strange tail problem after crash

[redsoper]

replaced everything that was broken or bent after the crash, the tail works on the bench. but at the field at about about half power (mid-stick) the servo is not moving, heli wants to spin, servo is a mks 669. went through setup on beastx everything is moving in the right direction, i checked the wires and leading edge control everything looks good. kinda stumped now, thinking its the servo just don't want to get a new one till I rule out everything. got any tips or anything guys?

[Ah Clem]

When you rotate the helicopter on the bench, does the trailing edge of the tail blades move in the direction that the tail is moving (i.e. if you move the tail to the right, do the trailing edges of the tail blades move/point to the right?)?

[redsoper]

Originally Posted by Ah Clem

When you rotate the helicopter on the bench, does the trailing edge of the tail blades move in the direction that the tail is moving (i.e. if you move the tail to the right, do the trailing edges of the tail blades move/point to the right?)?

if I move it to the right it goes left

[TheBum]

That's your problem then. In that case, the gyro is not countering the torque, it's aiding it. Did you have to replace parts in the tail rotor or slider area? Speaking from personal experience, if you don't pay attention, it's easy to get things flipped around during reassembly. The tail blade grips should have the links on the leading edge side of the blades.

[redsoper]

took a picture of my tail, still got the same problem, no tail control or tail movent at half power

[TheBum]

That looks right. Is it possible the tail servo may have stripped gears? Or a stripped spline on the servo arm? If the movement is OK until the heli reaches a certain head speed, then that would indicate to me a servo issue.

[redsoper]

gears are not stripped. i think its the motor it cant handle a load anymore anybody know who repairs mks servos?

[dannylightning]

Originally Posted by redsoper

gears are not stripped. i think its the motor it cant handle a load anymore anybody know who repairs mks servos?

go to the mks servo usa website, you fill out a contact form and they will email you a form you fill out and send into them along with your broken servo..

[Rob43]

I had an Align servo which wouldn't stroke past 1/2 way. I saw no damage to gears inside, but I replaced all of them, plus output shaft bearings and it worked perfectly. But mine wouldn't work on the bench either, so I guess that's not what is going on in your case. Might be your sensor isn't working properly when in flight.

[Primal]

Did you get this sorted out?

We had exactly the same thing happen on my friends 550x after a crash. Worked fine on bench but stop working under power. Turned out to be a slightly damaged tail thrust bearing. It worked fine with no load but under power it would seize up.

[redsoper]

I order a new servo, didn't want to wait for the mks to be repaired, my flying season is almost over, it starts snowing around September and sticking to the ground in October

[salmonson63]

This sounds exactly like a bad thrust bearing in the tail grip. When a thrust bearing goes bad you will be able to move the tail fine on the bench since the grips are just relying on the radial bearings. But when you start to spool up the heli there is hundreds of pounds of force on the grips. At this point the grips are now relying on the thrust bearings to be able to rotate. So unless you can apply hundreds of pounds (around 350 if I remember right for this model) to the grips this problem will not show itself on the bench. I have had this happen on a different model and was very surprised when I discovered a thrust bearing was the cause of this.

Hope this helps.

[redsoper]

got her in the air and she is flying good thanks everyone, I think it might have been the thrust bearings, I will put the mks tail servo on tomorrow and see what happens

[electronjunkie]

Originally Posted by salmonson63

This sounds exactly like a bad thrust bearing in the tail grip. When a thrust bearing goes bad you will be able to move the tail fine on the bench since the grips are just relying on the radial bearings. But when you start to spool up the heli there is hundreds of pounds of force on the grips. At this point the grips are now relying on the thrust bearings to be able to rotate. So unless you can apply hundreds of pounds (around 350 if I remember right for this model) to the grips this problem will not show itself on the bench. I have had this happen on a different model and was very surprised when I discovered a thrust bearing was the cause of this.

Hope this helps.

I hopped on here to suggest the same thing! Been there before.