First of all, thanks to all for your answers and suggestions.
mikewmac wrote:Mike P. soloed on his AI "Pinocchio" models and created both the models and the AI FDE's himself. I haven't looked at it at all

...sorry Mike, reading the comments in the CFG, once I read Michael, I didn't waste time in reading also the surname...
I found the cause for a couple of problems.
The "Runtime error" is caused from fx_g91_ab effect. Removing it from cfg, the problem doesn't appear anymore. Very strange, it uses only the default texture fx_2.bmp, used in other effects without problems.
I'll install some Mirages to verify if I have the same problem.
I've changed a value in the contact point for the nose wheel of the Y, the wheel is ok on the ground, on the other hand, the yellow support for the tail is no more on the ground....
Mike P., if ok for you, I'd try some other changes and let you know, also for the T1
I know that test at 4x speed can cause problems, but I do not yet understand why some models at an airport stay on ground, at another float. Doesn't matter for now
Thanks, Giorgio