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Old 01-16-2017, 07:40 AM
bernsbm bernsbm is offline
Join Date: Nov 2015
Location: Mequon, WI
Posts: 23
Default Advice needed

Hi Everyone. I'm having a problem with my RV12 and am looking for some thoughts on how to resolve it. Some background first. My RV12 E-LSA is a Synergy Air quick built kit started in April 2016 and completed in Sept 2016. First flight was in October 2016. I now have ~30 hours on the plane, and love the way it flies. However, I have a disturbing low frequency vibration, almost a hum, the source of which I've been unable to isolate. I can easily feel it in the rudder pedals, engine controls, instrument panel and canopy.

Other observations:
Occurs at all engine RPMs, may be a little worse between 3000-4000 RPM
Occurs at all airspeeds while airborne
Is NOT present at any RPM while on the ground

Attempts to correct:
Pitched prop blades, identical to 0.1 degree
Carbs balanced by experienced Rotax repairman
Carb floats checked and all found to be ok (2.9gm each)
Gear box removed, checked and reshimmed to Rotax specs
Removed nose wheel fairing (no difference noted)
25 hour Rotax inspection completed with no problems found
Prop dynamically balanced
Checked Engine Isolators per Van's Notification 16-08-10 and found to be correct.
Prop blades returned to Sensenich and balance checked

Any thoughts on where else to look for the source of a bothersome vibration, neither airspeed or RPM dependent, only present while airborne?

Help much appreciated!

Mequon, WI
2017 Dues Happily Paid
RV12 Flying
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Old 01-16-2017, 08:05 AM
JBPILOT JBPILOT is online now
Join Date: Nov 2007
Location: Jesup, Iowa
Posts: 1,586
Default Basic question - -

Have you flown in other RV-12's ?
John Bender
Flying RV-12 - Serial #120036
Paid in May ( 5-4-18 )
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Old 01-16-2017, 08:17 AM
Tony_T's Avatar
Tony_T Tony_T is offline
Join Date: Dec 2008
Location: Lacey, WA
Posts: 1,204

Is the nose wheel balanced? It could be turning in flight. I doubt the mains will turn in flight because of disc brake drag.
RV-12 #202 -- Flying
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Old 01-16-2017, 08:21 AM
bernsbm bernsbm is offline
Join Date: Nov 2015
Location: Mequon, WI
Posts: 23

Yes, I did my transition training in an S-LSA. Didn't feel anything like the vibration in my 12.
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Old 01-16-2017, 08:25 AM
Piper J3's Avatar
Piper J3 Piper J3 is offline
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 876

Maybe its shivering in the cold...
Jim Stricker
Hinckley, Ohio
PPL/ASEL 1970 Sport Pilot since 2004
80 hrs Flying Aeronca Chief 11AC
1130 hrs Flying 46 Piper J-3 Cub
RV-12 E-LSA #120058 AWC Jul 2012 - Bought Flying Oct 2015 with 48TT - Hobbs now 350

LSRM-A Certificate 2016
Special Thanks to EJ Trucks
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Old 01-16-2017, 08:35 AM
DHeal DHeal is online now
Join Date: Sep 2006
Location: Windsor, California
Posts: 679

Could it be noise associated with airstream leakage? I assume your Synergy RV-12 was equipped with Van's canopy weather-proofing / sealing kit?
David Heal - Windsor, CA (near Santa Rosa)
EAA #23982 - EAA Technical Counselor and Flight Advisor; CFI - A&I
RV-12 E-LSA #120496 (SV w/ AP and ADS-B) - N124DH flying since March 2014 - 640+ hours (as of June 2018)!
VAF donation through June 2019.
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Old 01-16-2017, 08:52 AM
John-G John-G is offline
Join Date: Jan 2012
Location: Northeast Ohio
Posts: 493

+1 for what Tony suggested. I think Tony may be on to something .... I've seen videos where the nose wheel spins while in the air. A spinning wheel not balanced would certainly induce a vibration into the air frame.

I would take the nose wheel off and check to make sure it is balanced as best as possible.
RV-12 Wings, Empennage, Fuselage, Finishing, Avionics and Powerplant kits all completed
Now Flying!!

Dues paid until September 2018

Last edited by John-G : 01-16-2017 at 08:52 AM. Reason: spelling
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Old 01-16-2017, 11:13 AM
JBPILOT JBPILOT is online now
Join Date: Nov 2007
Location: Jesup, Iowa
Posts: 1,586
Default I had the front nose wheel 'problem' - -

I needed to add a little more toque on the front axle bolt. The wheel was spinning ( with wheel pant ). No noise, just a low freq vibration. Once the wheel stopped spinning in flight, went away.
John Bender
Flying RV-12 - Serial #120036
Paid in May ( 5-4-18 )
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Old 01-16-2017, 11:44 AM
jeterjim jeterjim is offline
Join Date: Dec 2009
Location: Orange Beach, AL
Posts: 24

From first start to about 35hrs I had a vibration noise. I search all kinds of places from engine to tail trying to figure out the problem. Noise was more of a hum on the ground and got worst at 3500-4000 rpm. While flying with my son I was in the right seat. He suggested I lean my foot against the aircraft skin just next to the rudder pedal. Sound stopped. I installed a stiffener and haven't had a problem since. Nothing to loose in looking at that area.
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Old 01-16-2017, 03:04 PM
scottmillhouse's Avatar
scottmillhouse scottmillhouse is offline
Join Date: Apr 2007
Location: Madison, AL
Posts: 205

I had noises that I determined came from the instrument panel shelf, below the glove box and also some from the rear baggage bulkhead cover. Went to the Home Depot aviation store and bought a 3" wide roll of stick on insulation foam that is foil backed. (used for water line insulation) I put strips on panel shelf under glove box and that noise disappeared. Likewise for the baggage panel cover where I put it between the corrugations. Only a couple of $ and a few ounces for an easy fix. Still great after 100 hours.
Scott- 2018 dues paid
Got medical back, now building a 7A.
RV-12 #120515, 319RV over 235 hours.
1st flight 12/08/15, flew SNF, Oshkosh, Triple Tree & SERFI in year 1!
RV-9A, 536 hours, sold, RV-7 sold, Kitfox sold
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