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Old 09-01-2020, 12:28 PM
BillL BillL is online now
Join Date: Sep 2007
Location: Central IL
Posts: 5,891
Default IO-540-D4A5 Whine??

Many aircraft engines have their own distinctive sound.

Does the IO-540-D4A5 have a distinctive whine, maybe a gear train sound?

I heard my friend's 10 fly over a couple of weeks ago and heard a whine. It was distinctive and thought it sounded like a gear sound.

He independently brought the subject up a week later and is now fixated on finding the cause after his wife asked about "that sound". I am just polling the braintrust to see if it is a known sound.

How many teeth are on the crank driver gear? That should help identify the frequency.

Final Edit: Problem solved: See post #22

Lord Kelvin:
ďI often say that when you can measure what you are speaking about,
and express it in numbers, you know something about it; but when you
cannot measure it, when you cannot express it in numbers, your knowledge
is of a meager and unsatisfactory kind.Ē

Last edited by BillL : 09-05-2020 at 03:59 PM.
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Old 09-01-2020, 12:46 PM
Electrogunner Electrogunner is offline
Join Date: Aug 2016
Location: Quarryville ,pa
Posts: 560

The only whine I ever have is in cold weather on start up for a couple minutes. Was told and read it's from cold oil going through the oil cooler.
RV10 N620RV
IO540 C4B5
Whirlwind 375RV prop
Garmin G900X
First Flight 2/14/2019
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Old 09-01-2020, 12:54 PM
BobTurner BobTurner is offline
Join Date: Dec 2011
Location: Livermore, CA
Posts: 7,356

I always thought mine had some sort of gear train sound. I thought it was just me.
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Old 09-01-2020, 01:09 PM
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aturner aturner is offline
Join Date: Jan 2005
Location: Clarion, Pennsylvania
Posts: 566

Bill, I occasionally get a significant whine from my engine, as you describe, and it really bugged me for a long time. Heard at taxi power (but only occasionally) probably present at higher power settings but not loud enough to hear. Comes and goes. I chased all sorts of leads, with no luck, and then one day reached up with my foot and pressed it against the firewall. Whine stopped. Something from the engine (accessory case gears? Oil cooler?) is setting up a vibration that resonates with the firewall. The sound is unsettling, but I felt better once I understood that most of it was coming from the vibrating firewall. I also havenít heard it much in the past year or two.

Like to hear the thoughts / experiences of others.
-Andy Turner
RV-10 N784JC
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Old 09-01-2020, 01:50 PM
AlpineYoda AlpineYoda is offline
Join Date: Nov 2019
Location: Boulder, CO
Posts: 274

If it comes from a harmonic in the firewall, is it possible to attach some kind of foam or other material to reduce the vibration? If your foot can stop it, it seems like some kind of sound absorbing / vibration absorbing material should be able to take care of it.
RV-10 build blog --
Started 12/19/2019
Engine hung 1/9/2021
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Old 09-01-2020, 04:30 PM
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Bill.Peyton Bill.Peyton is offline
Join Date: Sep 2009
Location: St. Louis, MO
Posts: 1,828

I too have a whine. Much worse when engine is hot. Occurs in the 900 to 1200 rpm range. It is amplified by the firewall and oil cooler. I bypassed the cooler and it disappears. I removed the oil cooler from the firewall and it disappears.

I replaced the vernatherm, the oil cooler and both hoses to the cooler and it temporarily went away, but 30 hours later itís now back. I spoke with an old guy who used to own an engine shop and he told me that it was a common problem and it just a resonance set up by the spinning oil pump gears. He suggested changing the length of the oil cooler lines.

Iíve learned to ignore it.
Bill Peyton
RV-10 - 1125 hrs
First Flight Oct 2012
Aviation Partners, LLC
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Old 09-01-2020, 04:40 PM
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RV10inOz RV10inOz is offline
Join Date: May 2008
Location: Brisbane Qld. Aust.
Posts: 2,304

You would not hear the normal whine you get taxiing from a plane overhead. That is a different air noise you are hearing from the ground, and that is normal too.

David Brown

DYNON Authorised Dealer and Installer

The two best investments you can make, by any financial test, an EMS and APS!
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Old 09-01-2020, 06:19 PM
AIR HOG AIR HOG is offline
Join Date: Sep 2018
Location: Bumpass, VA
Posts: 16

Does it sound like this?
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Old 09-01-2020, 06:41 PM
kkmarshall kkmarshall is offline
Join Date: Sep 2014
Location: Central Tx
Posts: 197

I get a whine for a few minutes when starting in cooler/cold weather. Doesnít happen when preheated.
329DR RV10-bought flying
Continually upgrading/tweaking
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Old 09-01-2020, 06:52 PM
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aturner aturner is offline
Join Date: Jan 2005
Location: Clarion, Pennsylvania
Posts: 566

Bill, thank-you for the good information. Same symptoms as my noise, and Iíve also been playing with the oil lines (though not to the extent you have!). It puts my mind at ease knowing it is a common issue and not likely a problem. Thanks.
-Andy Turner
RV-10 N784JC
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