[Snowflake]

Okay, how about this... Let's say your engine is shaving particles off large enough to see. As part of that particular wear/failure process, wouldn't we expect a *range* of sizes of particles to be removed, from detectable, micron-sized, all the way to visible? Not everything that gets shaved off will come off in visible-sized pieces. And if so, wouldn't the smaller pieces contribute to a change in the proportions of metals found in the oil sample?

 

[Toobuilder]

Oil analysis in engines serves to pre inform the operator of an impending failure. It can also inform the discrete component that is starting to fail. IE. An accessory gear, carbon seal, O- ring, etc. if it’s big enough to be caught in the filter, it’s WAY too late. Even the best filter is just a coarse garbage screen compared to what is studied for an oil burn analysis.

 

[DanH]

Let's say your engine is shaving particles off large enough to see. As part of that particular wear/failure process, wouldn't we expect a *range* of sizes of particles to be removed, from detectable, micron-sized, all the way to visible?

Yes.

And if so, wouldn't the smaller pieces contribute to a change in the proportions of metals found in the oil sample?

Yes. It should show any significant change for elements soluble in diluent, dissolved with acid, or delivered to the plasma as particles <10 µm, ballpark.

No one is sayin' ICP spectroscopy is without value. However, it has been built up in our community as an omnipotent "tell all". It's not so. In reality it has limitations, and they are useful to understand.

 

[planenutz]

No one is sayin' ICP spectroscopy is without value. However, it has been built up in our community as an omnipotent "tell all". It's not so. In reality it has limitations, and they are useful to understand.

100% Dan. Well said.

As I tell my customers - it is just one tool in the toolbox and it can assist in some circumstances, but its important to remember the other tools are also there to be used.

 

[planenutz]

Okay, how about this... Let's say your engine is shaving particles off large enough to see. As part of that particular wear/failure process, wouldn't we expect a *range* of sizes of particles to be removed, from detectable, micron-sized, all the way to visible? Not everything that gets shaved off will come off in visible-sized pieces. And if so, wouldn't the smaller pieces contribute to a change in the proportions of metals found in the oil sample?

As Dan said, yes... however let's consider for a minute that the metal in the filter is in the form of quite large flakes... say, 1/8th" diameter. The SOA results might show a slight elevation of iron and chrome, but how valuable is this information to you at this point? Not much help at all really because you are no longer trend monitoring, you are reacting. I would suggest it would be better to carry out an SEM analysis of the particles and determine exactly which material has been recovered, then use the metal map to determine where this material is employed within the engine.

 

[BillL]

Okay, how about this... Let's say your engine is shaving particles off large enough to see. As part of that particular wear/failure process, wouldn't we expect a *range* of sizes of particles to be removed, from detectable, micron-sized, all the way to visible? Not everything that gets shaved off will come off in visible-sized pieces. And if so, wouldn't the smaller pieces contribute to a change in the proportions of metals found in the oil sample?

Maybe. Let's say you had some corrosion on the cam followers- - immediately after that some of the particles likely went into the filter, and as it gets repolished, the SOA might show some increase in iron. Then the degradation continues. Now -the pieces spalled off will be larger, get entrained in the high speed vortex of the crank rotation, some fall on the cylinder walls, but most just get washed into the sump. As the hydrodynamic film has deteriorated (with a porous contact area), some wear (as opposed to spalling) will begin from metal-metal contact and generate (smaller) particles where some will not not sink to in the sump, but remain suspended/entrained in the oil flow- that gets into the filter. As spalling and wear continues, it is not likely (as pointed out) that the SOA alarm will go off.

It would be interesting to quantify the entire progression to failure of a slipper follower from the initial issue.

ChiefPilot - - You stated nicely- - " my engine might be clean inside and not generating debris "- - yep. My filter and SOA got cleaner with hrs and at 250 the SOA is pretty consistent - -I did fly out West a couple of years ago and 10-15 hrs in smoke tainted air. That pushed up my Fe in the SOA and took 2 more oil changes to get in line.

The air must be really clean in Minnesota!! Central Illinois is silica country so with spring and fall winds across corn/beanless fields it is noticeable.

SOA - oil filter inspection and finally suction screen inspection work together to address different failure modes.

DanH is doing a fantastic job of educating us on the details here. If it were charted it's beginning to look like an old oak tree, the leaves are the bits of knowledge.

 

[Snowflake]

As Dan said, yes... however let's consider for a minute that the metal in the filter is in the form of quite large flakes... say, 1/8th" diameter. The SOA results might show a slight elevation of iron and chrome, but how valuable is this information to you at this point? Not much help at all really because you are no longer trend monitoring, you are reacting. I would suggest it would be better to carry out an SEM analysis of the particles and determine exactly which material has been recovered, then use the metal map to determine where this material is employed within the engine.

