914 servo motor chatter/buzzing

Hi Nicola,

I am sorry that non of our experts have responded to your enquiry.

I can only bring a small observation, from the automotive world - servos that  are unable to move due to electrical fault or a jammed component, (wastegate?) often click or buzz. Continued use usually sees the electrical components overheat /fail.😈

Does the servo perform the startup calibration movement? If it moves I would suggest there is a problem with the potentiometer wiper contact (dirt maybe or broken wiper). They tend to break at the tip. If it does not move, there is a possibility there is some mechanical blockage.

Thanks for reply.

Yes, it performs the usual calibration movement at startup.And with the right amplitude and movement as from the video in this channel.

We have another airplane at the airfield with a 914 engine

the plane is of the same type (tecnam P2002 sierra turbo) and age (aound 15 years old)

It has the same chatter/buzzing in the turbo servo

So i suspect that, with aging, internal wipers get oxydation / problems . A lot of times old (and above all unused)  rc (radio controlled models) servo has the same buzzing.

Are there other users of 914 engine that can check if the buzzing is normal?

thanks

Mine does like this

Is yours same or different? Mine was always like this - I haven't had it for a very long time, admittedly. I've known this to be normal. Should I worry?

Hi Dan,

I have a Europa XS with a 914.

A while ago my TCU servo was replaced with a brand-new one . The new servo buzzes and hums exactly like yours does, Dan.

Especially right after the initial calibration move. Sometimes the humming stops after I fully exercise my throttle once, without the engine running. 

Does a decent job otherwise and so far.

Best Thomas