Mystery metal in oil screen

[HeyChuck]

Found a large piece of thin (.013"), brittle, ferrous metal in the oil suction screen of my TSIO-360SB during the annual inspection today. Further investigation found several larger pieces in the oil sump (picture attached, penny for scale). There is a gentle curve on at least one of them. These are likely too thin and wide to have come from an impulse coupling or push rod spring. We are wondering what might be coming apart (it wasn't the oil dipstick) ... any ideas?

[takair]

Hard to tell how thin in the picture….can it be plating?  Do you have chrome cylinders? 

[StevenL757]

2 hours ago, HeyChuck said:

Found a large piece of thin (.013"), brittle, ferrous metal in the oil suction screen of my TSIO-360SB during the annual inspection today. Further investigation found several larger pieces in the oil sump (picture attached, penny for scale). There is a gentle curve on at least one of them. These are likely too thin and wide to have come from an impulse coupling or push rod spring. We are wondering what might be coming apart (it wasn't the oil dipstick) ... any ideas?

 

If you run your engine ROP, it produces pennies.

If you run it LOP...it starts producing quarters or better.  

Seriously, I hope this is nothing serious and that you get it sorted quickly and as inexpensively as possible.

Steve

[HeyChuck]

Thanks for the follow-up question. The nickel carbide cylinders on this engine have been reliable (1530 hours to date); but had to replace two burned exhaust valves a couple years ago. The spin-on filter element was clean...still waiting for the oil analysis.

[N201MKTurbo]

On my engine, which is a Lycoming, I found Sheetmetal looking pieces. They turned out to be the outer cladding of the rear engine bearing. It turned out to be a cracked bearing saddle. I repaired it myself so it only cost $20K. My pieces were smaller than that. I can't see how pieces that big could get out in one piece. If the diameter of the curvature is about 2 1/2 inches that would be consistent with a main bearing.

https://www.enginelabs.com/engine-tech/engine/the-simplicity-and-sophistication-of-engine-bearings-part-1/

 

Edited July 22, 2022 by N201MKTurbo

[Shadrach]

1 hour ago, N201MKTurbo said:

On my engine, which is a Lycoming, I found Sheetmetal looking pieces. They turned out to be the outer cladding of the rear engine bearing. It turned out to be a cracked bearing saddle. I repaired it myself so it only cost $20K. My pieces were smaller than that. I can't see how pieces that big could get out in one piece. If the diameter of the curvature is about 2 1/2 inches that would be consistent with a main bearing.

https://www.enginelabs.com/engine-tech/engine/the-simplicity-and-sophistication-of-engine-bearings-part-1/

 

I had the same thought when I saw the original picture but it seemed implausible that bearing material in such a state could make it into the suction screen without additional and very noticeable symptoms.

[N201MKTurbo]

12 minutes ago, Shadrach said:

I had the same thought when I saw the original picture but it seemed implausible that bearing material in such a state could make it into the suction screen without additional and very noticeable symptoms.

My engine was running perfectly when I found the flakes. I had just finished a 6 hour cross country the day before the inspection.

[N201MKTurbo]

I hate to say it, but it is probably going to take an engine teardown to find the source of that metal. You may be able to fix it and re-assemble it if it is a low time engine. 

[takair]

2 hours ago, HeyChuck said:

Thanks for the follow-up question. The nickel carbide cylinders on this engine have been reliable (1530 hours to date); but had to replace two burned exhaust valves a couple years ago. The spin-on filter element was clean...still waiting for the oil analysis.

I’m leaning toward cylinder plating flaking. Has your oil consumption gone up at all?  Could be from the bottom of the jug where it may not contribute to that but also hard to find on borescope. I think you can send the metal to one of the labs and they can help narrow down the source. If a jug, you might just need to pull one at a time. 

[dzeleski]

Is it flexible or brittle? It does appear to look like a coating failure of some kind. Yank the top plugs and spin the engine so each cylinder gets to the bottom of its stroke and get a borescope in there.

