Rear floor shutoff skin and transponder antenna hole cover

TLDR

• Installed the rear floor shutoff skin
• Made a plate to cover the (old) transponder antenna hole

Details

Rear floor shutoff skin

Pretty straightforward except it’s a little tricky to get to all the rivets especially the 2 rows next to the outer skin. In theory if I installed this plate before the inner skin it would have been much easier. But it was still doable. I basically followed the standard steps of cleaning, test fitting, deburring, riveting.

Rear floor skin

I also clecoed the floor skin to add some strength to the structure. I did not rivet the floor yet because the brake lines runs under it. I want to bleed the brake first so I know there is no leak under the floor.

On the copilot side of the floor, I made a small mod by cutting a 2”x2” hole directly above the transponder antenna, and made a plate to turn the hole into an inspection access. I am not sure how to access the antenna’s BNC connector without this inspection access. It took about an hour extra, but I think this will be worth it in the long run.

Old transponder antenna hole cover

The factory pre-drilled hole for transponder antenna is way too difficult to access so when I installed my antenna I moved it aft to under the rear row. I no longer need the hole in the original location, so I made a cover plate to close the hole.

I measured and cut a 2.5” x 2.5” plate, and drilled 8 3,2mm holes around the edge, then transfered the holes onto the fuselage. Easy job.