Rudder cable adjuster

[Battson]

The spec for aviation turnbuckles is a maximum of 7 threads difference. I believe it is allowed 3 threads outside to 4 threads inside, per side of the turnbuckle. I measured 7 threads on the specified turnbuckles and it is only 1/4". So each turnbuckle, in the size specified, can only allow a range of adjustment of 1/2", or +/- 1/4".

So at least one inch total adjustment for the system, then.

Start with 1/4" per 7 threads, 2x for the thread at each end of the turnbuckle = 1/2". Then you have one on each cable, so 2x again, total adjustment is 1" to keep the pedals lined up with each other.

P.S. the licensed aircraft engineers tell me the "three threads showing" rule is only a starting point for installing new cables. You can adjust a lot more widely than that when adjusting a pre-existing system. Several of my cables are outside that rule now, and signed off as satisfactory. So I suppose at least 2 inches total for the system, which is tonnes given the short pedal throw on the Bearhawk.

[svyolo]

I will look again when I get back but the turnbuckle bodies that I have aren't very deeply threaded.

In my case, I already bought the turnbuckles so it is already "sunk" money. But I sure would like to not add any extra weight that doesn't appear to have a lot of value. 1 threaded stud and fork have about the same adjustment as 2 turnbuckles, at least in the size we use.

[svyolo]

I got my aileron cables back from ACS, and very quick to boot. I had them swaged, although just swaging one side and cutting them long is probably just as easy, and put a nico-press on the other end. At some point, no matter what, you have to measure and cut. While I had the wing struts on, I measured.

The aft aileron cables are almost a straight shot, very easy to measure accurately. The forward ones, not so much. I think the only way to accurately measure the forward ones is with an actual cable, so that is what I used. Going through 3 pulleys would cause too much error if you used a string of some kind.

ACS lines are well within 1/8" of what I ordered, and one end of each one has a threaded adjuster with an inch of adjustment.

I think the ailerons could be done best with a single turnbuckle overhead in the cabin for adjusting tension. Adjusting the length of the two forward cables with the threaded #MS21259-4RH. The final tensioning done with the turnbuckle. I am going to try to do it first without any turnbuckle, but 1 will make it easier to tension.

I would do the same for the elevator. One threaded adjuster on one cable (or maybe one on each), and 1 turnbuckle for the final tensioning. Once again, I am going to try to do it first without any turnbuckle. If it doesn't work out, I will cut the cable and add a turnbuckle.

One #MS21259-4RH gives you the same adjustment range as two turnbuckles, for much less weight, complexity, and cost. At most, I will have 2 turnbuckles on the whole plane.