516 Tail Hub+Blade Holder Tolerance Problem

[sawacs]

Okay, I have finally ran into an issue.

I know the hub and blade grips are supposed to have play which is built in on purpose.  However, the problem I have ran across is the amount of inward and outward play between the two sides.

The difference in inward and outward play between the different sides of the blade grip/hub is enough that I would not even attempt to fly the heli because vibrations would be a guarantee.

Yes, I have checked to make sure the correct washers, bearings etc were installed correctly and they are.

What do I need to do to resolve this issue?

Thanks!

[Vince Young]

What do you mean by “The difference in inward and outward play between the different sides of the blade grip/hub”?

[sawacs]

What do you mean by “The difference in inward and outward play between the different sides of the blade grip/hub”?

What happens when you grab both ends of the blade grips and push inward towards the blade grip hub?  The blade grips move closer to the hub or center of rotation right?

Now, when you grab both blade grips and pull outward, away from the hub, the blade grips get farther away from the hub or center of rotation  right?

The center of the hub marks the center for the rotational mass that swings around at a rather high rpm.  With all things being equal, if you extend one of the two blade grips farther from the center of rotation that the other blade grip, you create an out of balance condition because you are moving the mass of one of the blade grips farther away from the center of rotation compared to the other blade grip.

Hope that makes sense..

[Jon Yarger]

Are you sure one grip extends further? Don’t pay any attention to the distance that one travels compared to the other. That is unimportant and can vary. The only thing that matters is the distance from the center of the tail shaft to the center of the blade bolt when the grips are Fully extended. Are you sure those distances are different?

[sawacs]

Are you sure one grip extends further? Don’t pay any attention to the distance that one travels compared to the other. That is unimportant and can vary. The only thing that matters is the distance from the center of the tail shaft to the center of the blade bolt when the grips are Fully extended. Are you sure those distances are different?

John, thank you for the reply. 

I will definitely take some measurements from the center to the bolt hole on the blade grips and go from there.

The tail blade holder assembly looks exactly like the holder on my N7.  In a worst case scenario, I could always swap out the center hub and or blade grips from the N7 and measure again.

Cheers!

[Jon Yarger]

No problem. The tail assembly is the same as the n7. You can also run it on the bench with no blades to check vibes. I have a feeling it will be ok under load.