How smooth can an IO360-M1A be?

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pietromarx
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Re: How smooth can an IO360-M1A be?

Post by pietromarx »

This is making me do some research.

The illustrated parts manualf (https://www.lycoming.com/sites/default/ ... 60-M1A.pdf) does not show counterweights anywhere.

Yet, according to Lycoming the engine has other components with dynamic balancing, whatever that means. This was discussed with the AD on certain counterweighted crankshafts (viewtopic.php?t=4739)

Lycoming has a rather defensive note on dynamic balancing that's worth a vague read: https://www.lycoming.com/content/what-engine-balancing

Per this: "Several Lycoming engine components are dynamically balanced. For non-engineers, that means that the proper balance is determined while the part is in motion; it is spinning as it would be during operation. These parts are the starter ring gear supports and the crankshaft. In addition, dynamic counterweights are statically balanced to control the location of the very critical center of gravity."

At the end of the day you have 279 lbs of engine and some amount of propeller weight bouncing around at the end of the airplane. It would be nice for it to be completely balanced (like, say, a turbine), but it is what it is.
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Charles K
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Re: How smooth can an IO360-M1A be?

Post by Charles K »

Reciprocating vs Turbine for sure - also just a 4 cylinder with big cylinders.
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Roxi5m9
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Re: How smooth can an IO360-M1A be?

Post by Roxi5m9 »

Thanks to everyone for the feedback. My motor is recently overhauled and has fine wire plugs and the timing is pretty solid, so another attempt at the balance, along with a better understanding of the nature of the lycoming Diamond combo I think will settle my nerves well to be content with how she runs.
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Rich
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Re: How smooth can an IO360-M1A be?

Post by Rich »

I thought I'd try a more in depth check on my plane's vibration in flight. At 2400 RPM there is no vibration through the seats, stick or anything else that I can normally note to my person. The only visible vibration is to the glare shield, and it's got an amplitude of maybe 1mm. If I place my hand on the instrument panel vibration is detectable by feel, but nowhere else visually. Frankly I don't know what more one could expect. I could put more damping on the glare shield, I suppose, but it's far from intrusive and only noticeable if you pay attention to it.
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Re: How smooth can an IO360-M1A be?

Post by Roxi5m9 »

That’s awesome feedback, Rich. And maybe the best answer to my original question of “how smooth can a DA40 be”. Of course a perfectly smooth airframe negates the most wear and tear, but like you said what more could someone expect. I’ll shoot for that. Thanks again.
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Re: How smooth can an IO360-M1A be?

Post by Rich »

There is one curious side note to all this. I've had my plane for over 16 years now. For all of those years, regardless of transitions between massive to fine-wire plugs, conversion to Powerflow, several of those 500-ish hour magneto reworks, mag timing checks, routine plug rotations, and a chunk of major engine work (about 3 years ago) it has always been true that, during mag checks:

Mag drop noticeably higher when on left mag than right, but engine remains as smooth as with both.
Running on right mag the engine is a bit rough.

I keep meaning to change out the mag harnesses, since that's the only constant in this whole thing.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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