Things have been very well with my 110 except for some kind of vibration. It shows up mostly at the rear crutch / tail boom area at certian rpms (not full throttle). I experienced a crash sometime ago and the crutch was damaged. I repaired the break with a carbon fiber cloth/ superglue patch. I don't want to replace the crutch because I'm holding out for the aluminum one from L.M. if it ever comes out. The main rotor shaft appears straight and I have replaced the tail boom. The tail rotor drive wire is straight. The only thing I've noticed is "slop" on the main shaft/main rotor mounting. You can hold the main rotor with one hand and turn the main rotor gear for some distance with the other. It appears that the bolt or main shaft slot are worn. Would this cause a vibration? How much slop is normal? The heli flies great even with the vibration, I'm just afraid it may damage something else.

That slop is normal with brand new parts. I would say it probably slops around 15 degrees or so.

If you are worried, take the Jesus bolt out of the main rotor hub and take a look at it. After a lot of use they will get two small notches cut into them from where the sharp edges of the main shaft notch slop back and forth into the bold. If your bolt looks cut up, hey swap it out and keep some piece of mind. If the bolt looks good, slap it back in and keep on flying. Either way, the slop is normal.

For what it is worth,
Spiro

Thanks Spiro, the slop was the easiest thing thing to pick on. I've read in other chat where the vibration problem was the crutch. My crutch broke right at the top main rotor bearing mount. The repair is strong but might somehow have the main shaft out of line. I think I will go thru the balancing and tracking again. If it doesn't show up there I'll just live with it until a better crutch is available.

After checking the tracking and balancing both of which were ok, I found the main rotor / clutch gear mesh to be too tight. It was ok in spots but the m.r. gear was out of round. You could hear the wah wah sound when you turned the main rotor by hand. After loosening up the mesh the vibration seems much better. It actually took several attempts to get it right.