You know you're having a bad day when......

[Anticept]

Oil analysis, or also called SOAP, is used to track the decay of the engine by watching the trends of materials found in the oil. As an engine wears, it will deposit more and more particles into the oil suspension. If a part in the engine starts to break down, you will see a spike in the materials used to make that part.

 

It is used to phenominal efficiency in the airlines. With all the sensor data and soaps, they can pin down the day of failure weeks in advance!

 

In recips, it's hit and miss though. Soaps can tell when a part is breaking down, but it doesn't detect fatigue.

[Roger Lee]

Hi Jim,

 

$402 per set of two. You must replace the exhaust and intake on each cyl. at the same time.

 

 

Hi Anticept,

 

Exactly.

 

But each owner must make up their own mind.

[FredG]

Oil analysis, again. It makes the mechanic feel good. As Doug G. said, no one has provided a clear statement of how the results of oil analysis are used to alter or modify engine operations or maintenance practices.

 

Simply calling it a "tool in the toolbox" sounds good, but it doesn't mean anything. A tool that leads to what result? I asked last time this came up. What did anyone do differently as a result of an oil analysis? What does Rotax recommend we do with the results of oil analysis?

[Jim]

So four sets at $402 each, $1608 plus labor. I'd rather have a discount on these than a discount on a destroyed engine...

[Roger Lee]

Labor is easy. I could replace a set in about 15 min. each and when done torquing and aligning in another 20 min. So about 1.5 hrs. 2 hrs if your slow. The lifters are easy to access.

[Roger Lee]

I think I'll keep doing mine and my customers. No one is going to make everyone use an oil analysis, but if you haven't ever talked to 1-2 labs or read many articles done some research or talked to anyone that it was useful to then you may feel it isn't worth the effort.

Oil analysis is a proven tool when fully understood (this may be the issue), it's used to show trends and can show part failures in the making and oil issues.

 

It's a personal choice just like determining when to change a tire on your car. At what point does each person make that decision and who makes good ones verses bad ones.

 

http://esource.alstribology.com/WB022_Jul_09/Aviation_Article_Klippel.html

 

http://www.avweb.com/news/maint/185087-1.html?redirected=1

 

http://www.myrv10.com/tips/maintenance/ShellCareAero_878_95.pdf

 

http://www.oilanalysisuk.com/theimportanceofoilanalysis.html

 

http://www.aviationpros.com/article/10387222/oil-analysis-an-essential-part-of-engine-monitoring-programs

 

http://www.wseas.us/e-library/transactions/information/2009/29-741.pdf

 

http://grounds-mag.com/mag/grounds_maintenance_benefits_oil_analysis/

 

http://www.piperowner.org/articles/55-featured-article/414-the-benefits-of-oil-analysis-regular-testing-keeps-your-engine-healthy-and-happy.html

 

http://www.machinerylubrication.com/Read/29004/oil-analysis-benefits

 

http://www.swaviator.com/html/issueja02/Hangar7802.html

[FlyingMonkey]

So Roger, would the lifters be a one-time replacement on 2006-2007 engines, or would that be something that could save some heartache by being done every 500 hours or so? So figure $1600-1700 plus a couple hours labor? I would not really be planning on doing this, it's a little steep (for my wallet) for preventive maintenance on top of annuals, 100hr Rotax inspections, etc...just curious.

[Roger Lee]

I don't see a reason to do it at all.

Most lifters last the life of the engine. It has been a very rare few that have had an issue. For 2006-2007 we are talking in the neighborhood of 8+K engines. It's still rare. We all take pills and they all have side affects and many times even death is listed, but we take them anyway. Of course few ever read all the side affects. So we are all gambling in some way, shape or form.

[FlyingMonkey]

I don't see a reason to do it at all.

Most lifters last the life of the engine. It has been a very rare few that have had an issue. For 2006-2007 we are talking in the neighborhood of 8+K engines. It's still rare. We all take pills and they all have side affects and many times even death is listed, but we take them anyway. Of course few ever read all the side affects. So we are all gambling in some way, shape or form.

 

What metals would the oil analysis show if the lifters start breaking down? If they are hardened I'm guessing Iron?

[Anticept]

What metals would the oil analysis show if the lifters start breaking down? If they are hardened I'm guessing Iron?

 

It depends on where the wear is occurring. You will definitely find carbon steel in it though, unless it's wearing in a place that is not the journal or bearing (that would make me wtf?).

 

There are SO MANY metals that go into engines. We don't use 100% pure metals in anything (with the rare rare exception) because pure metal of any type is extremely soft. We use all kinds of alloying agents to make them strong. Aluminum tends to be mixed with trace amounts of copper, iron with carbon, and magnesium with aluminum and manganese.

