450 Too much play on the main shaft?

[pstelzer]

Hi all,

Just repaired an Align 450L after a crash. Replaced the main shaft, among many other things. But now there is a lot of up and down movement on the shaft. It's held in place at the bottom by the autorotation bearing against the bottom main shaft bearing, but there seems to be nothing holding the top of the shaft in place. You can see a black band at the halfway point in this video, and I guess there are supposed to be shims underneath that to rest against the top bearing, but the band is the same diameter as the shaft itself, and it won't hold a shim or washer underneath.

Thoughts? Is it safe to fly?

https://www.youtube.com/watch?v=WVUm8wN251A

 

[Smoggie]

Looks to be a non-genuine shaft. The genuine Align shafts have a 'lip' machined into the shaft. Copy shafts dont have the lip, instead they use a retaining collar that locks to the shaft with grub screws... So either you need to get a genuine Align shaft or you need to find a locking collar.

And no, you shouldn't fly it like that.

 

[trainrider06]

As Steve said you have either a different shaft from something like a Garett, or tarot or HK that requires a shaft collar, or you'll need to get a genuine Align shaft....
As you can see the Align shaft has the lip as he is talking about resting against the bearing.....

 

[pstelzer]

Thanks for the replies! I took a look at my parts collection, and I found a collar! There is now no play on the shaft.

As an aside, when I took the shaft out, I could see it was pretty heavily scored. Additionally, there had been pretty nasty screeching coming from the helicopter when I powered it down. Could these be related? Sure enough, it turned out the screw on the bottom of the aileron servo wasn't tightened all the way, and it was rubbing against the shaft. I tightened the screw and no more screeching. There sure are tight tolerances on this helicopter!

 

[D.O.G.]

Good catch on that screw not being tighten all the way pstelzer. That could of been ugly. You should check all the screws to make sure they have thread lok on them. If one came loose maybe other can be on it's way.

 

[Smoggie]

I think I've spotted another disaster waiting to happen.. One of the balls isn't fully screwed into the swash:



You maybe need to give the whole heli a really good going over, it just takes one mistake like that for your flying session to end badly..

 

[trainrider06]

Oh boy! Yep that's definitely gonna hurt if not fixed! Remember thread lock too!

 

[Admiral]

I have always installed the collar up the other way so that the raised section rides on the inner race of the bearing only, not sure how much difference it would make, just thought I'd add my two cents worth.

 

[Smoggie]

I have always installed the collar up the other way so that the raised section rides on the inner race of the bearing only, not sure how much difference it would make, just thought I'd add my two cents worth.

Yeah, that's how they are meant to go with the raised part toward the bearing. I think maybe the collar in this case has raised parts on both ends?.. if not it should be turned.

 

[pstelzer]

Thanks for all the great advice. I didn't even see that loose bolt. Now thread-locked and tightened. Will go over the heli very closely before flying. BTW, Smoggie - the collar has raised parts on both sides, as you suspected.