Tail Wag after a crash

[tracker2]

Well I crashed. Yes I'm new to the hobby, And I try not to fly beyond my very little skill level, but I Crashed it after 25 successfull flights on the Trex-450. I had to replace the tail boom, tail braces, and link rod, tail housing, bearings, and shaft.Now that I have got it all back together took it out for a test flight, sure enought I developed a tail wag and it bounces back and forth about 1 - 2 inches duing normal tail in hover. I haven't changed and tail blades, grips or hub, any idea's what I need to be looking for and steps I need to take to trouble shoot a tail wag after crash issue.

Thanks Tracker

[mrmarc]

Sounds like you got some vibes. Do you see your vertical stabilizer shaking as you spool up? Does it still shake when you go into IU even on the ground?

Double check the head. I noticed that the gap at the bottom of my rotor housing where the jesus bolt secures it to the shaft had split a bit wider, thus allowing my rotor head to rock back and forth (perpendicular to the jesus bolt axis) ever so slightly. There could be other damage to your head, but basically, you will want to check there.

Are your tail blade grips still good? I bent the arm on one of mine in the last crash, and while I did manage to bend it back, it took a few tries before I could see my tail rotor tracking properly (with the heli secured and looking at it from behind at 0 pitch to the tail rotor, obviously without the main blades on).

I've read that some people a brace on their tail supports to remove/reduce vibrations. You could try putting a zip tie or two across both tail braces, making it tight enough to hold em snug (imagine pinching them together with your fingers). Basically, simulating one of these.

Since you had to replace the tail shaft, is your belt tension correct? I assume it's a belt because your sig says you have a 450 Sport...or are you using a TT?

[tracker2]

I don't know if it's vib's it doesn't move or shake on the ground, or while in IUmode on the ground, only once I lift off the ground will it wags from left to right about 1 -2 inches, and it's becomes unstable, I did notice the belt is had become loose again, Which I just try to tighten, I've the frame hardware due to the need to replace the body screw the have round out and won't let me tighten the boom any more., Tail mount is Still a bit loose. I also order a new Tail servo, thinking it might have become damaged in the cashed. I can't see and more damage in the tail blade grips. I also pulled the tail blades and check the balance. they are still good I don't see where the tail hub was bent. but I could be wrong.

Any advice?

[Luigi_tuga]

And what about your tail grip bearings. Can you move them freely or they are notchy and binding on some points?
Most of the wag problems are because of worn-out bearing in tail grips, and those on the 450 are tiny...

[tracker2]

After double checking the tail grip and bearings,I found no slop, or extra play. no binding seems very nice-smooth. althought, it took a while but during my investigating / testing, I was able to watch, as the wag became larger to doing about 5-6 inch wag and then no responce from the tail servo within a 30 second time frame. Seems the tail servo died on me as a result of a hard driect tail impact crash. Just luckly it was under controlled condititions when it failed completely.

I'm waiting on the UPS guy to arrive to further investigate.
Thanks for your help guidance..

[PcChip]

I sincerely hope it fixes your problem. If not come back and let us know!

[tracker2]

Problem resolved. The Servo arrived and I found it NOT to be the problem. Never open the package, It will remain as a spare.. It was when I discovered Bob Whites Video's on the site looking for an answer to the tail wag, after taking the time to review each of his vids, finding them very helpful, informative. I couldn't feel any binding until I started taking things apart when I found the tail blade grip had a defective inner bearing, Once i Installed the new tail blade assy, new blanced blades, and after a minor tweck to trim. She fly perfect holding solid heading..

Luigi_tuga was right I can hear him now " I TOLD you. "

Thanks all for the support on the Site.