Nylon vs Metal Locknuts

[BH1166]

During recent conditional, prop bolts and nuts were all replaced. Changed from nylon to metal locknuts. This was the only thing changed FWF. I now have vibrations that I did not have before. Only I would feel the new vibrations. I feel them in my feet and can see more "wiggle" in Ram Mount(ed) items in cockpit. Not banging around, but sure feels different to me.

QUESTION: do you think going from Nylon to Metal is enough change to make this happen, a balance change?

My setup

Lycoming O320
Bernie Warnke Almost constant speed wood 72x72 prop
Mark Landoll Harmonic Dampener

[rocketman1988]

Is the prop clocked in exactly the same position as before it was removed?

If it is off even one hole, it could make a difference...

[lr172]

Originally Posted by rocketman1988

Is the prop clocked in exactly the same position as before it was removed?

If it is off even one hole, it could make a difference...

That is my guess as well. Weight differences between nuts shouldn't make a difference unless there were meaningfull variances in individual nut weights between old and new. If the delta weight between each nut (old vs new) is the same, it should have no impact.

Is your spinner labelled. If your spinner has any type of filler or epoxy added to it, it will give different balance characteristics when installed in its two potential positions. My spinner is marked on the inside with an A and B side to be sure it goes on the same way each time.

Larry

[scsmith]

First thought was to re-balance the prop.

But a hairbrained idea did flash across my mind. Could a whole bunch of elastomeric lock washers on rotating hardware add up a hint of damping?....

No, the nuts better be tight, so the nylon locking feature can't possibly feel any displacement.

[BobTurner]

Did you add the drag torque of the locknuts to the recommended fastening torque?

[Raymo]

Maybe a dumb question but why do you have nuts on the back of your prop flange? There should be inserts in the flange.

[scsmith]

Originally Posted by Raymo

Maybe a dumb question but why do you have nuts on the back of your prop flange? There should be inserts in the flange.

The Continental O-470 on my 182 has locknuts on the back of the prop flange. I've never seen a Lycoming without inserts, but I have not looked at that many. Maybe some didn't use them?

Interestingly enough, the spec'ed locknuts for the C-182 prop are Nyloks.

[skylor]

Originally Posted by BH1166

During recent conditional, prop bolts and nuts were all replaced. Changed from nylon to metal locknuts. This was the only thing changed FWF. I now have vibrations that I did not have before. Only I would feel the new vibrations. I feel them in my feet and can see more "wiggle" in Ram Mount(ed) items in cockpit. Not banging around, but sure feels different to me.

QUESTION: do you think going from Nylon to Metal is enough change to make this happen, a balance change?

My setup

Lycoming O320
Bernie Warnke Almost constant speed wood 72x72 prop
Mark Landoll Harmonic Dampener

You said you performed this work during a recent condition inspection? Is it possible that the vibration isn't from the prop at all but something else that changed during the inspection? Perhaps the exhaust pipes were moved or you have a broken exhaust hanger, or maybe a baffle seal is inside out and vibrating? Also check to make sure your spinner is still running true since it was likely removed and reinstalled.

Skylor

[maniago]

What about washers? Did you maybe leave one off in the change out? Eitherway, if you find nothing and it still bothers you, revert back to nylocks and see what you get.....

[Mel]

Originally Posted by Raymo

Maybe a dumb question but why do you have nuts on the back of your prop flange? There should be inserts in the flange.

He never said they were on the backside of the prop flange. Using a F/P prop on an RV, the extension bolts to the prop flange. The prop bolts have nuts on the backside of the extension flange,