On Tuesday, 3 March 2015 20:47:42 UTC, Movses wrote:
The spherical bearings that mate to the spar spigots in my Astir CS are binding when turned to larger angles.
When rigging the wings, a slight misalignment of the spigot jams the bearing and any further progress becomes impossible until you pull the wing out and unjam the bearing using a wooden dowel (it wouldn't turn by hand once jammed).
This makes putting wings together a royal PITA.

Closer look revealed that the far side of the "outer race", is worn out and pitted and likely is the culprit.

The bearing in question is SKF GE 20 ES, which seems to be easily available.

It appears to be pressed in into a metal sleeve that is bonded into the wing root, and four areas are punched in to further lock it in place.

We couldn't find anybody local who would readily know the process of replacement of that bearing.

Is anybody familiar with maintenace/replacement of these?

- Is that bearing replaceable? It seems like the only way to extract it is to slide-hammer it out and tap a new one in.
- How critical is it? I assume that it radially transfers the entire load of the wing

-Movses

I had precisely the problem you describe, in all its aspects, with my G109B.. It was caused during rigging by striking the bearing when trying to insert the main spar spigot. The engineer removed the whole unit from the center of the fuselage using a balk of timber and a heavy hammer, and replaced it with a new one (the bearings on both sides had this problem).

I have been much more careful since then, and offer up the spigot very slowly.