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Nylon vs Metal Locknuts

BH1166

BH1166

Well Known Member
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
 
Prop

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...
 
rocketman1988 said:
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...
Click to expand...

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

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.
 
BH1166 said:
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
Click to expand...

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

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,
 
rocketman1988 said:
Is the prop clocked in exactly the same position as before it was removed?
Click to expand...

Since I did not build, A&P did the work and I was there, and I asked to be sure it is placed back the same. Can I guarantee it was, nope. This has been my #1 thought as to the issue. Visiting A&P next week...we will discuss this. Thanks
 
Hey Butch,

Your problem is obviously the Bernie Warnke 72/72 prop; it's gone defective. Remove it immediately, and ship to:

Charlie England
140....

Oh, you're not going for that? Please. Please. PLEASE.....

Charlie
 
Mel is correct as to the nuts where and why.

Nothing more was done FWF as in the original post.

I agree, would not think nylon to metal as a complete change out would be an issue, I trust you all in this question.

I will check on the spinner and see if there is a way it could indeed be some filler in a new spot since reattached during bolt change out.

Yep, there were washers, did they all get put back on...hmmm, not sure and I WILL check.

This vibration is like the new oil spot in your concrete driveway that was not there yesterday. Not a serious thing, but sure as heck is new and I liked it better the other way!

WOW ! Thanks folks...amazing group...ask and he shall receive. :D
 
rv7charlie said:
Hey Butch,

Your problem is obviously the Bernie Warnke 72/72 prop; it's gone defective. Remove it immediately, and ship to:

Charlie England
140....

Oh, you're not going for that? Please. Please. PLEASE.....
Click to expand...

You tried Charlie ! It is NOT a climb prop, but it is one heck of a cruise prop. I live and fly in flat land, solo. I thought I wanted another prop, but the cruise performance spoils you quick.
 
You're preaching to the choir; I have what's left of one exactly like it in my hangar (a/c partner pranged it a couple of decades ago). I never managed to get a duplicate from Bernie; I think it was near the end of his career. I can tell you that if you go to the typical 68" dia from anyone, you'll lose climb performance & you won't gain anything at all on the top end. Mine was magic.

If you ever decide to sell it, please give me 1st refusal. :)

Charlie
 
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