Motor/Bearing Noise

Forrestt · Sep 27, 2016

Was doing pre-flight this morning and noticed this. The first motor I spin is silent the second one, well you'll hear. Decided to hover at about three feet and listen as well as watch for any abnormalities but she seemed to be ok. This definitely concerns me though. I didn't have her powered up or even a battery in it when I spun the props by hand.

Rayray · Sep 27, 2016

I listened twice, did not hear anything from the motors. Any idea what frequency range the sound is? I have high freq hearing loss, lol.

Brandon Lowe · Sep 27, 2016

Forrestt said:
Was doing pre-flight this morning and noticed this. The first motor I spin is silent the second one, well you'll hear. Decided to hover at about three feet and listen as well as watch for any abnormalities but she seemed to be ok. This definitely concerns me though. I didn't have her powered up or even a battery in it when I spun the props by hand.

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I could hear the sound. Can you try spinning the motor in the direction it runs and see if it still makes the sound?

gwhuntoon · Sep 27, 2016

I might have barely heard it. I've definitely heard bearing failure before which is usually a loud squeal. If it is bearing failure its probably not imminent. I would fly it that way until it got worse. If the motor does die, you have an H so it will fly on 5.

Forrestt · Sep 27, 2016

Brandon Lowe said:
I could hear the sound. Can you try spinning the motor in the direction it runs and see if it still makes the sound?

I tried cc &ccw. Makes the same sound.

rppr · Sep 27, 2016

If it was me: I would plan on spraying some electronics cleaner in the motor (spray can with straw...buy at autoparts store). Make sure everything is off and battery out. Wait few minutes to let the liquid evaporate. See if that works. If not, order new motor.

I say "plan" because I would call yuneec and ask 1) is this safe to spay and 2) is there a lubricant that is used in the motors that needs to be applied afterwards because the cleaner will clean it out. I've done this with RC car motors/parts. But those motors take a beating and designed for a bit of dirt and dust. But with this motor I don't know.

Steve Carr · Sep 27, 2016

Sounds to me like something inside the motor. Definitely not good. Take the bottom cover off the motor and try to blow compressed air through it to see if you can blow out any dirt, sand, etc. This does not sound like a bearing to me. If you can't get it cleared out then you need to take the motor apart and clean inside. Any tiny steel filings can stick to the magnets. BTW, the bearings are not sealed so it is possible to put a drop of 3-in-1 oil on each bearing and spin until the oil works it's way inside. Then use a Q-tip to remove any excess oil.

Innerworld · Sep 27, 2016

Try without the propellers, I guess then the sound is gone.
I believe this comes from the props mounts, they seem to 'wear off' somewhat, I have around 100 flights (same set of props)
and noticed this 'rattle' sound on a motor too, but when the props are off, the motor seem to turn fine. I haven't noticed any vibrations from it -yet- in my footage.
Guess that's the price for the quick release, in this cheapish plastic.. I think there are spare parts of the quick release plastic part on the motors.

PatR · Sep 27, 2016

rppr said:
If it was me: I would plan on spraying some electronics cleaner in the motor (spray can with straw...buy at autoparts store). Make sure everything is off and battery out. Wait few minutes to let the liquid evaporate. See if that works. If not, order new motor.

I say "plan" because I would call yuneec and ask 1) is this safe to spay and 2) is there a lubricant that is used in the motors that needs to be applied afterwards because the cleaner will clean it out. I've done this with RC car motors/parts. But those motors take a beating and designed for a bit of dirt and dust. But with this motor I don't know.

I would not even consider this action unless the motor was removed from the airframe. Electrical contact cleaner is quite destructive on some plastics and any excess that passes through the motor will go straight to the motor mount and LED lens cover. You could well end up causing more harm than good.

If you want to blow anything through the motor while in the mount, use a can of compressed air suitable for computers.

horizontal · Sep 27, 2016

Rayray said:
I listened twice, did not hear anything from the motors. Any idea what frequency range the sound is? I have high freq hearing loss, lol.

Dang Ray! I usually wear hearing aids but even without them in I can hear that. Watch out because we will be sneaking up to you when you are flying!!!

Forrestt · Sep 28, 2016

Thanks for everyone's input, I appreciate it.

Onthebrinc · Sep 28, 2016

I have the same problem with one of my motors. It will progresivly get louder and you will hear it in flight. Never found solution i will have to replace the motor.

Forrestt · Oct 4, 2016

Onthebrinc said:
I have the same problem with one of my motors. It will progresivly get louder and you will hear it in flight. Never found solution i will have to replace the motor.

Dragonflyerthom · Oct 4, 2016

Sounds like you have a bearing has gone out to me I don't know that any kind of lubrication would be able to solve that problem call Yuneec get an RMA fly safe

vr-pilot · Oct 4, 2016

Have a comparable sound (bearing dying?) on number 4: B-motor (rear right, white/silver). It started at about the 100th flight; I have now 203 flights and the other engines are doing fine...
I would continue to fly as long as it does not sound too obviously EOL (end of life) like.
When calculating my mean flight duration with 15 minutes, I would have just now about 50 hours of overall flight time with my YTH PRO RS. In real aviation this would mean check, lubrication and eventually replacement of moving parts.
How about inspection intervals for drones? (Replacing parts before they die and practicing some prevention would be a good idea IMO.)