How do you know you it's time for an Engine Overhaul?

timwinters said:
Mr. Busch tries hard to convince his followers that all A&Ps are out to screw the average owner and that they can't be trusted.
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I challenge you to cite a Mike Busch quote that includes the key phrases "all" and "screw" and "can't be trusted", as used to describe aircraft mechanics.

I am quite certain you will be unable to find one.
 
NoHeat said:
I challenge you to cite a Mike Busch quote that includes the key phrases "all" and "screw" and "can't be trusted", as used to describe aircraft mechanics.

I am quite certain you will be unable to find one.
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Well, of course he doesn't use words like that. He's a bit more subtle and uses statements such as "In addition, Savvy can be a godsend when you face an aircraft owner's worst maintenance nightmare: a mechanical problem away from home. Instead of having to deal with unfamiliar shops and mechanics, you simply contact your Savvy account manager and he handles everything for you. He'll ensure the problem is diagnosed properly, that it is repaired in the most cost-efficient fashion, and that the charges are fair and reasonable. That kind of peace of mind is priceless."

That says pretty much exactly what I said. That the shop will take advantage of you without Savvy in your corner.

And...of course...Savvy will be able to correctly diagnose the problem from 1/2 way across the United States while the mechanic who's looking at the plane can't. :rolleyes2:
 
Timwinters, I think that exact sort of scenario is the one where the ignorant owner is most likely to get screwed. If you have a regular A&P, the A&P will usually know that to maintain your loyalty, he'll need to moderate his charges. So he moderates short-term gain for the sake of the long-term relationship. But if you are broken down at a remote airport far away from home, you are in a time sensitive position and the local A&P knows that he will likely never see you again once you fly off. It's in his long and short-term economic advantage to inflate the cost.

That's not to say that every A&P would do that, or that Savvy fully protect against it happening, but you cannot argue that the odds of it happening vastly increase when you are in that very scenario. That should be practically indisputable because it's based on just general business principle. I'm just a new pilot with 50 hours under my belt, but it also seems like the points he makes in a lot of his webinars are probability oriented, and probability is something that every pilot should be aware of since our lives when we fly depend so much on the compounding effects of probability.
 
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If you own an aircraft, and have a good relationship with your A&P, then he/she can/will provide you with just as, or more, capable consulting services if you break down away from home...and for far less than the cost of an annual. Most likely for free...or a dinner.

I guess I still remember far too many debates from ten years ago or so when Walter Atkinson and George Braly would regularly hand Mike his a$$ over at CPA (and/or AOPA). My favorite was when Mike asserted that you should never stop at the SS pump upon your return home to fill up. You should instead taxi to the hangar and call the fuel truck. You'll save money, even though the gas is higher, because every start up imposes excessive wear and tear on an engine, even one that occurs within 15 minutes of shut down when everything is still warm. :rolleyes2:

He finally conceded that one.

And there were many more fun discussions had in those days. Cry wolf too many times and I lose faith.

He's a great salesman though.

OTOH...Braly and Atkinson...now there's two people whose word you can take to the bank.
 
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Oh, and this one was so good I had to go back and find it. This was from January 2004 and was Mike's response to someone who was worried about their oil temps not getting warm enough in the winter to boil off the water.

Keep in mind that when it's that cold out, the air is usually quite dry and the buildup of moisture in the oil is a lot less. So I wouldn't obsess about this.
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(Page 1076 mx matters)
 
timwinters said:
Oh, and this one was so good I had to go back and find it. This was from January 2004 and was Mike's response to someone who was worried about their oil temps not getting warm enough in the winter to boil off the water.



(Page 1076 mx matters)
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:rolleyes2: What does a hydrocarbon turn into when oxidized? Oyy There have been a couple of threads here that have caused me question on his operation.
 