Yes, I agree, if you're seeing 1/8" flakes in the filter, then you don't need an SOA to know you're in triage mode. But earlier I was getting the impression that people thought SOA wasn't valuable because it wouldn't report the larger particles. While it's true that larger particles won't be measured, there is a progression to consider. Before you get 1/8" particles, you'll get smaller particles, and if you're not to the 1/8" flakes point when you do your oil change, you should see elevated levels that make you wonder what's happening.

It would be interesting to quantify the entire progression to failure of a slipper follower from the initial issue.

I agree. I think that's what labs like Blackstone are trying to do, they do ask a lot of questions about operation conditions, and they do comment on levels that are off the "fleet average" numbers to suggest what could be causing them.

 

[newt]

But earlier I was getting the impression that people thought SOA wasn't valuable because it wouldn't report the larger particles.

I think it's not valuable because we don't do anything useful with the results.

If I cut my filter can open and inspect the pleats and it's full of iron filings, that'll ground the aircraft and see the engine booked in for intrusive maintenance.

If I do SOA and it comes back saying there's a slightly elevated ferrous metal count, I'll go, "Hrm," and keep flying. Next time I change the oil and cut the filter can open and inspect the pleats, I'll pay extra special attention to see if it's full of iron filings. Which I was going to do anyway because that's the normal thing you do even if you don't have a report of elevated ferrous metals, so the SOA result didn't help.

Heavy industry uses oil analysis to tell them what's failing so they can have the right spare parts available on hand next time the machine comes in for maintenance, minimizing revenue-affecting downtime. We don't operate our privately owned recreational vehicles like that.

Has anyone here ever learned anything from an oil analysis that's led directly to a maintenance outcome without evidence in the oil filter? If not, why do it?

- mark

 

[JonJay]

I think it's not valuable because we don't do anything useful with the results.

If I cut my filter can open and inspect the pleats and it's full of iron filings, that'll ground the aircraft and see the engine booked in for intrusive maintenance.

If I do SOA and it comes back saying there's a slightly elevated ferrous metal count, I'll go, "Hrm," and keep flying. Next time I change the oil and cut the filter can open and inspect the pleats, I'll pay extra special attention to see if it's full of iron filings. Which I was going to do anyway because that's the normal thing you do even if you don't have a report of elevated ferrous metals, so the SOA result didn't help.

Heavy industry uses oil analysis to tell them what's failing so they can have the right spare parts available on hand next time the machine comes in for maintenance, minimizing revenue-affecting downtime. We don't operate our privately owned recreational vehicles like that.

Has anyone here ever learned anything from an oil analysis that's led directly to a maintenance outcome without evidence in the oil filter? If not, why do it?

- mark

Way more folks post here about chasing ghosts than discovering an actionable item due to oil analysis findings.

 

[ChiefPilot]

I finally got my results back from Blackstone; they took several weeks longer than LabOne to return the results but the analysis is also more detailed, so there's that. Anyway, the analysis was done after running the oil on an advertised 22um Champion screen. Time in service was just a hair over 49 hours since the previous oil change on an Aerosport IO-360-B1B with not quite 1400 hours on it since new.



Since this was the first time I'd submitted a sample to Blackstone, they had no history on this engine, but their results are very close to those of LabOne which shows nothing concerning as far as trend of materials etc. All happy there. Cleaning the filter, there were some discretely identifiable particles left in the cleaning solution along with a dark gray "dust". None of it magnetic, and only an occasional sparkly particle so I assume it to be mostly carbon or non-wear material.

What I was really interested in here was the insolubles and particle counts (particle count was an extra cost). I expected to see more in the 38µm and 70µm ranges given statements that the Challenger filters catch nothing 10 µm to around 100 µm range; that's not the case obviously and seems inconsistent with the reported oil filter test from that thread. Similarly, the insoluble percentage was lower than I expected, with the lab comment of "Low insolubles show the filter wasn't used up when you took this sample."

I'm running a Wix filter on the engine now and will get another particle count analysis done to compare the two after the next oil change.

 

[DanH]

What I was really interested in here was the insolubles and particle counts (particle count was an extra cost). I expected to see more in the 38µm and 70µm ranges given statements that the Challenger filters catch nothing 10 µm to around 100 µm range; that's not the case obviously and seems inconsistent with the reported oil filter test from that thread.

Think about it again.

If the 38 and 70 µm particles were not present in the engine, they don't appear in the oil. That's the very large difference between a Blackstone report and the ISO standard...the ISO standard doses the oil with all particle sizes, and counts them both in and out of the filter

Your conclusion is similar to saying "Someone cleaned out my bank account", when no one had ever made a deposit.

 

[ChiefPilot]

Think about it again.

