Poopr,

Now that's a funny screen name for sure. But I'm thinking it has something to do with your work.

Anyway, to help ya somewhat. The best way to track down that type of vibrations is to start removeing things.. Take off the main blades and rotor blades first off. Then spool it up and see if you have any vibrations, if you do, then the flybar is in needs for some fine tuning. Measure to make sure they are the same distance from the head. If it spools up with no vibration, then slap the tail rotors back on. If you have a vibration then, your tail blades need balancing. Doesn't take but a 1/2gram. If your at a point now that there is now vibration. Then you need to recheck your main blades. 1/2 gram can cause vibrations.

Hope this helps ya,
Dave