Things done today:
- Installed rivnut and secured trim tab hinge pin
- Loosely installed bolts in elevator to HS hinge
- Went through Empennage mounting hardware and figured out where it all goes
I finally heard back from SA TAF about the trim tab hinge pin. They said go ahead with the planned install of the rivnut. So finally I could finish up the elevator. I installed the clevis to the trim servo and got it close to center. This will be adjusted later so I just put some heat shrink on the cotter pin so it doesn’t fall out and to remind me this needs to be finished. I also attached the elevator to the HS mainly to make sure everything looked good and lined up. I’ll probably leave it like this and find a place to store it as a whole assembly.
Installed the M3 rivnut and secured the hinge pin using the part I made from the end of a hinge section and an M3 screw with some medium thread lock. It holds the pin really well and the trim tab moves nice and free. I did try to install the clip on the inside of the bend, but I noticed that the pin did have a tendency to try to slip out a bit. This is because the clip and the pin were both in the same rotational plan. With the clip on the other side of the bend the pin doesn’t try to slip out of it because the rotate against each other.
Clevis is installed on the trim tab side. This will need to be fine tuned later so I didn’t bend the cotter pin. I just put a long, obvious piece of heatshrimk on it so it doesn’t fall out and get lost.
Loosely put in the AN4-5 bolts and washers on the elevator/HS hinges. The washers were a pain to get in especially the second one on the inside. I ended up using some masking tape to slip the washer in and hold it then pulled it out once the bolt captured the washer. After some practice it wasn’t too difficult to get a hinge done. I also made sure to point bolts inwards.
I installed a short 3.2mm rivet and a wire tie clip to hold the wire and connector. The rivet is covered by the access panel so you don’t see it.
A photo of the installed trim tab.
A shot of the finished HS and elevator.
I wanted to secure the hinge pin for the trim tab, but the way my hinge was cut from the factory it wouldn’t allow me to do it the typical way other builds are securing it which is by drilling a small hole on either end of the hinge and then after inserting the pin putting safety wire through the holes. This keeps the pin in place and if you ever want to remove it you just cut the safety wire and push the pin out using another pin or something smaller diameter. I need to thank Peter V. and Pascal for all the support on this and the great ideas. What I decided to do was the RV style technique by using a longer pin and bending it in a way were you can install some kind of screw of clip to hold the end. I emailed TAF with this idea, but haven’t received a reply yet so I’m waiting to drill the hole for the rivnut. I’ll email them again just to be sure it’s OK to proceed.
Today I bent the hinge pin and made a clip out of the end of another hinge. The last bit is to drill a 4.9mm hole for an M3 rivnut in the side of the elevator rib so that I can attach the clip to the side of the elevator with an M3 screw and some thread lock of course. I actually really like this idea because it makes the pin removal really easy, just unscrew the clip and pull out the pin. It is a tad bit ugly and I did try to put all this on the inside of the trim hinge but there just wasn’t enough room there and the bend in the hinge ping was a very tight 360º bend back on itself. Here’s some photos of the almost finished hinge pin.
Side view. The clip will attach with an M3 screw into a rivnut
Time: 3 hrs
Filled the rest of the Elevator rivets and sanding all of them. I need to order the trim servo so I can put that in and the connector ends should be here in a day or two so I can finish up the wiring. I wanted to drill the hole in the trim tab piano hinge for the safety wire, but it seems like my hinge is a bit different the other builders. I don’t really have much room to drill the hole. I might be able to drill the end of the wire that sticks out past the end of the hinge and then another hole somewhere close, then I can string a short wire between that and the hole in the hinge wire.. Not the proper way to do it, but it would at least prevent the hinge wire from falling completely out. If anyone has any ideas about how to secure the hinge wire please let me know. Some photos are below that show what I’m talking about
Elevator with rivets all sanded, now just need to finish up the electrical work.
Here’s the right side of the piano hinge. That small triangle bit of aluminum is where I’d have to put the hole for the safety wire. Although it doesn’t need to be a very large hole… a little more the 1/32″ I believe, I still don’t think there’s enough material there.
And this is the left side. There’s a little more material on this side, but it’s in the side that moves so I can’t put it there either. Maybe I can do two holes on one of those larger areas and loop it through… Hmm that might work.
Time: 2.5 hrs
Worked on the trim tab. Not a lot a parts… the time consuming part was cutting down the rivets. I came up with some quick hacks to cut a few down at once.
drilling some holes in a block of wood so I could hammer out the mandels of the rivets
I found some tribe mould that was 6mm thick, drilled a few holes in it and fit the rivets in to use as a cutting guide
Here’s the finished rivet next to the original 8mm (length) rivet