If the 38 and 70 µm particles were not present in the engine, they don't appear in the oil. That's the very large difference between a Blackstone report and the ISO standard...the ISO standard doses the oil with all particle sizes, and counts them both in and out of the filter

Your conclusion is similar to saying "Someone cleaned out my bank account", when no one had ever made a deposit.

So you are suggesting that there are not, in fact, particles of the range in question present in the engine yet particles both smaller (from the particle count data) and larger (from visible inspection) exist? That seems a stretch, but I could be wrong.

 

[Freemasm]

So you are suggesting that there are not, in fact, particles of the range in question present in the engine yet particles both smaller (from the particle count data) and larger (from visible inspection) exist? That seems a stretch, but I could be wrong.

You would expect a geometric relationship for particle size vs count. This is exactly what your data is telling you. Anything else would be highly suspect or indication of a problem. I'd be quite happy if I were you.

 

[ChiefPilot]

You would expect a geometric relationship for particle size vs count. This is exactly what your data is telling you. Anything else would be highly suspect or indication of a problem. I'd be quite happy if I were you.

If not only the oil analysis but also the particle counts are something I should be quite happy with, I'm failing to understand why I should want to change anything about the setup - including the screen filter that was used during that period. There's always "better", of course, and I'm not arguing that the screen filters are better than the Wix unit currently installed. But based on your logic, the screen filters are "good enough" as I should be happy with those results.

 

[Freemasm]

If not only the oil analysis but also the particle counts are something I should be quite happy with, I'm failing to understand why I should want to change anything about the setup - including the screen filter that was used during that period. There's always "better", of course, and I'm not arguing that the screen filters are better than the Wix unit currently installed. But based on your logic, the screen filters are "good enough" as I should be happy with those results.

The particulate distribution is exactly as you'd expect and your elementals were very good. This analysis is a snapshot in time suggesting nothing is currently happening within your PP that would be cause for concern. It in no way is predicting future results/consequences. Again, I'd be quite happy (in this moment) if I were you.

That said, this analysis can't be used to say that the related wear/Service life wouldn't be improved through improved oil conditions. That study would take a long time and include a lot more variables.

No more. No less

 

[ChiefPilot]

The particulate distribution is exactly as you'd expect and your elementals were very good. This analysis is a snapshot in time suggesting nothing is currently happening within your PP that would be cause for concern. It in no way is predicting future results/consequences. Again, I'd be quite happy (in this moment) if I were you.

That said, this analysis can't be used to say that the related wear/Service life wouldn't be improved through improved oil conditions. That study would take a long time and include a lot more variables.

No more. No less

They weren't exactly as I'd expect - they were quite a bit better than I'd expect if the screen filter did nothing as has been claimed. Otherwise, I totally agree that this analysis represents a snapshot in time and not predictive of the future.

 

[RV8JD]

I finally got my results back from Blackstone; they took several weeks longer than LabOne to return the results but the analysis is also more detailed, so there's that. Anyway, the analysis was done after running the oil on an advertised 22um Champion screen. Time in service was just a hair over 49 hours since the previous oil change on an Aerosport IO-360-B1B with not quite 1400 hours on it since new.

View attachment 65151

Since this was the first time I'd submitted a sample to Blackstone, they had no history on this engine, but their results are very close to those of LabOne which shows nothing concerning as far as trend of materials etc. All happy there. Cleaning the filter, there were some discretely identifiable particles left in the cleaning solution along with a dark gray "dust". None of it magnetic, and only an occasional sparkly particle so I assume it to be mostly carbon or non-wear material.

What I was really interested in here was the insolubles and particle counts (particle count was an extra cost). I expected to see more in the 38µm and 70µm ranges given statements that the Challenger filters catch nothing 10 µm to around 100 µm range; that's not the case obviously and seems inconsistent with the reported oil filter test from that thread. Similarly, the insoluble percentage was lower than I expected, with the lab comment of "Low insolubles show the filter wasn't used up when you took this sample."

I'm running a Wix filter on the engine now and will get another particle count analysis done to compare the two after the next oil change.

Brad, Thanks for posting.

Off topic a little: What oil (and additives, if any) are you using? Did Blackstone comment on the two measured Viscosity numbers? They seem a bit low compared to the numbers Blackstone always measured for my oil samples, and compared to the normal range they state for those measurements. Just curious is all.
My last several samples:

 

[ChiefPilot]

Brad, Thanks for posting.

Off topic a little: What oil (and additives, if any) are you using? Did Blackstone comment on the two measured Viscosity numbers? They seem a bit low compared to the numbers Blackstone always measured for my oil samples, and compared to the normal range they state for those measurements. Just curious is all.

I thought that interesting as well. Will call and try to learn more about that once I finish a trip. They said it was about 80W in the commentary. I use no additives and it was just Phillips XC20W50 oil for the whole 49hrs.