Weeks 96-103: Inside fuselage

Shortly after my last update I mentioned the pushrods and heater assembly I was missing to Scott with Sling in Torrance. He had all of the pushrods and was able to get the heater quickly as well. This saved a bunch of time waiting, so a big thank you to Scott!

During the short wait for those parts I installed the elevator autopilot pushrod and made the necessary changes to the tail and wing harnesses for the GMU-11.

I then worked on the rear seat heating channels. One complaint I have heard about with the Sling TSi is that the heat does not make it to the rear seats very well. I am guessing part of this is that the air has to pass through a channel along the outer skin. I decided to put in a thin layer of insulation in the channel to see if that helps get heat to the back. I also noticed there is a flange on the front inside skins that creates a restriction in the channel. I decided to unbend this most of the way to minimize the restriction. If that is an issue I can easily come back and re-bend it later.

I also test fit the rest of the ventilation components and realized that my parts don't match the latest instructions. I do think I understand the intent, so I plan to just make it work. I did discover that I will need some way to actuate the fresh air intakes. That was not put on the panel I got, so I plan to just add cable pull control with a "cabin vent" insert. I will have to drill a couple holes in the panel, but I think it will look fine when it is done.

After the heat channel inserts were installed I put in the front skins. I mocked up the rear skins and the upholstered side panels to see what it will look like when finished, it is going to look great! Before the rear skins could be installed I needed to get the front seatbelts put in. This was straightforward, but I did add the Teflon tape around the cutouts that the front seatbelt reels pass through to help protect them.

At this point I got the rest of the pushrods so I got to work on installing the nosewheel steering and aileron ones. Those are done along with the leather boots that seal the steering pushrods through the firewall. At some point in this process I also test fit the center console and realized that the front seatbelt latch points need to be removed until those parts are in since the bolt point is on the inside and the strap has to pass through a cutout. I am installing LEMO jacks along with the traditional GA headset jacks, so I had an extra hole to drill for both the rear seats and for the front seats inside the center console. I also drill a larger hole for the USB ports that will be installed in the back of the center console.

One issue I ran into was that I couldn't find one of the brackets that attaches the lower part of the rear seats to the outside skins. I am pretty sure I have it somewhere, but after looking for about an hour I decided I could use the other side to fabricate the missing one. I think this ultimately took less time than I spent looking for the original.

The other big issue I had was the elevator controls were too tight. I measured the force it took to pull on the stick and it was over 3 pounds. The autopilot servo only has enough torque for the equivalent of 6 pounds pulled on the top of the stick, so in addition to it just not feeling right I was not comfortable with half the available servo torque being used to just move the controls.

I initially tried lubricating the large elevator torque tube since I noticed it seemed tight when it was first installed. This helped some, but it was still not where I hoped it would be. After quite a bit of work on it, I decided to try using bearings on the outside of the torque tube instead of bushings. I ordered some online and started to try and figure out how to make them work.

In that process I drilled out the rivets holding the torque tube and unbolted it from the pushrods. As soon as I had it disconnected from the smaller (rear) torque tube I realized it was actually moving very smoothly. I was so focused on the large one I had not thought to try lubricating the back one (which seemed ok when initially installed). I finished removing the large toque tube, cleaned it and re-lubricated all the bushings with white lithium grease then lubricated the back one as well. That made a big difference, getting the force required to move the control stick down to 1.4 pounds. It also feels like I would expect it to now.

Happy with that I re-riveted the large torque tube back in place and put in the locking collars on the small one. Getting this squared away also let me install the flap actuator and start on the inner seat rails. The next steps will be installing those and the center console as well as the rear inside skins. I am also going to start putting in the avionics rack and avionics as well as the wiring harnesses that go with them.