Logo 700 elevator servo rocking back and forth

Hi Guys,

I had small crash with my logo 700. After rebuilding elevator servo rocking back and forth. I replace main shaft, main rotor yoke, main blades holder, spindle shaft, swashplate driver lever, entire head is new and the servo still rocking. Work fine just with the head with main blades holder but when I put
swashplate driver lever swashplate driver lever. I even bought 2 two new sets of swashplate driver lever and still have the same problem. Any advice/solution??

Thanks,
Pawel

Hi Pawel,

does the servo move on it's own, or how does it look?
If you swap servo connectors (e.g. CH1 elevator with CH2 aileron), does the issue persist only on CH1, or does it move to CH2?

Could be that the servo has taken damage, gears and/or potentiometer, so it can no longer re-center properly.

Maybe you can take a short video, upload it somewhere, and share a link?

Kind regards

Eddi

Born to fly ...
forced to work.

Hi Eddi,


Please see attached image The elevator servo link is moving back and forth. Like is said before when you spool motor up just with the head and blade arms is fine. But when you put swashplate driver lever the link is ocking back and forth. Hope that will explain better.

Thanks,
Pawel

Hi Pawel,

if it's moving back and forth, I'd assume a mechanical problem, the bolt not tight, the thread damaged, or even a bent main shaft or asymmetric yoke.

I mean, with the ball joint on the shaft, inner ring-outer ring having a tight connection, and the bolt set firmly into the rear arm of the swash plate, there is not back and forth possible whatsoever (in relation to the main shaft), the swash plate could could only rotate (without the guide) and obviously move up/town.

_But_ if the main shaft was not straight, the swash plate would circle with each revolution, and if the head yoke or swash plate driver arm(s) were not accurate to size, this could also cause an asymmetric rotation.

Is the old yoke still usable, for a test (just the yoke and the swash plate driver arms)?
What do you see if only one swash plate driver arm is connected (try both sides, both arms (or all four)?

It's a first to me, so I'd like to understand

Best,

Eddi

Born to fly ...
forced to work.

Hi Eddi,

There is no movement on the swashplate (no rocking back and forth) and up and down movement is perfect. Its is strange because entire head is new with main shaft. I even bought second main shaft because I was thinking the new shaft could be bend as well. Still the same. Very frustrating with this problem. I even replace all main bearings as well. Will do some video for you tomorrow if you don't mind?? Much appreciate for you help!!

Thanks,
Pawel

Hi Eddi,

The old yoke looks perfect and I still have it. To be hones I spend nearly 400€ replacing all the parts and the problem is still there. Never had problem with the heli till now. The crash was small. All i had to replace was blades, main shaft, autorotating gear and and just in case I replace spindle as well. Problem was still there and I start replacing all other parts just to be sure. After replacing all other parts problem still there so I thought I will het some help here

Thanks,
Pawel

Hi Pawel,

there's always a first time but if something is not running true, something must be bent out of shape or otherwise be damaged/faulty.

Go find it and let's see if we can tell something from a video.

Best,

Eddi

Born to fly ...
forced to work.

Hi Eddi,

Please see attached the videos. One without mixing arms(looks ok) no rocking back and forth on elevator link. Second one with mixing arms(looks not ok)
elevator link rocking back and forth. Entire head is new together with new mixing arms. Any idea now what caused it? Sorry I couldn't attached the file because is too big. Can you send me a email address so I can send you those video?

Thanks,
Pawel

Hi Pawel,

service (at) mikado-heli (dot) de

Kind regards

Eddi

Born to fly ...
forced to work.

Hi Eddi,


Wetransfer file with video is send. Hope we step closer to solving this problem

Thanks,
Pawel

Hi Pawel,

thank you. In the first video the inner ring is standing still, the main shaft is rotating inside the ball joint's ball.
All well, no movement, so the main shaft is straight.

In the second video, the inner ring is rotating, driven by the swash plate driver, and I can see that couple of 10th movement back and forth, not much, but still.

So I'd assume the inner ring of the swash plate is not running true, maybe the bearing is out of center a tiny tad, and if the swash plate was not replaced, it never was running true, must have been the same before.

If you want to have it repaired or replaced, please create a service request at www.vstabi.info/rma. It's not critical in my opinion, but of course everything running untrue causes extra vibration.

Kind regards

Eddi

Born to fly ...
forced to work.

Hi Eddi,

The swashplate wasn't replace. It's the original from the kit that I bought. Am I entitle to get replacement one when I create a service request??
Much appreciated for solving this problem.

Thanks,
Pawel

Hi Pawel,

we would like to check it here. Since parts can be replaced, we will either repair or replace, depending on what we find.

Kind regards

Eddi

Born to fly ...
forced to work.



Edited 1 time(s). Last edit at 12/20/2019 08:54AM by Eddi E. aus G..

Hi Eddi,

Just to give you updates. I bought new swashplate from Midland Helicopter shop and arrived today. I swapped the old one for the new one and I thought that the end of the issue but unfortunately the link still moving back and forth. I have no idea what to do now. I will test hover during the weekend. Like you said is no critical. Any new ideas how to solve it??


Thanks,
Pawel

Hi Eddi,

Did you seen my message above? Do you think is save to fly. One more question. I went trough the setup and all look good but when I touch cyclic stick i got message on Vtouch "the cyclic ring is active". Heli was on the bench and no binding noice form the servos. Do I need to be worry about it??


Thanks,
Pawel

Hi Eddie,

Another update. Was flying the Logo 700 yesterday. All seems to be ok at the moment. Elevator link still moving back and forth little bit but the heli flying good.

Thanks,
Pawel

Hi Pawel,

sorry for the late reply.

Regarding the swash plate, I consider it safe, as long as you don't get excess vibration because of it not running perfectly true. Even 2,000 rpm is not a considerably high frequency, anyway, it's only 33 Hz.

On the ground, if you move the cyclic stick, the VBar will try to move the model. But it does not react, so the VBar will increase the servo output to the max. eventually, and limit itself with it's built-in electronic cyclic limiter ring. Nothing to worry about, on the ground, but should not happen, and most probably never happens, in flight.

Kind regards

Eddi

Born to fly ...
forced to work.

Hi Eddi,

Sound good to me! Once again thanks for all your help.

Thanks,
Pawel