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  #1  
Old 01-05-2019, 03:50 PM
stneki stneki is offline
 
Join Date: Feb 2006
Location: Spring Lake, MI
Posts: 149
Default Vibration

I have 125 hours on my RV7A with an Aero Sport 0-360 ECI engine. The prop is a Sensenich metal prop purchased through Vans. During take off and level flight I have a vibration. When decending it is not near as noticeable. I had the prop dynamicaly balanced. It seams to be better when lean of peak. Leak down and regular compression testing show good. Ignition is a Light Speed II and one mag. Timing is set correct. Carb was just overhauled. Any ideas or suggestions?
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  #2  
Old 01-05-2019, 05:42 PM
BobRv4 BobRv4 is offline
 
Join Date: Nov 2012
Location: Gilbert, AZ
Posts: 124
Default prop

try repositioning the prop on the crank. Bring #1 cyl to TDC, the prop should be at about 1 o-clock. If the vibration goes away at zero thrust (in a decent) you may have different pitch on the blades. Try checking with a protractor. Also check the track of the blade at the tips.
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  #3  
Old 01-05-2019, 05:49 PM
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rocketbob rocketbob is offline
 
Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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Check for baffle aluminum too close to the cowling, making the interface stiff. I see this often.
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Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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  #4  
Old 01-06-2019, 05:42 AM
alcladrv alcladrv is offline
 
Join Date: Oct 2006
Location: Southeast
Posts: 569
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Bob,

What's a good spacing to shoot for between the aluminum baffle and the inside of the cowl?

Thanks
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  #5  
Old 01-06-2019, 05:57 AM
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chepburn chepburn is offline
 
Join Date: Apr 2006
Location: Ottawa , Canada
Posts: 224
Default

Check your exhaust hangars as well.

They can come loose and that will create the vibration you are describing.

(It happened to me... your description matched my aircraft's symptoms)
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  #6  
Old 01-06-2019, 07:15 AM
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rocketbob rocketbob is offline
 
Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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Quote:
Originally Posted by alcladrv View Post
Bob,

What's a good spacing to shoot for between the aluminum baffle and the inside of the cowl?

Thanks
1" with McFarlane baffle material.
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Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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  #7  
Old 01-06-2019, 07:17 AM
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rocketbob rocketbob is offline
 
Join Date: Jun 2006
Location: 8I3
Posts: 3,564
Default

Quote:
Originally Posted by chepburn View Post
Check your exhaust hangars as well.

They can come loose and that will create the vibration you are describing.

(It happened to me... your description matched my aircraft's symptoms)
Its best to hang the exhaust off the engine and not have hangers attached to engine mounts.
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Please don't PM me! Email only!

Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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  #8  
Old 01-06-2019, 07:58 PM
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airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 5,145
Default

Speed-dependent vibration may be something other than engine/prop - look for a loose wheel fairing that will resonant at certain airspeeds or angles of attack and play nicely at others. I've had it once on my left main as a screw worked its way through the fiberglass and lost grip.
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Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
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  #9  
Old 01-06-2019, 08:19 PM
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fl-mike fl-mike is offline
 
Join Date: Jul 2005
Posts: 1,346
Default

Check for a ?shaky leg?.
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RV-6A. Mattituck TMX O-360, FP, GRT Sport EFIS, L3 Lynx NGT-9000
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N184WM reserved (RV-8)....finishing kit in progress. Titan IOX-370
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