Torque Tube and Fins (3 hr)

Allen joined me in the hangar today and our primary goal was to get the torque tube properly installed so that we could get the stop ring on the end of it (if you recall, it won’t go far enough forward for the hole to be clear). We started unriveting parts of the bearing where the tube tab hits in the hope that if we could get the tube forward enough we’d make new holes. But that didn’t work, the thing is solidly riveted to the channel underneath on the bottom skin, so we took those rivets out too.

Eventually Allen got a large crowbar and was able to push it from underneath such that the stop ring hole was usable. I quickly put in the bolt in case it disappeared.

Some inspection revealed that the bearing could go back into the original holes, it had not moved. We attached the control stick and found that it was near impossible to turn the tube left and right, it was really tight against something. Our first thought was that the tab was rubbing on the bearing but it turned out that the problem was at the front end. In the picture you can see that the tube passes through a plastic fairlead before exiting through a metal hole. It was the metal hole that was tight on the tube making it hard to turn (and I now wager was making it hard to get the tube far enough forward).

So we used a file to enlarge the hole but not before Allen noticed that the hole in the plastic fairing was larger than the hole in the metal bearing which he thought was backwards – usually it is the fairlead that grips the item and it doesn’t touch the sides of the metal hole. The photo guide says that the tube doesn’t touch the fairlead so it may be that I have done it right, but I have filed a support request with Zenith for the answer. As it stands right now, the tension in the control stick for making turns feels about right.

We had hoped to revisit the rudder cables but the replacement parts (for the cable fairleads) I ordered had not arrived in time.

Allen left and I was about to do the same when I decided I’d finish the fins before the weekend was over. As you may remember (it was in the last blog post so I am sure you do) the rudder nose needs a lot of trimming. So I marked a line and set to work with the snips.

Re-installing everything on the plane, the elevator now moves freely to the stops.

I reattached the rear fin and backdrilled into the angles, and also put a couple of rivet holes where it overlaps with the forward fin. The rear fin interferes with the rudder and the stabiliser so it had to be trimmed too.

The two arms pointing back on the fin take l-angles inside to act as stiffeners

And that’s where the photo guide ends on this topic but I can’t help feeling like it isn’t done. Even with the stiffeners on surely those arms are going to flap about in the wind? It doesn’t seem right to me that they just sit out there. Also, right now they only just clear the rudder – if they are waving around in flight then I am sure they will interfere with the rudder so I might need to trim the rudder a little bit more. But I’m going to ask around about those fins.