vibration problems

[darryl]

Had a crash a few weeks ago with my titan 50, I've rebuilt the heli replacing the following parts (below) but I have a vibration that seems to shake the whole heli

It seems to start at the tail and then get worse until the whole frame,undercarriage is shuddering. This is amplified and more noticable at the higher head speeds in idle up 1 or 2. When held in a side hover the tail servo is clearly pulsing back and forth at super high speeds, not travelling very far but continually moving none the less.

main blades
spindle
main shaft
main shaft bearings
wash out hub
D-links
Double links
Flybar
Paddles
tail boom
boom supports
tail gearbox case
tail blades
QUK tail pushrod
QUK tail grip assembly
tail belt
servo tray
undercarriage & skids

I took her out to dial it in and the vibrating started. Spent 4hrs doing the following little changes and trying it by getting it up into the hover.

I changed to a different main shaft - still no different.
Tracking is perfect so i really doubt its the feathering spindle.
Changed to a different set of mains thinking my new blades were out of balance but no change.
Tuned engine both ways incase it was causing the vibes but no.
Removed engine to check fan & clutch - both seem ok.
Checked everything was tight and well secured down.
Changed gyro & zeal tape - still there.

I am supposed to be going to our clubs Christmas fly in today but at the minute it looks like I'm going no where due to this

Any ideas greatly appreciated!

Thanks Darryl

[Mike W]

First question is .. which way the vibration moveing the heli ??? side to side or up and down ?? did u change the tail output shaft ??

[darryl]

i haven't changed that shaft as yet, tail blades seem to be tacking perfectly though. Heli is shaking side to side.

Thanks for the fast answer

[Mike W]

change the tail out put shaft then ... sounds like its bent m8e .....the tail spins at that high a speed u sometimes might not see a little bend in it ... and you say it gets worse when you go idle up ... change it and see ... .. Let us know how you get on ....

[darryl]

Will do, I'm at the G/f's house at the minute so once I go home I'll change it and let you know...

Cheers!