You may be thinking about eczema, but I'm thinking about that funny thing that happens when you skin up a model and then export it into Flightsim only to discover something has gone horribly awry and your model suddenly looks like something out of a Japanese horror film. Usually this is caused by having animated bones with scale applied to them. Or by forgetting to make sure all of your vertices have skin weights applied to them. Or by some other unknown gremlin in the system. However, if you are having that problem on your models, and you have more than 128 skinned bones in that model, you may have just discovered a bug in our engine that we are working on fixing.
Apparently, only the first 128 scene graph nodes can be exported as skinned. What does this mean exactly? Anything with animation on it gets exported as part of the scene graph. You can export as many animated parts as you want. However, in the current incarnation of Flightsim, only the first 128 nodes can be part of a skin. "Why didn't you find this bug before you shipped?", you ask. Well, in the interest of trying to maintain some performance, we kept our bone counts down below 128 per model. So we as artists never actually ran into this issue. Leave it to the third parties to push our system to its breaking point. ; )
The fix for this should be part of the SP1 that we are working on right now. I believe we are trying to bump the limit up to 1000 skinned bones and are also working on implementing skinning on 1.0 and 1.1 cards as well. Which means more people will see more bones and will see them on more cards.