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View Full Version : Vibration problem after rebuild


JezUK1
04-14-2009, 03:22 PM
This evening I have replaced the Head Block/Rotor houseing. I have also put on the new blades and a new feathering shaft. But I find when I throttle up the helicopter vibrates quite badly just before takeoff and still slightly vibrates while in the air. Also when I come to land and power down it does exactly the same thing. Can anyone put any light on this please?

Fendbass22
04-14-2009, 03:34 PM
Is the main shaft bent? That is hard to see by eye after a crash.

The E-flite blades (not sure if that is what you are using) more often than not are out of balance brand new - at least that is my experience.

JezUK1
04-14-2009, 03:37 PM
No sorry I forgot to say its a brand new shaft. I have never had any problums with the stock blaes before. hhhmmm

fast400
04-14-2009, 03:42 PM
This evening I have replaced the Head Block/Rotor houseing. I have also put on the new blades and a new feathering shaft. But I find when I throttle up the helicopter vibrates quite badly just before takeoff and still slightly vibrates while in the air. Also when I come to land and power down it does exactly the same thing. Can anyone put any light on this please?

first off did you put the brass step washers back in between the flybar frame and the seasaw flybar holder?
you may loosen the jesus bolt and wiggle the head to make sure its seated properly

did you messure the distance between the flybar frame and the flybar paddles for equal distance.

did you put back the 4 shim`s and 1 step washer perside on the feathering shaft between the headblock and the blade grips

how tight do you have the blades

conetica
04-14-2009, 03:55 PM
I also had a set of brand new eflite blades and they were way out of balance. Also check the first main bearing on the main shaft, its usually the first one to be damaged in a decent crash.

JezUK1
04-14-2009, 04:07 PM
Were or what is the jesus bolt which you talk about wiggleing?
Yes the flybar frame and the flybar paddles are equal distance.
I did put back all the shims etc into the feathering shaft.
The blades are not too tight or too loses.

first off did you put the brass step washers back in between the flybar frame and the seasaw flybar holder?
Do you have a pic of this so I can see were they should be?

fast400
04-14-2009, 04:38 PM
Were or what is the jesus bolt which you talk about wiggleing?
Yes the flybar frame and the flybar paddles are equal distance.
I did put back all the shims etc into the feathering shaft.
The blades are not too tight or too loses.


Do you have a pic of this so I can see were they should be?

the jesus bolt is the screw with the lock nut that hold`s the head on the main shaft.

and make sure you have these line pins in the washout block
first pic is the brass washer i spoke of, the step goes towards the bearing just like ones on the feathering shaft
second pic is the bolt i spoke of
third pic is of the alignment pins or whatever their called

Slyster
04-14-2009, 05:02 PM
You balanced the blades and centered the flybar to within a millimeter?

JezUK1
04-14-2009, 05:03 PM
Wow your a star.

Yes I have the brass washer all in place both sides.
Yes the alignment pins are in place.

As for the bolt, what Im I feeling for? Should the head move a bit?

fast400
04-14-2009, 05:08 PM
Wow your a star.

Yes I have the brass washer all in place both sides.
Yes the alignment pins are in place.

As for the bolt, what Im I feeling for? Should the head move a bit?

yes loosen the bolt and wiggle the head to make sure you have it seated on the shaft properly.

and if youve replaced the feathering shaft the mainshaft. and everything else is in line, then like blade tightness and balanceing are good. then you have a serious problem somewhere.

JezUK1
04-14-2009, 05:24 PM
Looks like a trip to my LHS :thinking