Wed Nov 10 2010

Sub floor details

Yesterday was beautiful. A perfect day for airplane building. Unfortunately, Kerin's car decided to stop running, so I spent the day fixing that. Turned out to be a bad camshaft position sensor. Sigh. Today was also a beautiful day so I got back to work on some of the remaining details of the sub floors. I decided to work on the attachment of the aft flange of the sub floors to the spar cover panels. It seemed odd that the left side was a great fit with the spar cover panel...

...but the right side had a gap.

It turned out that the flange on the right side was bent a little too much as you can see here with the two panels side by side. I tweaked it with the seaming pliers.

Next problem was to figure out a way to deal with the fact that the bottom screws of the central spar cover brackets were set slightly too low to line up with the aft flange of the sub floor panel. Somehow I need to figure out a way to move these holes up about 5/32.

After some head scratching, I decided to remove the bottom nutplate and replace it with a miniature single lug nutplate. The top rivet location from the previous nutplate would be reused as the bottom rivet for the miniature nutplate. Since the miniature single lug nutplate has a smaller spacing between this rivet and the screw location than the original nutplate, it'll move the screw location up as desired.

In order to facilitate drilling, I made up a little drilling jig. I'll probably put this to use tomorrow when I make the modifications to the bracket.

Well, after quite some time, I had the aft flanges of both sub floor panels drilled to the spar cover plates. The lower inboard screw holes of both cover plates had been slotted by 5/32 to allow for the new screw location. I also drilled and dimpled the nutplate mounting locations on the cover plates.

The fuel selector cover needed the lower hole slotted as well (near the bottom of the photo).

With that work done, the only thing left is to remove the original nutplates at the lower screw of the inboard spar cover brackets and replace with the miniature version. I'll do that tomorrow. For the rest of the evening, I decided to work on the brackets which will be used to mount the firewall sub panels to the firewall.

After measuring, marking, trimming, and deburring, here they are. From top to bottom, these will be used on:

  • The diagonal stiffeners
  • The outboard vertical stiffeners
  • The inboard vertical stiffeners
  • The left and right portions of the top stiffener

I think I'm going to need to cut the left inboard vertical stiffener into three pieces since it needs to overlap the bracket which supports the rudder pedals at mid span. I'm planning to pop rivet these on, so their installation should be quick.