 

That's why soaps go to labs. They have the metallurgical experience.

 

Oil analysis, again. It makes the mechanic feel good. As Doug G. said, no one has provided a clear statement of how the results of oil analysis are used to alter or modify engine operations or maintenance practices.

 

How SOAPs translates to savings: it doesn't. That's not the purpose. The purpose of SOAPs is to try to find engine problems early before they occur in flight.

 

Soaps ARE good to use if you plan on flying until the engine shows problems, instead of following TBO. That's where SOAPs shine, and that's why airliners use SOAPs instead of TBOs. But there's a problem: I said "plan to". SOAPs measure trends. SOAPs are not magical that you can just start doing when you suspect engine problems, because there won't be a trend to compare. Also, turbine engines can have pretty severe failures and keep on running. Recip engines have a much lower tolerance. So that window to catch a problem with a recip using SOAPs is much smaller.

[Doug G.]

How many ppm does it take to tear down an engine? How far does a trend go before you take maintenance action?

The airlines work on turbine engines and more than likely have solid numbers to work with especially in reference to bearings. We don't have such a thing.

You speak of trends. In the report you posted above copper is at 10ppm. If the next one comes back high, there is a trend, do you year down the engine then to do “ exploratory surgery" or do you look for copper in the filter, or some other indication of a problem?

I am not trying to argue with you Roger, I am trying to figure out some actual, practical, difference oil analysis will make in my maintenance procedures and how to implement them. The fact that it is "only $20 a year" doesn't cut it. If there is no practical way to use the numbers, no standards to follow, no actual change in what maintenance is done - I'd rather give the $20 to one of my grandchildren.

[Roger Lee]

The numbers are on the report for out of spec. Look at the report posted. These numbers are adjusted for the engine time. That's why it's important to pick a company with a large data base. One number out of spec doesn't alarm me especially if it is barely over. It is a watch, but several numbers out of spec and or off the charts is a major alarm.

[Anticept]

How many ppm does it take to tear down an engine? How far does a trend go before you take maintenance action?

The airlines work on turbine engines and more than likely have solid numbers to work with especially in reference to bearings. We don't have such a thing.

You speak of trends. In the report you posted above copper is at 10ppm. If the next one comes back high, there is a trend, do you year down the engine then to do “ exploratory surgery" or do you look for copper in the filter, or some other indication of a problem?

 

Doug,

 

You're looking at this wrong. SOAPs are something that you do so you have data to work with. There's only guidelines of what is acceptable tolerance. Some engines are below guideline, some are above. Yet both can be perfectly fine. This is why we trend the engine. If you are seeing (these are just numbers being pulled out of my ass) 10ppm of metals in the oil on your first SOAP at annual, 11 ppm on your second soap at annual, 13 ppm on your third annual, 15 ppm on your fourth annual, then 75 ppm on your fifth annual, right then it might be time to do engine work. Or maybe it won't, especially if you had to do work on the engine. A slow climb of metals in the oil is normal, but when it spikes, that's when you have to think about taking action, because that's when something is abnormal.

 

SOAPs also hint at what is breaking down. Different parts have different alloys. They can tell you if they suspect it's a gearbox problem, a camshaft problem, bearing problem, or an oil pump problem. SOAPs can even hint if you've been running contaminated gas, or if you need to be doing more frequent oil changes!

 

Again, I'm trying to tell you, what you are trying to ask is us to provide a manual on forensics. SOAPs are an art. You could even say SOAPs are like an insurance policy. You might need it, you might not.

 

Finally, when you do a SOAP, you must track in detail everything you are doing to the engine. How much oil you've put in and when, any work you've done on it, what kind of gas you are running, etc. The more detailed that this information is, the more useful the SOAP data will be.

[FredG]

Roger, the numerous web links you provided do not anwer any of the questions that are being asked. Some are from sites that sell oil analysis, not exactly an objective source.

 

We have never heard of a single example of an engine being taken out of service when all observations are good (e.g., mag plug, oil filter inspection, etc) but the oil analysis is bad (or "trending"). We do not even have an example of any changes in operation or maintenance under such circumstances. We have no guidance from Rotax about acceptable and unacceptable oil analysis parameters.

 

Nor have we ever heard of a single example of an engine being kept in serivce when any definitive parameter is bad (e.g., mag plug contamination, oil filter inspection, etc) and oil analysis is good.

 

So, it appears to add no informaiton on which any action is taken. Every field, even technical ones, have their own mythologies. So far, this seems like an example.

 

Oh yeah, has anyone split samples (same oil, two samples to same lab or samples to two different labs)? Does anyone know if the oil analysis is reproducible (a necessary characteristic for validity)?

