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  #1  
Old 07-12-2015, 12:29 PM
JPalese's Avatar
JPalese JPalese is offline
 
Join Date: Apr 2011
Location: KHXF
Posts: 143
Default RV-12 Vibration

Not sure if this belongs here or in the RV-12 section . . . .

Flew an S-LSA RV-12 the other day and there was a short yet pronounced vibration that even seemed to affect the arc of the prop spinner (appeared to be ecentric during the life of the vibration).

The owner told me the vibration was short lived and consistently occurred about 250' AGL on takeoff.

We were able to determine that the vibration occurred as the nose wheel spun down to "0" RPM.

This was determined by doing a touch and go while keeping the nose wheel off the pavement - no vibration whatsoever.

Any one else experience this?

Any thoughts or recommendations as to a cure?
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  #2  
Old 07-12-2015, 12:46 PM
JBPILOT JBPILOT is offline
 
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Location: Jesup, Iowa
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Default Likely - -

Torque on front axle bolt is too low. Wheel is spinning too freely. Also might be out of balance. Both can be a problem.
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  #3  
Old 07-12-2015, 02:38 PM
Tom Delaney Tom Delaney is offline
 
Join Date: Dec 2007
Location: St. Louis, MO
Posts: 155
Default Wheel pants?

If so, you might try a flight without the nose wheel pants, if all else fails.
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  #4  
Old 07-12-2015, 04:51 PM
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rvbuilder2002 rvbuilder2002 is offline
 
Join Date: Jul 2005
Location: Hubbard Oregon
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Default

Quote:
Originally Posted by JBPILOT View Post
Torque on front axle bolt is too low. Wheel is spinning too freely. Also might be out of balance. Both can be a problem.
Actually, the type of bearings in the RV-12 nose wheel do not / should not develop any appreciable preload friction from tightening the axle bolt. If tightened enough that it does, it is loading this type of bearing in a way it is not intended to be.
Balancing the nose wheel assembly should resolve the problem.


PS
It might be more appropriate if this was in the RV-12 section (if a mod agrees and could move it).
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  #5  
Old 07-12-2015, 07:14 PM
JBPILOT JBPILOT is offline
 
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Location: Jesup, Iowa
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Default Scott - -

My front wheel was spinning freely with just the wind blowing on it with wheel pants. I torqued the axle bolt a little, and it added just a little friction and it stopped spinning while flying. Balancing helped me the most, but I had both problems, and doing both solved it.
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