Vibration in tail of Blade 400

[kmahler]

I bought a used Blade 400. After replacing the main shaft because it was bent, I find that the tail vibrates. I checked the tail blades and they are exactly the same weight down to 100th of a gram.

This is my first larger than a Novus or mSR heli.

Kevin

[Nitroman2478]

Check the tail shaft.

[n6nev]

remove the main blades first, then the tail blades and retest, mine turned out to be the tail blades, and mine also balance to 100th of a gram! I tried 3 tail rotor assys stock, eflight alum and now sonix, same result

[Cailid]

If the main shaft was bent then the feathering shaft is probably bent too. The tail shaft could be bent. Also check the tail boom.

[Blade400Rich]

I tried everything from all blades, all shafts, new belt, fins, gain, ball positions, etc etc..
I spent three hours on Friday changing all the tail associated bearings and that finally (8 months) sorted it. My guess is, it was the upper tail drive gear pulley bearing, which you have to split the frame to remove, nice job.

[n6nev]

I have install all new crermic bearing in the frame and the vibration still go's away when I remove the tail blades. tryed different blades, belt, I am using a sonix tail assy with align blades,

[Blade400Rich]

align blades? are they longer than the stock e-flite blades?

[n6nev]

Yes 2 mm or so,,Larry

[biffj]

I had a tail wag yesterday that seemed to be getting worse....I checked all the usual suspects and discovered the control horn on the servo was coming loose. I tightened the screw down and no more problem. There can be a lot of thing which cause vibrations in the heli and sometimes they aren't directly related to the axis involved. You might try checking the damper in the head and also the main blades in their holders. If they are too tight and can't swivel on the bolt than that sometimes causes either a vibration, a wobble of the whole machine or the infamous tail wag.

Good luck
Frank

[fast400]

Originally Posted by kmahler

I bought a used Blade 400. After replacing the main shaft because it was bent, I find that the tail vibrates. I checked the tail blades and they are exactly the same weight down to 100th of a gram.

This is my first larger than a Novus or mSR heli.

Kevin

check for a bent tailshaft,
then after running the screw`s back down on the tail case, back them off just alittle.
there is a problem with the brass spacer on the tail shaft not alway`s being the same length.
also make sure the boom is`nt bent, this could allow the belt to rub the inside of the boom and cause a vibration.
the pitch slider could be going bad, bearing`s in the tail case and or the front belt shaft`s bearings could be going bad.
even the oneway bearing sleeve in the lower main gear could be bent, this will cause a vibration because the bearings in the oneway are skipping over the bad spot.