Heli shaking badly...

[Boz]

Hi, I attempted to just search this subject cause I know its been talked about enough. But, for some reason results on search didn't turn up good.

I have a Trex 450 SE that sat unused for about 3 years--a while back I took it completely apart (except for a few things like bearings that were too hard to get out) & re-assembled it. The last thing I did a couple days ago was to set-up gyro/tail per Finless vid which went well without any issue's (401/S9250).

Even though I know I should have done some pre-flight check ups, I wanted to just fire-it-up on ground in hobby room & see what happened. I threw on some CF blades that are almost identical in weight, but no other balancing was done--- within a minute I discovered that I didn't put threadlock on the screw that connects hub to the tail blade grip--that came apart--but since metal ball link on grip remained connected to tail link, it rotated smacking the case & boom a little before I could get it to stop. I don't know if I took any teeth out of the belt yet, but it appears that no other damage occured--luckily.

What I am most concerned about is the terrible shaking the heli was doing on the ground before this happened. I never did yet replace the old O-rings (few years old from sitting) on the feathering shaft--is it possible that this is part of the problem? & I know I had the main blades on a little tight, but it shouldn't have shaken that much just from that. Being that I completely put this heli back together & that I'm not yet the most talented around--lol--could you guys let me know the possibilities of the shaking so I can get started on it? Thanks, Steve.

[pmflyer]

I have a good amount of vibration when the tracking is off. Or bent spindle/main shaft. Also check belt. It will shake a little bit until the head speed increases. If the heads speed is fast and it still shakes then it's mechanical setup or something is bent.

[ziper_it]

I would check blade tightness, when too tight I see the worst vibrations.


Francesco

[Starcruiser]

if the motor is too tight to the main gear it will cause vibes too.

Things to check;

Tail belt too tight
bent main shaft
bent feathering/spindle shaft
blades out of balance (mains and tail)

Dampers can cause that too, those are the O-rings you mentioned, if they dried out, replace them, they are cheap

[Boz]

Thanks for reply's & list. I know for a fact that the main gear is really tight w/motor pinion--I thought all that could happen with that was more energy used = less flight time--will back that off a hair.

Tail shaft shouldn't be bent cause it has never been in any serious FF, only hovering & only recall having a tail strike in garage.

None of the blades are balanced yet--so tail blades need balancing too?

Tail belt may be too tight--will check

After doing all of this, if problem still persists, I'll go ahead & replace Dampners, just ordered some yesterday. Thanks, Steve.

[Starcruiser]

Boz, if the blades are out of balance, yes it can cause bad vibes. Can also cause tracking issues if the center point (CG) is different between them as well.

Check the main gear jesus bolt, if this is too tight this will cause warping of the gear and vibes too, it should rotate without any oscillation (or pretty close to it). Good luck.