The International Cessna^® 170 Association

I performed an annual on a 206 last year, cut the filter nothing out of the ordinary, but oil pressure lower than normal ( owner didnt catch this). Installed inline gauge to verify oil pressure, still lower that normal (just below green arc). Oil analysis indicated crank bearing material (smaller than 20 microns). Sent the engine to Western Skyways. Thru-bolt broke (they'd never seen this before), case crank journals moved away from crank, crank banging around in case.

Good catch. How low was the oil pressure reading?

When the oil was hot, just below bottom of the green arc. Engine had 600 hrs SMOH. As I mentioned, the owners never registered in their minds that the pressure was changing. A good example of why it is important to read the instruments and understand that they will tell us when things are changing. If it hadn't been due for annual, they would have flown till the case came apart.

So the first clue was lower-than-normal oil pressure indicator rather than oil analysis....and oil analysis confirmed your suspicions that the engine was in trouble? Good catch! (I think some folks would have tried to crank up the pressure by monkey-ing with the relief spring...a practice I have learned can simply mask deeper problems.)

Ditto

So once you get the element out of the can, what is the simplest, cleanest way of getting the paper portion away from the metal portion so you can lay it out flat and inspect it (like I've seen a couple mechanics do but I have missed the details).

I use a box-cutter to slice the paper circumferentially at the point where it meets the metal ends. Then, wash the paper in a container of solvent, catching the residue. (Plastic coffee "cans" work well.)
A magnet passed beneath the bottom will "move" ferrous particles without them clinging to the magnet. Pouring the laden solvent thru a coffee filter will allow the solvent to be re-cycled and catch the junk in the filter. Dark chips can be proved carbon by hitting them with a hammer on an anvil. (Metal will flatten/spread, but carbon will shatter.)

A box cutter will work but I use a hack saw blade which is a little longer. Use like a knife slicing the paper down to the core and running the blade down along side the metal end caps then around top and bottom. Pull the paper element out and do as George does which is very thorough or just examine the paper.

You will see black stuff at the creases specially. Don't be alarmed. You should be able to crunch it with your finger nail because its carbon. It's the stuff you can't crush your worried about.

Also you will find a sliver or two of metal in all likely Hood and this is normal. It's the quantity and size of metal as well at the type your paying attention to.

I've asked over the years how much metal is two much and of course have not gotten definitive answers. I recall but don't quote me, that as much at a 1/4 teaspoon is acceptable, but I know it would worry me.

Cheap box cutters with extendable (long) blades can be found at big box hardware stores. What are you doing up at this hour?

A old (or cheap) serrated steak knife is perfect for this job.

I keep getting a mental picture of a steel-filings-laden hacksaw blade being used to cut open a filter.... (Sorry, Bruce... I know... I just have this mentality.... )

George I clean the blade before I use it on the filter. Or maybe that is why 1/4 teaspoon of metal is allowed, I'm not sure.

The serrated kitchen knife would work as well but I don't have one of those in the hanger.

As for the time well it's not correct. (I've just corrected it in my profile) At that time of the writing I had just arrived at work.