This is not an aviation plating company but the info is still applicable.

https://www.millennium-tech.net/plating.php

 

Why do coatings peel, and is that normal?

Peeling coatings can be caused by many factors. When the coating is applied properly the nickel will bond stronger to the aluminum than the aluminum bonds to itself or about 25,000 psi. In other words, the coating has higher tensil strength than the aluminum does. Because of this bond, when seizure occurs and plating comes off, there is often aluminum that comes off with it. Coatings will most often peel as a result of substandard materials being used, or when a processing error occurs.

 

Is the coating sprayed on, and how thick can it be put on?

No. The coating is an electroplated process that uses an electrical current to adhere the nickel and silicon carbide molecules to the aluminum. The process does involve dipping the entire part into the plating solution, and an electrical current must be present to start the plating process. Coating thickness varies with each cylinder and is determined by the amount of time it is in the tank as well as the amount of power used. The industry standard of plating thickness is between .003" to .005" with a useful limit of .040" thick. Applying the coating more than .040" is possible, however the coating becomes erratic if over this thickness. Another side effect is that the internal stress in the coating may cause it to crack when exceeding .040" thick.

[Shadrach]

35 minutes ago, takair said:

I’m leaning toward cylinder plating flaking. Has your oil consumption gone up at all?  Could be from the bottom of the jug where it may not contribute to that but also hard to find on borescope. I think you can send the metal to one of the labs and they can help narrow down the source. If a jug, you might just need to pull one at a time. 

Is it possible to see the backside of the pistons/cylinders via borescope? Perhaps through dipstick port with the tube removed?

[N201MKTurbo]

1 hour ago, takair said:

I’m leaning toward cylinder plating flaking. Has your oil consumption gone up at all?  Could be from the bottom of the jug where it may not contribute to that but also hard to find on borescope. I think you can send the metal to one of the labs and they can help narrow down the source. If a jug, you might just need to pull one at a time. 

It seems like you could see that with a borescope.

[GeeBee]

Before you tear down or tear in maybe you should send the material to AvLabs to see if they can identify the origins. The often can do so by the alloy or make up of the material. I had mystery metal in an O-320 they identified immediately.

https://www.avlab.com

 

[tgardnerh]

IIRC there are options to send chunks like that for analysis--the lab can tell you the alloy, and then you can cross reference against the parts list for your engine and narrow down the source.
Seems like an appealing option before removing and tearing into the engine to diagnose.


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[HeyChuck]

I contacted AvLab to arrange a metallurgical analysis which might discern if the alloy is used in cylinder plating vs. bearing cladding. However, now that the IA has seen the metal in the sump, he points out that regardless of the metal provenance, the unknown quantity of additional metal that may be present somewhere in the engine could obstruct the engine oil pump. Although bore scope inspection of the sump does not show more metal, it could be "hiding" somewhere...and the airplane is not safe to fly without an engine teardown...I am afraid I will likely be shopping for a major overhaul next week.

[Marauder]

I contacted AvLab to arrange a metallurgical analysis which might discern if the alloy is used in cylinder plating vs. bearing cladding. However, now that the IA has seen the metal in the sump, he points out that regardless of the metal provenance, the unknown quantity of additional metal that may be present somewhere in the engine could obstruct the engine oil pump. Although bore scope inspection of the sump does not show more metal, it could be "hiding" somewhere...and the airplane is not safe to fly without an engine teardown...I am afraid I will likely be shopping for a major overhaul next week.

Holy crap man. I just saw this thread. What you are going through is my worst fear. I changed my oil this afternoon and found this on the magnet after running the magnet through every pleat in the filter. Finding anything bothered me. I don’t know if I could handle what you found! Good luck.




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[ArtVandelay]

IIRC there are options to send chunks like that for analysis--the lab can tell you the alloy, and then you can cross reference against the parts list for your engine and narrow down the source.
Seems like an appealing option before removing and tearing into the engine to diagnose.


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Doesn’t matter the source, when you have penny sized metal, it’s time for an overhaul.

