Brent, thank you for posting the PF plans showing the direction for installing the 4" SIG bellcrank. I haven't done any precision measuring of one to get an exact dimension, but it eyeballs at under 1/4" offset between the pivot hole and the L.O. holes. I believe Mike said his intent was to get closer to equal tension on the two arms while deflected, not to induce any centering or un-centering. Basically, shortening the arm being pulled on most, while lengthening the arm that is being pulled on the least. I think it makes sense, but I'm not 100% sure I would notice the difference, either. Steve

Take a square, put it with one side along the leadouts, and the end aligned with the hole where the leadout goes through the bellcrank. If the other leg of the triangle falls in front of the bellcrank pivot, it's self-centering. Even on the little P-Force, this line falls about 3/8" inboard of the pivot, so it self-centers,. Larger airplanes have the leadouts converging at a shallower angle, and self-center more.

The effect in this case is that the line with the most tension has more tension for a given torque than the "loose" line. The lever arm for the "tight" line becomes shorter as you deflect it, and the lever arm for the "loose" line gets longer. That's *why* it self-centers. It's the same effect that causes heavier control effort with an offset handle (just much less of it).

Note that this is not an indictment, we all flew with bellcranks at least this much *unstable* without even realizing it for years.

Brett