check control stick bracket attachment to the torque tube

[kshunz]

In the second condition inspection of my FX-3 (with about 185 hours), the experts at Hood Aero noticed that I had play between the aluminum control stick attachment brackets and the steel torque tube that connects them. For both forward and aft sticks, we could see the brackets move relative to the CherryMAX blind rivets that attach them to the torque tube. Not what you want to see.

The rivets were removed, and we checked the size of the holes. For the 5/32 rivets, the holes should have been drilled with a #20 bit. The holes in the steel fit the #20 bit perfectly. But in the aluminum bracket, the holes fit a (larger) #18 bit. They looked perfectly circular, with no evidence of elongation. It seemed like the holes in the aluminum bracket were drilled with the wrong bit, yet Pete tells me that they're drilled in one operation.

Each hole was reamed to accept an oversize CherryMAX rivet, and I'm back in the air.

I recommend that you check your brackets to ensure that there isn't any play.

[Andy]

Thanks for the warning.

I check stick play when I do my inspections on my FX-3. I have not seen play between the stick bracket and the torque tube but I'll look closely next time I'm at the hangar.

I did find excessive roll play in the front stick pitch pivot bolt. I was able to reduce that by slightly increasing the pivot bolt tension which required a washer change. Now the stick pivots on the bolt and the bolt does not rotate or rock.

The pitch pivot bolt holes in the stick attach bracket appear to be larger than necessary.