Horizontal trim tab drive arm not long enough

[alaskabearhawk]

Interestingly enough, I was working on the trim system and I found a new issue. I went with the airfoil-shaped ribs for my horizontal stab. When I was checking the fit of the Aurora MM-3 bearings on the trim drive side something seemed amiss. I couldn't quite put my finger on it until I looked from an end view. Since the rib profile gets taller as you move forward, I found that the trim rod end won’t clear the fabric when bolted to the arm! I went back and saw that Pat Fagan and Russ Erb both made the arm a bit longer. The solution I came up with is to cut the old arm off and make a new one a bit longer. By welding it on the torque tube closer to the fuselage, I can offset the trim drive arm and still maintain a straight push on the trim drive rod. The front bolt goes in toward the fuselage, the trim tab side goes in the opposite direction. Any thoughts on this fix? Is there something I can do different?

[Gavin Chester]

You could cut the end off and install a removable one with a longer arm as needed.
I made my end removable to allow the torque tube to be removed should I need to. ( made it easier for sandblasting and painting )
I also put a small hole at each bearing area in the torque tube and a small piece of oil filled felt wick material at each location to keep it lubricated.

[alaskabearhawk]

Now that is a great idea. Thanks Gavin!

[alaskabearhawk]

I talked with Bob yesterday and explained the situation. He said I could do what I had planned or just to leave it alone. He gave me two options. One is to make a small blister out of plastic or aluminum around the fabric to make clearance for the bearing end. The other is to make a fork out of .050 on that end of the rod and that would give me the clearance I need. He said by lengthening the arm by, say 10%, I would have to compensate the arm on the trim tab end the other way to keep the same amount of trim travel. I like that because I don't have to go backwards and redo what's already done.