[Anticept]

FredG: that's because again, it's an art. Both me and roger are trying to tell everyone here, SOAPs are NOT A DEFINITIVE ANSWER. They are an additional data source. They will ONLY be as useful as the person who INTERPRETS them. The airlines use it to great efficiency, and is one of the best tools that they have. But guess what? They have an entire department who's job is to sit there and look at data all day long, and coordinate engine maintenance. And as I said, SOAP is an additional data plot.

 

It's like asking if it's necessary to have a CHT and EGT on every cylinder. In theory, yes, you can trend each individual cylinder. But it's stupidly expensive to install and maintain that. If you don't think that you need to do a SOAP, then don't. Roger and I are just sharing our opinions on them.

 

As for asking about taking an engine out of service based on a bad SOAP: for one, we're talking about Rotax engines. Rotax is an extremely conservative manufacturer, and you probably won't see a bad SOAP before TBO. It's not until you start running after TBO that SOAPs become extremely useful. If I were running after TBO, and the SOAP starts showing some elevated trends, I'd start an overhaul. If it's a 500 hour engine and we're seeing indications of a crankshaft break down, but it's only a little elevated, I'll just have another SOAP done soon after a few more hours of operation (remember that I said you need to track your oil? If you are meticulous, they can adjust their readings to account for a SOAP timetable change!) and see if it's still rising quickly. If it is, I'm having the engine torn down. If it's stabilized, I'll resume normal ops. Why? Sometimes how you extract the oil could have an effect. Maybe I didn't run the engine long enough before draining the oil. Maybe I didn't get to draining it quickly enough and some of it settled in the tank, and it didn't flush out until next change.

 

It also happens that an engine requires an overhaul even though the SOAP shows normal. Even though it's trending slowly, if you have a 4,000 hour engine, it can still be worn out. SOAPs are designed to detect rapid changes in trend, they are not designed to tell you when your engine is worn out, or if the engine is fatigued.

 

Seriously. This is turning into another version of "stall landing or flying it on" debate, there's valid points to both camps .

 

As for verifying oil samples: some labs test the samples multiple times. If you want second opinions, then feel free to send samples to multiple labs. Keep in mind though, SOAPs include the oil filter, so you can't exactly send multiple oil filter samples or you will break the trending.

 

Now, if anyone is asking about SOAPs being required for Rotax to step up like they did with the engine that started this thread, I honestly don't know. The thing is, Rotax doesn't have to do that. Sometimes they are picky, sometimes they aren't. The whole SOAP recommendation thing is probably another "because the lawyers said so" statement. I will say this though: if you sit there thinking "Well if I do these SOAPs and something goes wrong with my engine, Rotax will replace it!", then get out. You're doing it for the wrong reason and will be just another crybaby if Rotax goes "Sorry about your luck!"

[FredG]

"Roger and I are just sharing our opinions on them". Yes, and I am just sharing mine. BTW, I dont do oil analysis because, as noted, I dont see how it affects any decision.

 

Regarding data and "art", I am familiar with the interpretation of data and I prefer to use an evidence-based approach.

 

Just so I am clear, you wrote, "If it's a 500 hour engine and we're seeing indications of a crankshaft break down, but it's only a little elevated, I'll just have another SOAP done soon after a few more hours of operation (remember that I said you need to track your oil? If you are meticulous, they can adjust their readings to account for a SOAP timetable change!) and see if it's still rising quickly. If it is, I'm having the engine torn down." So, you would open an engine with normal compression, a clean mag plug, and a clean filter that was running fine, on the basis of two consecutive oil analyses showing "crankshaft breakdown"? Just asking.

 

Regarding Rotax and engines that are out of warranty, that was never my interest in this topic.

[Anticept]

Just so I am clear, you wrote, "If it's a 500 hour engine and we're seeing indications of a crankshaft break down, but it's only a little elevated, I'll just have another SOAP done soon after a few more hours of operation (remember that I said you need to track your oil? If you are meticulous, they can adjust their readings to account for a SOAP timetable change!) and see if it's still rising quickly. If it is, I'm having the engine torn down." So, you would open an engine with normal compression, a clean mag plug, and a clean filter that was running fine, on the basis of two consecutive oil analyses showing "crankshaft breakdown"? Just asking.

 

It's clean now, sure. But when parts start to break down abnormally, they will usually show up in oil analysis first. Also, we didn't say anything about filters . Filters are part of SOAPs anyways. Finally, I said if it spiked, but stabilized, I would not tear down. BUT, If it's rising rapidly on one SOAP, and still rising rapidly on the second, you bet your backside I'm going to have it checked! I didn't say overhauled on this 500 hr engine, just a teardown. I said overhauled on a past TBO engine.

