700 Tail blades out of track

[Rctintin]

While checking for everything that could have caused my sudden tail vibration, I put a piece of red tape on one of the tail blades and then spun the head (with the main blades off) fast by hand. There is about 2 mm difference in the track of the tail blades. The only way that can be is if the tail grip holder is out of square to the out put shaft. Has anyone else found this?

I have fitted 4 of these tail push rod guides: Fast Lad Performance and to be honest, I'm not that impressed with them! They scratch the boom quite bad when fitting them, and they don't grip the boom very well either. I have had to put a wrap of tape around the boom to get them to fit better. I think I will go back to the std ones if these move in flight, so they were a waste of 20 quid!

I have checked all of the tail bearings, TT bearings, and all is fine, so I'm no nearer to finding the cause. It does seem to be a high frequency vibration, the fuel is going crazy at half tank, where as before, it was very calm once the fuel level dropped and the pressure 'blast' was not disturbing the fuel.

Could this just be engine tuning? She is still quite rich, as you can see oil drips being blown from the exhaust. It does seem to bog down a bit on fast climb outs, and then I'm getting some over speed on the way back down. Should I limit the pitch range to +/-10% as I wont be using more than that, and it should help the engine loading. This is with a govner on and at 1850 HS.

Any help or suggestions would be gratefully received, cheers Rob.

[0h5h1t]

tail out of true - check output shaft and tail hub.. the hubs bend if the tail so much as looks at the ground hard... lol

headspeed increases on way down - check governor is actually working as the head speed should not increase.. it could be that the governor is not working and the heli is flying on throttle curves. check sensor and magnets etc too.

a rich engine will/can cause tail wags so it is worth tuning the engine to exclude it. check your plug as well.

the loading/bogging is probably caused by engine tuning too. you don't say what engine/pipe or governor you are using or your flying style so I can't be more helpful I'm afraid.

[electricsceadu]

a bent hub and tail output shaft will cause it to be out of track
pls check that the bearings are perfect (a hard job with align chocolate bearings)
also look at the links between the tail blade holder and the tail pitch slider if they aren't the same length then they won't track

[Rctintin]

The tail links are the KDE upgrade ballraced alloy ones, so should be same length.

I've had no hard landings, and no bumps at all.

Engine is YS91 on a Hatori pipe, using 20% optifuel.

Flying style is smooth, big '8's and circuits, no SB'ing yet for me!

Govner is Align one in LE kit.

[Rctintin]

Had another look tonight, and the tail blade grip holder axle can move around on the output shaft if the grub screw is loose. Now I know, it wont be loose, but the problem seems to be that when the grub screw is nipped up, the axle moves away from 90 deg to the shaft. It is as though the hole through it is to large, and it can move around on the shaft. If I just nip the grub screw up enough to spin the tail via the head, then it tracks true, but when you then tighten up the grub screw, it pulls it out of line, and the tail blades are out of track.

HELP!

[Rctintin]

Any ideas guys? How do I get a straight tail?