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  #1  
Old 03-01-2016, 09:41 PM
MartinPred's Avatar
MartinPred MartinPred is offline
 
Join Date: Nov 2005
Location: Overseas
Posts: 158
Default Making a Little Bit of Metal

So over the past two years, the iron in my oil samples has been slowly creeping up. But the filter was always clean so I just kept an eye on it.

On my last oil change however, I was able to tease a little bit of ferrous particles out of the filter with a magnet.

The engine is a Lycoming O-360-A1D with Bendix mags, about 600 hours since factory re-man.

Here's the oil data:



Filter at first glance looks pretty clean:



But with a magnet, I'm able to pull out tiny ferrous particles:



The engine has been running great. And I watch my CHTs like a hawk. Here's a recent flight:



Blackstone still thinks it's not urgent, and recommends checking back in 30 hours. But I did find something that was worrisome--a possible crack in the engine mount:



Hard to tell if the crack goes through the paint or not. But the fact that it runs along the tube has me worried. Could vibration also cause some wear inside the engine?

At this point, I'm inclined to take Blackstone's advice. But I'd love to hear the thoughts of the engine guys out there.

-Matt
N402BD
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  #2  
Old 03-01-2016, 10:03 PM
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airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
Posts: 5,815
Default

Could be the picture, but that looks more like a rub mark from something than a crack on the engine mount. In any case, a crack is much more likely to occur at a weld, and be circumferential, than lengthwise.

A problem with the engine mount also will not be connected to a rise in ferrous metals in the oil analysis. You are chasing two different problems, unrelated, and one of which may not be a problem at all.
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  #3  
Old 03-01-2016, 10:13 PM
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MartinPred MartinPred is offline
 
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Location: Overseas
Posts: 158
Default Tiny Cracks

Greg,

In the picture, the cracks on the mount are the things that look like scratches. Very fine, but definitely cracks in the paint. Just not sure if the tube underneath is also cracked. Seems like a strange place for that to happen. I'll keep an eye on it.

As for the metal, Blackstone suggested that it might just be "the new normal" for my engine. And I'd hate to start tearing it apart if that's the case.

I'll probably fly another 20 hours or so, change the oil, and see how it looks.

-Matt
N402BD
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  #4  
Old 03-01-2016, 10:21 PM
Michael Burbidge Michael Burbidge is offline
 
Join Date: May 2006
Location: Sammamish, WA
Posts: 701
Default Mike Busch

Mike Busch wrote a very good article about how much metal is too much. That sort of thing. Look it up in the EAA archives.
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  #5  
Old 03-01-2016, 10:47 PM
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MartinPred MartinPred is offline
 
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Location: Overseas
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Default Great Tip

Of course. A quick google search reveals that Mike Busch has written a couple of articles on the subject. And Lycoming has issued some guidance in the form of Service Instruction 1492C.

Turns out in my case, since Aluminum is not elevated and the particles in the filter are few in number and smaller that 1/16", Both Mike and Lycoming recommend putting the plane back in service and checking again at the next regular oil change. So that's what I'll do.

Thanks guys!

-Matt
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  #6  
Old 03-02-2016, 06:00 AM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 6,518
Default

Your profile does not say where you are - like humidity and temperature environment. Looking at the time between changes, it appears the plane can sit a while. Depending how you fly - short vs long times, and how long the oil is hot, and if you use heaters it could be some mild corrosion due to internal moisture.

Silicon is not elevated, so it is not getting dusted.

If that is the case then changing your routine may help drop the iron. May not, but worth a try.

Do you have an oil separator or a straight exit breather?, is there any water related whiteness/condensate on the dipstick?

All these thing might give some clues, or it is a piston pin scraping the cylinder wall, or a slowly eroding cam/lifter unrelated to operation and nothing to do but open ad repair. In any case, more investigation is in order to prevent proper discovery of the root cause later on. No use in getting oil samples if no action is taken on the results. It may, indeed, be a fundamental issue unrelated to anything but chance.

PRL - what kind of barrels, and rings? Probably not ring de-lamination as oil consumption would be rising, so scratch that.

I really don't like iron in the filter after the initial oil changes cleans everything out. Good luck.
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Last edited by BillL : 05-14-2017 at 10:26 AM.
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  #7  
Old 03-03-2016, 10:36 AM
G5Driver G5Driver is offline
 
Join Date: Jul 2007
Location: Reno, Nevada
Posts: 22
Default

Matt,
No expert here, but if you think about the heat and friction inside of an internal combustion engine, it has to show some sign of wear or they would never wear out.
Remember, these are parts per million! With your current numbers and running condition it looks like you will make TBO with proper maintenance and oil changes no problem. JMHO.
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  #8  
Old 05-14-2017, 09:20 AM
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MartinPred MartinPred is offline
 
Join Date: Nov 2005
Location: Overseas
Posts: 158
Default Hard to Tell

Since last year I installed the magnetic drain plug and ran through a couple oil changes. At first I thought I was within the Lycoming limit of 20-40 hairlike ferrous particles of 1/16" or smaller. Now I'm starting to think I'm exceeding that limit. Here's what it looked like yesterday:




That stuff on the screen is non-ferrous carbon. No large ferrous particles. Oil filter had a very small amount of super-tiny ferrous particles. Still waiting for the sample analysis.

Time to pull jugs?

-Matt
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  #9  
Old 05-14-2017, 09:39 AM
David Paule David Paule is offline
 
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Location: Boulder, CO
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Regarding the engine mount, all I could see in the photo are the large lengthwise marks that appear, as airguy said last year, to be from something scraping it.

Typically, cracks in steel tube will be associated with and adjacent to the welds. They might also be circumferential or spiraling. I doubt there will be any lengthwise cracks unless the tube itself was manufactured poorly.

If you remove a bit of finish around a suspected crack, you might be able to tell with a 10x magnifying glass, called loups. A friend recently showed me a 40x one that included a tiny LED. Amazon sells inexpensive ones in that range. Better ones are Bausch & Lomb Hastings Triplet Magnifier, for a bit more money but still reasonable. For the visual inspection, 10x is sufficient.

A more rigorous test, also more expensive, would be something like dye penetrant test, and Aircraft Spruce sells those. You can do that with the engine mount in place.

Dave

Last edited by David Paule : 05-14-2017 at 09:41 AM.
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  #10  
Old 05-14-2017, 10:33 AM
BillL BillL is offline
 
Join Date: Sep 2007
Location: Central IL
Posts: 6,518
Default Fuzzy

That picture is hard to see. There are places that will analyze the particles and tell you what they came from, esp the ferrous ones. It could be a spalling lifter/cam, or a spalling gear. A better photo can tell if these are sheared pieces or spalled particles. They look like spalled generated.

Can you get a better focused and magnified photo of the particles? I have a little attachment for my iPhone that makes fantastic close up photos.

What ever it is, it is not going away.
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