Floor under Back Seat

For some strange reason, there is no floor under the back seat. I guess Sling expects the back seat to cover any cold air leaks and stop stuff from falling into the space below. This seems really sub-optimal, dangerous, and needs to be addressed.

Without a floor, the seat belt buckles can be pushed through the seat and fall into the space below which houses many important linkages that are needed to fly the plane, so that could be bad. Also there is a huge amount of cold air leaking into the cabin from underneath the seat.

To fix this I decided to add aluminum floor panels under the rear seats, to close up the space. They are mounted with rivnuts, covered in carpet, and easily removed for inspection. The final result shown in the first picture. 

It is an easy build; you need a rivnut tool, metal scissors, rubber mallet, and a few others. Measuring, fitting, and installing requires various advanced yoga poses, but it is doable.

First I made a cardboard template for the two panels, measured it and ordered the aluminum sheets. When they arrived I cut them to size, and formed the bottom panel around the bottom of the seat with a rubber mallet. It bends quite easily and fitted first time (almost).

Here are the parts I used:

• 0.032" Aluminum Sheet 6061-T6
• 38.5"x7.5" - back panel
• 42.0"x16.25" - floor panel
• Some u-channel rubber edge trim
• M4 rivnuts and bolts
• Spray-on glue and some carpet scraps (thanks TAF)

I cut the panels to size with metal scissors, and bent the edges with a rubber mallet to fit them in place. The seats belts need to be slotted through the aluminum, so I created some slits in the right places, and to avoid abrasion lined these slots with rubber u-channel (see below).

The end result is great. I can take out the back seat easily (I usually don't screw it down) and create some extra cargo space for long camping trips. It stopped most of the major cold air leaks, and it stops the seatbelts from falling into the bottom of the plane.

One interesting side effect was that it affected the airspeed. By plugging any holes you affect the cabin pressure, which affect the pressure measured by the internal static port. So I would highly recommend installing an external static port if you decided to add a floor.