Vibration is stripping my servos out

[Matt Sherman]

I am running a YS 96 ( converted from a 91 ) on my N7 and I got some kind of vibration coming from the motor or somewhere else that keeps stripping out my BK servo's. The servo motor uses a brass gear and that's what keeps stripping out. I guess I'm going to have to drop the motor and check the front and rear bearings. It has been crashed before so maybe the torque tube could be slightly bent and could be causing the vibration? Anyone ever heard of this problem?

[ChadCarlin]

It could be any number of things. Are you saying its coming from the engine because you saw this on vibration analysis? Are you using the rubber grommets on the servos?

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[Ah Clem]

" Are you using the rubber grommets on the servos?"

That would be my question too.

In 40 years, I have never seen vibration strip the gears in a helicopter-even plastic ones. I have seen air-loads, crashes, etc. do it, but not vibration.

[Matt Sherman]

I don't know what else it could be coming from if not the motor. I am using the rubber grommets.

[ChadCarlin]

Could be engine bearings, clutch stack balance, bearings in clutch stack, bearings anywhere on the heli, bent shafts, loose muffler, loose engine mounts....

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[Rodney Kirstine]

I'm guessing your FBL controller doesn't have vibration analysis?

[Ah Clem]

"I'm guessing your FBL controller doesn't have vibration analysis?"

Excellent point!

I would think that if the vibration was bad enough to strip the servo gears, the FBL unit (no matter which one) would be so unable to cope with it that the machine would be unflyable.

I am very interested in what is ultimately determined to be the route cause of this.

[Rodney Kirstine]

Any time I've had a bad vibration it's always manifested itself in the model wanting to roll really bad.

Which servo, or servos are getting their gears stripped?

[Matt Sherman]

I am using the spartan so don't think it has analysis. The servo's are BK. The FBL unit works fine. I'm just going to have to start tearing it apart and see if I can find the problem. I am a little suspicious of the clutch stack because I started using the Sullivan one way starter shaft and the shafts on these never really come perfectly straight and it may have wore out the clutch stack bearing.

Also had several of the BK servo wires come de- soldered from the board and when I talked to Bert he more or less blamed it on the YS. He did replace them however.

[Matt Sherman]

One other thing I should mention is I am running my Hatori with only one of the black o-rings and not 2 because one ripped on me. I thought it would be alright to run until I got another o-ring. Maybe it's possible that's causing the problem?

[ChadCarlin]

If the vibes are bad enough to break a servo they should be also affecting the fbl unit.

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[Rodney Kirstine]

Do you see a lot of foaming in your fuel tank? It would be interesting to see (and hear) some video of your engine running. A bad tune can definitely cause some nasty vibrations. Also, only having the one O-ring on that pipe header is definitely not helping.

[Matt Sherman]

The heli is down right now because the servo caused it to crash. I'm thinking about buying a whole new motor and starting fresh.

[Rodney Kirstine]

Bummer.

[Danny Dugger]

Was the main shaft collar tight? If that is left loose it will slip under the swash in flight and bind your servos. Will cause nasty noises, vibration, and stripped servos. Easy to tell by looking under the swash to see if it's beat up. Don't ask me how I know. :rolleyes:

[Matt Sherman]

I will check but I'm pretty sure it's good.

[Matt Sherman]

What kind of servos do y'all run on your N7?

[smwht]

Xpert r1s in mine. They're a snug fit because of the removable servo lead if you run the grommets, though.

[Danny Dugger]

I've got torq on mine because I had them on hand... MKS or Futaba are my go-to servos for everything.

[narcisstking]

MKS all day everyday.

Cheers!