Any ideas what causes this to a cylinder?

motoadve

motoadve

Pre-takeoff checklist
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May 12, 2009
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motoadve
O470R
Cyl, piston , rings 50 hrs since new
Strange pattern in cylinder and high oil burn, 1 quart per 2 hrs of flight.

Any ideas?
145411986_323533012375511_8657790434175147816_n.jpg
 
Not too common in my book.

“Ring Chatter” is what the cylinder shop called it.

The particular aircraft was a Lycoming 172 used for Fish Spotting.

Hours and hours of LOW power and low airspeed were routine.

I may have had to adjust Oil Pressure because it was was below Green Arc

at Low RPMs.
 
Magman said:
Not too common in my book.

“Ring Chatter” is what the cylinder shop called it.

The particular aircraft was a Lycoming 172 used for Fish Spotting.

Hours and hours of LOW power and low airspeed were routine.

I may have had to adjust Oil Pressure because it was was below Green Arc

at Low RPMs.
Click to expand...

Heard a lot about ring chatter in large radial engines, but you don’t hear about it much in flat GA pistons.
 
This is a sky diving airplane, run hard, going up and go down quick.
 
Fearless Tower said:
Well, if you were going to experience ring chatter in a flat engine, that would be the one

Always idle power descents?
Click to expand...
Idle descends, but why only one cylinder getting this?
 
Simple, the engine wasn't broke in correctly.

or

the rings are upside down.
 
Look at ring lands in the piston, or ring itself for more reconnaissance, if they’re not already too far gone for autopsy. You’ll have 5 other slugs to compare to.
 
Nothing to add except that has to be the cleanest cylinder I’ve ever seen.
 
At 50 hours some would argue it wasn't broken in yet, so I'll go with the "not broken in properly" answer.
 
I have read that ring chatter may have as one cause; prop driving the engine (flat prop, idle power, high airspeed)
 
Stewartb said:
At 50 hours some would argue it wasn't broken in yet, so I'll go with the "not broken in properly" answer.
Click to expand...
OR
The cylinder was not honed correctly.
 
Let'sgoflying! said:
I have read that ring chatter may have as one cause; prop driving the engine (flat prop, idle power, high airspeed)
Click to expand...
All that would create is low manifold pressure. That occurs every time the throttle is closed. not likely cause any damage.
 
Just curious-- how was that picture taken? Can a boroscope take one from that angle?
 
Let'sgoflying! said:
I have read that ring chatter may have as one cause; prop driving the engine (flat prop, idle power, high airspeed)
Click to expand...
I know it's a Continental in question here, but they use cylinders and pistons and rings just Lycoming does, and Lyc has this to say in their break-in Service Instruction:
DO NOT DO CLOSED THROTTLE DESCENTS. CLOSED THROTTLE OPERATION DURING DESCENTS WILL CAUSE RING FLUTTER WHICH CAN CAUSE DAMAGE TO THE CYLINDERS AND RINGS.

From https://www.lycoming.com/sites/defa...ating engine Break-In and Oil Consumption.pdf
 
Sam D said:
Just curious-- how was that picture taken? Can a boroscope take one from that angle?
Click to expand...
No, that was taken with the cylinder open.
 
Dan Thomas said:
I know it's a Continental in question here, but they use cylinders and pistons and rings just Lycoming does, and Lyc has this to say in their break-in Service Instruction:
DO NOT DO CLOSED THROTTLE DESCENTS. CLOSED THROTTLE OPERATION DURING DESCENTS WILL CAUSE RING FLUTTER WHICH CAN CAUSE DAMAGE TO THE CYLINDERS AND RINGS.

From https://www.lycoming.com/sites/default/files/Lycoming Reciprocating engine Break-In and Oil Consumption.pdf
Click to expand...
Are you certain the picture/cylinder we are looking at is ring "Flutter" I'm not.
 
motoadve said:
O470R
Cyl, piston , rings 50 hrs since new
Strange pattern in cylinder and high oil burn, 1 quart per 2 hrs of flight.

Any ideas?
145411986_323533012375511_8657790434175147816_n.jpg
Click to expand...
I'm not sure what we are looking at, but this pattern is more like a poor bore job.
typically cylinders are honed with a stone, but automotive bores use tool bits that leave tool marks very much this.
 
When you say 50 hours since new ... is that for all the cylinders or just this one? High oil burn sounds like the rings never seated because of improper honing or break in of the cylinder.

Seems strange if all the cylinders were done 50 hours ago and this is the only one that appears this way.

Perhaps the rings were incorrectly installed as mentioned earlier.
 
Is it actually 50 since ”new” or overhaul? I doubt a new cylinder wasn’t honed properly, but anythings possible. If new it should be covered under warranty. I think even a overhaul would be covered if it’s from a reputable shop. Your mechanic can probably get something worked out on that.
 
Last edited:
Tom-D said:
I'm not sure what we are looking at, but this pattern is more like a poor bore job.
typically cylinders are honed with a stone, but automotive bores use tool bits that leave tool marks very much this.
Click to expand...
I spent 12 years in a machine shop and did a lot of cylinder honing. Thousands of hours of it. Never saw any pattern like that. Ever. And I've never seen the the automotive-style boring machines used on aircraft cylinders. The small amount of metal removal doesn't justify it.
 
Dan Thomas said:
I spent 12 years in a machine shop and did a lot of cylinder honing. Thousands of hours of it. Never saw any pattern like that. Ever. And I've never seen the the automotive-style boring machines used on aircraft cylinders. The small amount of metal removal doesn't justify it.
Click to expand...
True.. It just looks likes the pattern left after a bore bar.
 
This cylinder doesn't like it has 50 hours on it.. way too clean.

Some thing is a miss, 2+2 isn't making 4.
 
You don't simply machine bore aircraft cylinders with a boring bar. The fins on the outside of the cylinder are machined thougyh.

I would look really hard on the ring and ring gap, and the piston ring lands. And is the spacing of the inside marking identical and correlated to the fins on the outside? Can you feel the grooves with your fingernail? Might it be a differential hardness associated with the machining of exterior fins? Note the spacing seems to be extended when the head is shrunk in the cylinder. That may be a clue to what's going on also.
 
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