Vibration through entire plane

[FFSchooley]

The N3119Z saga continues. So when I bought the plane and flew it from Colorado, we noticed a mild vibration at full power cruise. Enough vibration that some of the knobs vibrated off. The motor checked out just fine, it pulls strong, makes correct power, and itself seems to run smooth. We hoped that proper rigging and removing the wheel pants would have fixed the vibration. Now that I am doing my flight training, I am using different power settings and am noticing this vibration to be pretty severe at lower RPMS. Around 2000-2400rpm, the vibration is severe enough to feel and see it in the yokes. I was wondering why I felt it in the yokes, and Yesterday during a flight noticed the wings tips were vibrating a bit, as were the ailerons. This wasn’t just the fabric drumming from airflow, the actual frame of the wing from about a few feet past the struts to the wing tips were vibrating up and down. I would say about a 1” deflection up and down, rhythmically to match what is felt in the yoke. I figured this vibration is Being transmitted through the controls. Question is, what would be causing a vibration through the airframe to the point the wings are vibrating? I’m guessing it’s a prop issue? I am having the prop overhauled and dynamically balanced in july, but am curious if anyone has seen this before and what actions I should consider to remedy it?

[Wag-builder]

I really hope what you are seeing is the vibration in the windows and the wings really are not moving. If it is the prop make sure it is clocked properly then take it off and rotate blade #2 to the position of blade #1 and see if that makes it any better. However, I would look really closely at the motor mount and the rubber mounts. Do you feel the vibration on the ground, or only in the air?

Steve

[dgapilot]

First thing I would do is get a vibration app for your phone and find out what frequency your vibration is. If it is prop rotation, or some multiple of prop rotation, then it is likely prop or engine related. Continuing to fly the airplane with vibrations like you describe will result in damage to the airframe in the form of cracks in the structure! Determine for sure if it is prop/engine related. Verify prop is installed correctly ( where it is on the hub and track) verify that you don’t have damage on the prop. Verify the spinner is running true with the prop. Having it overhauled is likely a good idea. When it is re-installed, dynamic balance is also a good idea.

If you can’t find an rpm range without vibration, best to do this right away before stuff starts breaking and you have more problems!


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[FFSchooley]

I only feel the vibration in the air. Yes, it’s the wings and not the windows. I will check the motor mounts and also get a vibration app and go from their I guess. I read the post about prop indexing. Right now it is clocked where it stops at 12 and 6. When I get it worked on I will have them index it to the horizontal position at #1 TDC.

I will film it next lesson so you can see what I’m seeing.

[Troy Hamon]

First thought is prop balance. I am concerned about the overall description though. Are you comfortable that there is absolutely no play in wing strut attachments when you shake the wings during a preflight? You should be push/pulling on the wing tip enough to shake the whole airplane, and when you do that, there should be no movement in the wing that isn't transmitted to the rest of the plane.

I would want to see the vibration in person, but if it is as significant as I am thinking based on your description, it should be addressed immediately.

Do you have an instructor that has any comment about the vibration?

[FFSchooley]

There doesn’t seem to be any play in the struts. I will confirm this next time I am at the hangar, but on preflight I push the struts up and down. Come to think of it though, I haven’t pushed the wings themselves up and down. I will check. I have looked at the engine mounts, but I will look more closely. Anything else I should be checking?

my instructor hadn’t said anything about it, I’m assuming he thinks it’s normal.

I have my next lesson schedule in 2 weeks and will film the vibration.

[andya]

On shutdown, my prop normally stops almost vertical. It is installed such that with the engine rotated
for TDC on #1 cylinder the prop is horizontal.

[Jim]

H,

I'd think a vibration as violent as you write should be investigated sooner than anytime later. Worse case, you might already have a broken engine mount. You mention you're having the prop yellow tagged and balanced. The engine and prop are a team that works best if they are balanced dynamically at the same runups. The shop doing a balance will clock your prop and spinner to a specific position and add, if needed, balance weights. Until something major happens, the prop and spinner will always be replaced exactly to where they were removed.

[akflyer]

Have a good AP check it out. Should be smooth. Vibrations like that would scare the crap out of me as it does not take long for them to do some major damage.

Is your mag check good? possibly dropping a cylinder? Does it change if you lean it out more?

[at7615]

Your prop should be clocked for hand propping, so facing the prop you should have the blades at approximately 8 and 2, #1 @ 0TDC. I would not continue flight without checking possibilities: prop? (May have internal corrosion/cracks) mounts? (the conicals and possibly metal broken) valves sticking? weak valve springs? (pull valve covers and check valves and tension of springs) Replaced a stuck lifter not long agoe on a 0-320- so they do wear out! Mags? (how long since inspection)