.JPGThere are a couple parts of this substructure that will be slightly visible in the cockpit. So I will finish paint them. Before I do I had to rivet the seat belt attach lugs together.


IMG_4170.JPGNow that I had all the seat substructure primed and painted I went back to the center section as the paint has had a week to cure. The one thing about the Rustoleum is that it can be worked with after around 5 days but it can be chipped still to get a real cure you need a month or so and it seems like it becomes hard as a rock. So still try to be careful as I can be when working with the painted pieces but I know I will have some touch up to do. I borrowed some bolts from my friend Glen that he used for this task. They have the treads ground off so you don’t damage the close tolerance holes of the spar center bars. They help align everything for riveting


IMG_4174.JPGI was able to get about half of the rivets with the pneumatic squeezer and did the others with gun and bucking bar.


IMG_4175.JPGThat was the forward half I then moved on to the aft half. It was the same process as the forward except this side has the seat ramp and supports. I had to buck most of these as the squeezer wouldn’t reach.


IMG_4177.JPGNow was the time to mate the 2 halves together and match drill the top flanges. Van’s also instructs you to create a wood spacer that goes between the 2 halves to act as the wing spar. I have read several different builders websites on different spacers. My friend used 1/4″ bolts with several nuts and washers. I decided to try the PVC route. The space is called out in the plans as 1 7/16″ or 1.438″. I measured and cut the 3/4″ PVC to exactly 1.438″.


IMG_4179.JPGOnce the spacers were in I match drilled all the holes followed by countersinking the nutplate holes. There were 3 extra holes in the bottom flange that were not in the top flange. They are for brackets that are part of the rear seat rudder pedals. The plan page from the rear rudder pedals show a nut plate that has 2 rivets on the same side. The holes in the bottom flange are for a K1000-8 nutplate which has the standard left and right wings. I drilled the top flange using the bottom as a guide. I then enlarged the middle hole to a #19 that will allow a #8 screw to go through.

IMG_4185.JPGBefore putting the halves together put torque seal on the bolts in the forward section.

IMG_4186.JPGAs you put the halves back together you can insert the forward control mount, seat belt lug and the 2 spacers. It takes a little time to get all the parts to line up so you can insert the bolt.


IMG_4188.JPGI decided that instead of just 2 spacers per end I would use 4 per end. I will make 4 more tomorrow.


IMG_4181.JPGThat’s where I decided to call it a night. That was a good 8 hours of work in the Hangar!

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