Mystery metal in oil screen

[jaylw314]

33 minutes ago, EricJ said:

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.

MB tells the story of a couple ball bearings from a magneto going missing and presumed in the sump:

 

[HeyChuck]

On 7/21/2022 at 7:14 PM, takair said:

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

I don't know how cylinder plating peels off, but I think it would show up as wear metals in the oil analysis over time. These cylinders are Nickel carbide with over 1500 hours and no problems with the cylinder walls to date.

[HeyChuck]

On 7/22/2022 at 9:15 AM, 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. 

Oil consumption has been normal. I will send a sample of the metal to AvLab. Thanks!

[HeyChuck]

13 hours ago, skykrawler said:

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

The spin-on oil filter was clean. Removing the sump is difficult on these Continentals because of the engine mount. The borescope through the drain hold revealed most of the pieces in the picture, and I believe the IA removed what he saw. I don't know if the sump has ever been viewed this way before, so the pieces may have been in the sump a long time, and the one that was relatively skinny eventually got sucked through the pick-up tube to the suction oil screen.

[HeyChuck]

On 7/22/2022 at 7:07 AM, 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/

 

When you found the sheetmetal looking pieces from the rear engine bearing, were they in the oil screen, paper spin-on oil filter, or both?  If you were doing spectroscopic oil analysis, did you see any anomalous trends, such as high copper? Thanks!

[N201MKTurbo]

3 hours ago, HeyChuck said:

When you found the sheetmetal looking pieces from the rear engine bearing, were they in the oil screen, paper spin-on oil filter, or both?  If you were doing spectroscopic oil analysis, did you see any anomalous trends, such as high copper? Thanks!

Just in the suction screen. I was not doing oil analysis.

[carusoam]

Let’s see if @M20Doc is around…. (Metal pieces in the oil, no part numbers observed)

Best regards,

-a-

[Guest]

I’ve been following this with interest.  I’ve only seen something like this once before, but it was a chunk of main bearing backshell from a TSIO360 in a Piper Seneca.  The piece was about 0.100” thick.  We dropped the oil pan and found a main bearing had shifted and the bearing had broken.

.013” thick is really odd. Metallurgy hopefully can identify the material.

Clarence

[HeyChuck]

On 7/23/2022 at 7:50 PM, HeyChuck said:

Oil consumption has been normal. I will send a sample of the metal to AvLab. Thanks!

The lab analysis of this metal (quoted below) is consistent with possible delamination of one of the ECI Cerminil cylinders. Delamination problems on Nickel cylinders have apparently occurred, but may be rare. If that happened in this engine, it must have been near the cylinder base (crankcase side) where it couldn't be seen with the borescope. In another thread someone stated that engine shops are reluctant to hone Cerminil cylinders (for new piston rings)....perhaps it compromises the integrity of the nickel plating?

"THE 2 LARGE FLAKES THAT WERE SENT WERE DARK GRAY IN COLOR ON ONE SIDE AND A GREENISH-BROWN ON THE OTHER. THESE
PIECES COULD NOT BE MATCHED TO AN AMS NUMBER, CONSISTING OF NICKEL ON ONE SIDE AND LEAD ON THE OTHER. THIS MAY POSSIBLY BE
SOME SORT OF PLATING OR ANTI-WEAR COATING. THESE THIN FLAKES MEASURE APPROXIMATELY 1 X 0.75 INCHES AND 1 X 0.625 INCHES. THESE
FLAKES ARE FERROUS AND ARE VERY RIGID, BREAKING WHEN PRESSURE IS APPLIED INSTEAD OF BENDING. PLEASE CONTACT THE ENGINE
MANUFACTURER'S SERVICE REP IF FURTHER ASSISTANCE IS NEEDED."

[Guest]

It looks like cylinder removal is in you future.  Pulling one bank of cylinders should allow for inspection.

Clarence

[RLCarter]

2 weeks into the mystery metal and still no real answer, personally I wouldn’t have bothered with the metal analysis. No mater what or where it came from, it isn’t going to be good. An engine tear down and inspection will give you the answer. Even if it turns out to be top-end I would pull the oil sump and flush everything really good and honestly at that point I’d split the cases and do a field overhaul.

[HeyChuck]

6 hours ago, RLCarter said:

...No mater what or where it came from, it isn’t going to be good. An engine tear down and inspection will give you the answer. Even if it turns out to be top-end I would pull the oil sump and flush everything really good and honestly at that point I’d split the cases and do a field overhaul.

Possibly. It is also possible that a complete teardown will reveal no problem with the lower end. Although 1/10 teaspoon (total volume) of probable cylinder-plate metal was found in the sump, this engine has been very reliable, and currently has excellent cylinder compression, clean oil analysis indicating normal wear, relatively new starter, spark plugs, magnetos, alternator, etc. A Continental engineer thought the flakes likely came from the base of a cylinder during break-in, and advised not to pull any cylinders yet. They may also have worn during a cold, "dry" (minimal lubrication) start. Safety is paramount. Because engine failures are more likely to occur after major maintenance (top or major), careful diagnosis and targeted remediation is the conservative and safer approach than immediate tear down. A long ground-run with subsequent filter and sump inspections should come first. Perhaps removal of one cylinder will enable borescope inspection of the other cylinder's walls that couldn't be seen from above the pistons.

Regarding overhauls: Penn Yann and Western Skyways declined to quote because they cannot overhaul within the next year (think supply-chain issues) and/or parts availability and prices are too uncertain. Continental likely has best access to parts for overhaul; Continental quoted $87,258 and 7 months for a factory reman. The least expensive "field overhaul" I have been quoted is over $50K (about $60k with removal/installation, hoses, etc.) with a 6 month turn-around. Others are more expensive with turn around times on the order of 7-8 months, IF they can obtain parts.

[Browncbr1]

Given the cost and lead time of overhaul, I’d definitely pull some cylinders to see what can be found.  

[ArtVandelay]

I didn’t see where OP said the number of hours. If it’s close to TBO I would just overhaul it, when engines accumulate hours they can start having problems and be less reliable. Then you’ll be spending a few AMUs here and a few there.