 

Also, by the time you see metals on the mag plug, they will have also been running through other engine parts. Mag plugs are an after-the-fact check. Once you've got a dirty mag plug, the damage is done to other parts.

 

Also, to illustrate a point that it can be hard to detect problems, even though it all seems normal, is as follows. You should know that one reason that you shouldn't run an engine at takeoff power before warming it up, is that the main bearings will have difficulty getting proper lubrication (at least in Continentals and Lycomings). One of my A&P instructors had NUMEROUS engines come in where the bearing near the prop was wallowed out, as the crank was wearing against it, a sign of taking off with cold oil. As the bearing space enlarges, the wear increases. It all SEEMS normal, but this definitely is not a normal operating condition!

[Doug G.]

I assume that the A&P in that situation would find metal in the filter, or a leak at the seal.

Since this is an art and has nothing to do with actually analyzing thing in a scientific, quantifiable way; and because I only work on one engine; and because Rotax only recommends it and gives no supporting reason or data to be followed, and because the most experienced person I know on Rotax engines of all types - Bryan Carpenter - says it has no value... the braids will get my money.

[FredG]

Anticept, I agree, we are no longer making progress.

[Anticept]

I assume that the A&P in that situation would find metal in the filter, or a leak at the seal.

 

The oil analysis would find it sooner. It's a type of fretting corrosion, called false brinelling. This is something that is occurring over a significant amount of time, but accelerates as the damage gets worse. By the time you see pieces in the filter, the damage is already pretty significant.

 

I assume that the A&P in that situation would find metal in the filter, or a leak at the seal.

Since this is an art and has nothing to do with actually analyzing thing in a scientific, quantifiable way; and because I only work on one engine; and because Rotax only recommends it and gives no supporting reason or data to be followed, and because the most experienced person I know on Rotax engines of all types - Bryan Carpenter - says it has no value... the braids will get my money.

 

It's like an insurance policy. You might never need it. Unfortunately with SOAPs vs insurance, you can't tell if you did need it unless you have it and found a problem because of it. With that said, it's a lot harder to find data to justify it's merits.

 

One again, my personal thoughts on the matter, if you have an engine that's past it's break in, and want to stick to TBO rules, then there's a good chance that SOAPs will be useless to you. BUT, if you plan on using a monitoring program to go past TBO, then you should use a SOAP, and get established as soon as possible.

 

Here's some more information on Oil Analysis. http://en.wikipedia....ki/Oil_analysis

[WmInce]

I look at SOAP as sort of taking an annual "executive blood sample," for the engine.

If samples are not taken, trends cannot be identified. It's just like us. Except oil samples are a lot cheaper than my blood screens. Both of them check many things. Both of them track changes.

 

IMHO, that is what those samples are for . . . identifying trends. If the trends point to a metallurgical breakdown, like the ceramic coating in the cylinder walls, then it is in my best interest to investigate further. And if that entails "exploratory surgery," then so be it! If an owner is safety conscious, that's just part of owning an airplane. As far as I am concerned, SOAP is just part of preventative maintenance. I have personally been around it for 42 years and I'm sold on it. I have witnessed more than one engine change due to SOAP findings, specifically, Lycoming T-53 and T-55's.

 

$20 for an annual oil analysis? For anybody that owns an airplane, that should be chump change!

 

"An ounce of prevention is worth a pound of cure."

[FredG]

Among physicians, it is well known that the "executive blood sample" is generally useless or even harmful. It's not a good analogy.

 

The issue isn't the $20, it's what to do with the results that changes any operations or maintenance practices on a Rotax 912 (which, we are told repeatedly, is not a Lycoming or a Continental).

[Anticept]

I don't think continental or lycoming publishes any official oil analysis information either. It's just one of those aftermarket things that sprung up that some people use.

[Doug G.]

"Executive blood sample" may be a poor analogy, but even do it does prove a point. When I get my results back from the doctor there is a set point at which he prescribes treatment, not based on some vague art, but on research. The numbers have meaning and action is based in that meaning. Admittedly things change as more data is collected, but I would be extremely upset if the doctor said, "I really can't tell you why I think you should start taking this medicine, and I can't really point to anyone that this has helped, but it is more of an art than a science, so do it anyway."

And we have no data, no parameters, no guidelines for action... and no art school!

[FredG]

Doug, I did not mean that medical practice is a poor analogy (just "executive examinations"). Doctors are taught to order tests only when they know what they are going to do with the result. If the test result won't change anything, don't get the test. I think we agree on that point (!).