[takair]

10 hours ago, HeyChuck said:

I contacted AvLab to arrange a metallurgical analysis which might discern if the alloy is used in cylinder plating vs. bearing cladding. However, now that the IA has seen the metal in the sump, he points out that regardless of the metal provenance, the unknown quantity of additional metal that may be present somewhere in the engine could obstruct the engine oil pump. Although bore scope inspection of the sump does not show more metal, it could be "hiding" somewhere...and the airplane is not safe to fly without an engine teardown...I am afraid I will likely be shopping for a major overhaul next week.

Consider this. If you could identify the metal as cylinder plating, and if you could then verify which cylinder….pull that cylinder to do further analysis. The metal is large enough that they are like puzzle pieces. If you can account for all of the missing plating this way, perhaps you don’t need a full tear down, just a new jug. If all of the metal is not accounted for, make a decision from there. The risk is being out the cost of pulling the jug. 

[skykrawler]

Of course you've removed and cut the oil filter by now.   You could remove the sump and see if there is more debris.

[Ragsf15e]

The OP doesn’t have chrome cylinders, but just as an example, I do and they had to be replaced because they eventually lost the plating.  We were able to watch this happen through a borescope over several annuals and 3 years.  Never saw anything in the screen or filter.  My oil analysis has always come back with slightly higher chrome levels than the io-360 standard.  I attribute this to the plating coming off in very, very small bits.  I got the chrome cylinders overhauled and still have the same slightly high chrome level but nothing in the filter/screen.

[EricJ]

Has the sump ever been checked before?   If not, that stuff might have been in there a long time and dropped in either though the oil fill tube or through an accessory pad during maintenance.   I'm told it's semi-normal to find magneto couplers in the sump after somebody dropped one in and replaced it rather than fish it out.

The metallurgical analysis should be useful.

[aviatoreb]

Full disclosure - I don't know what I am talking about - but I would worry that no matter the source, once metal pieces that size are floating around in the system, that they would get churned up by all sorts of other moving parts in the system, then scratch, grind and ruin everything in its path.  And as those bigger pieces get ground to smaller pieces, they would find their way into more and more secondary places.  So even if it started as plating in the cylinders, how long would it be before you have pieces of metal in the lowers ruining everything down there?

[Danb]

16 hours ago, Marauder said:

Holy crap man. I just saw this thread. What you are going through is my worst fear. I changed my oil this afternoon and found this on the magnet after running the magnet through every pleat in the filter. Finding anything bothered me. I don’t know if I could handle what you found! Good luck.




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I can only assume you changed your oil yesterday your thinking there’s a chance your supply would be missing

[Marauder]

I can only assume you changed your oil yesterday your thinking there’s a chance your supply would be missing

You betcha. I was watching you case the joint as I was filling your oxygen up.


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[EricJ]

4 hours ago, aviatoreb said:

Full disclosure - I don't know what I am talking about - but I would worry that no matter the source, once metal pieces that size are floating around in the system, that they would get churned up by all sorts of other moving parts in the system, then scratch, grind and ruin everything in its path.  And as those bigger pieces get ground to smaller pieces, they would find their way into more and more secondary places.  So even if it started as plating in the cylinders, how long would it be before you have pieces of metal in the lowers ruining everything down there?

It's not unusual in all kinds of motors to find stuff that's just sitting in the bottom of the sump once it gets opened up for a rebuild or the pan is dropped.   There's often no way to know how long something has been in there.   Parts, tools, pieces, mystery material, etc.  The suction screen is there to keep that stuff from getting into the pump and damaging the pump gears.   If it is too big or doesn't make it into the suction screen it will likely just sit in the sump.

Most motors have a physical separation between the sump area and the crank windage, either a windage tray or something similar or, in the case of the four-cylinder lycomings, the crankcase halves extend down around the crank and separate the two with just drainage slits allowing oil back into the sump.   In most motors once something large-ish makes it way into the sump it just sits there.   I'm not familiar with how that particular Continental motor is configured, but I'd be surprised if there isn't a separation of some kind.