Engine making a little metal...

[Michael Burbidge]

My engine has about 1100 hours SMOH.

I just finished an oil change. I found three small pieces of non-ferrous material in the sump screen. They were 1/32 inch in diameter or smaller.

My oil analysis came back with elevated aluminum (32 ppm) and elevated iron (255 ppm) Previously they had been at 5 ppm and 48 ppm respectively.

I did not find anything unusual in the oil filter. The filter contained about 1/32 teaspoon of ferrous material, and 1/32 teaspoon of non-ferrous material. No chunks. It was all dust-like size material.

My interpretation of the Lycoming guidance would be to check at next scheduled oil change. i.e. In 25 hours. That's my plan.

Some of you might remember, that a few months ago I installed a p-mag to replace one of my magnetos. You also might remember that I dropped a mag nut into the sump and had to fish it out with a boroscope and magnet. I'm wondering if all the stirring around I did in the sump might have stirred up some material that had been sitting in the bottom of the sump. It took quite a bit of fishing to retrieve the nut.

Also I had a question about the oil analysis. Do they prorate the ppm based on the number of hours? Because I noted on the form I sent to them that I had 25 hours on the oil, but I actually had 33. Not a big difference. But I was just curious. Would oil that had 50 hours on it have accumulated twice as much metal as oil that had 50 hours on it? i.e. would ppm be twice as high?

Thanks,
Michael-

[AltonD]

When you pull your oil sample, do you wait for a quart or so to flush the line before you pull the sample?

[Michael Burbidge]

Yes, I pull it after about 2 quarts.

Michael-

[DHeal]

You don't say what engine you have -- I'm guessing its a Lycoming 160/180? In my experience I would be thinking that you might have some excessive piston pin cap wear (usually numerous small fingernail-like aluminum slivers in the oil filter with some steel wear on the corresponding cylinder walls) or perhaps camlobes/lifters wear (usually small steel chunks in the filter without any extensive signs of aluminum wear). Then again, it could be something else or nothing at all.

[Michael Burbidge]

No finger nail like slivers. Just fine sand like particles. And like I said, very little of that. No where near the 1/4 teaspoon limit set forth in Lycoming Service Instruction 1492C.

Michael-

[BillL]

Are what they are. No prorating for the report. You can do that. IMO, it won't be getting any better.

Unless this is the first sample like this where you ran for a short time when it was cold and left it sitting for a couple of months (rusted cylinders), then again IMO, you have something going poorly.

Maybe piston/ring/cylinder, maybe grinding bearing, but large AND small particles would indicate (IMO) a progressing situation.

Borescope the combustion chamber should be a start, looks for scratching on walls, scoring at the PP location. Look at all cylinders.

Just my opinion. Been wrong before.

Edit: Maybe you can post the full analysis. Typically, the PPM rises in the oil for some period of time then breaks over as the filter is collecting more than it is passing. So the contamination levels sorta plateau. I say typical, as this is in a normal engine. As the filter collects more and more material the pressure drop increases and it may bypass on starting, or as oil pump pulses open the bypass. If the particle production increases, then the sump PPM will also plateau at a higher level. For large stationary engines, a sample valve is installed in the sending unit line. When it is hot, has been running, a purge sample is released, then a sample taken. Typically a 1/4" od line. You could do that and get a short hour sample w/o the filter and oil change. If so just make sure it is after the oil pressure restrictor, and use a metal cap for it as risk mitigation except for the flight prior to the sample extraction. Properly installed, you could use a hose relocated near the oil door so cowl removal is not needed. Just be sure to have an adequate purge. The purge oil can be returned to the sump later. Take appropriate precautions if doing this with the engine running. good luck.