Omalley1537 said:
I think that while this a great point, there is another facet to consider, which is you cannot truly quantify how many failures were prevented due to maintainance that took place due to an issue with the oil analysis. In other words, there are certainly catastrophic failures that gave no sign of impending destruction via oil analysis, but there are likely many averted due to an issue at analysis time that was dealt with.
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I'm going to estimate: almost none. Oil analysis has an unknown number of false negatives and false positives. When your oil analysis shows something abnormal, no one knows what to do about it. It generates uncertainty and causes unnecessary expense. Worse than worthless, I say.

When to OH? Things that really matter are oil consumption, borescope, perceived power ("just doesn't seem to climb like it used to"), cut oil filters, and an educated eye poked into any coincidentally opened hole (e.g., the alternator in a Continental 520).
 
Tom-D said:
oil analysis tells you when it has failed.
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no.....it doesn't.

It tells you when it's making metal, which may or may not be an "indicator" of impending failure. :nono:
 
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Tom-D said:
There is only one reason in part 91 to overhaul any engine, that is, you no longer trust it. And that is based upon a variety of reasons.
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yeah.....but, I'm waiting for Henning to tell me to do the OH. :goofy:
 
Stuart Fraley said:
I'm going to estimate: almost none. Oil analysis has an unknown number of false negatives and false positives. When your oil analysis shows something abnormal, no one knows what to do about it. It generates uncertainty and causes unnecessary expense. Worse than worthless, I say.

When to OH? Things that really matter are oil consumption, borescope, perceived power ("just doesn't seem to climb like it used to"), cut oil filters, and an educated eye poked into any coincidentally opened hole (e.g., the alternator in a Continental 520).
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Very well said!
 
Stuart Fraley said:
I'm going to estimate: almost none. Oil analysis has an unknown number of false negatives and false positives. When your oil analysis shows something abnormal, no one knows what to do about it. It generates uncertainty and causes unnecessary expense. Worse than worthless, I say.
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Customer came in with oil analysis showing high bronze. No power loss, no compression loss, no change in oil consumption. Running perfect. Changed oil and came back 10 hours later with new analysis. Same result. Pulled engine for inspection. No obvious signs of any problems. Turns out a valve guide was moving but only in very specific conditions. It would move up and then get hammered back into place by the keeper. There was no sign of bronze under the rocker cover. 99/100 times a problem like that would also have compression or oil consumption problems.

So feel free to tell the pilot of the crop duster that his oil analysis was worse than worthless. People wonder why their engines have extra charges added on at OH time. It's because they ran parts until failure and their core is worthless.
 
Stuart Fraley said:
I'm going to estimate: almost none. Oil analysis has an unknown number of false negatives and false positives. When your oil analysis shows something abnormal, no one knows what to do about it. It generates uncertainty and causes unnecessary expense. Worse than worthless, I say.

When to OH? Things that really matter are oil consumption, borescope, perceived power ("just doesn't seem to climb like it used to"), cut oil filters, and an educated eye poked into any coincidentally opened hole (e.g., the alternator in a Continental 520).
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Not worthless, oil analysis provides considerable relevant data. No decisions are made from a single reading, oil analysis on its own is primarily used to track trends, and it is those trend lines that give us the data to consider.
 
Oil analysis is roughly analagous to a blood test. It indicates things that you may want to look more deeply into, or monitor further.
 
I apologize for the thread drift. But, regarding oil analysis, I think it adds only confusion. Here's why:

Imagine the following scenarios:

1) Oil analysis shows high iron. Cut filter has a large amount of ferrous metal.
2) Oil analysis is completely normal. Cut filter has a large amount of ferrous metal.

3) Oil analysis shows high copper. Borescope shows a burned valve.
4) Oil analysis is normal. Borescope shows a burned valve.

5) Oil analysis shows high levels of copper, iron, phosphorous, and molybdenum. Cut filter is normal. Compression check is normal. Borescope is normal. Oil consumption is unchanged. Performance is unchanged.

Situations 1 and 3 are obvious: There's something wrong and the engine needs work. 2 and 4 are also obvious: There's something wrong and the engine needs work.

But what has the oil analysis added in 1-4? Nothing.

Then there's #5, which is distressingly common. Abnormal oil analysis has cost our hapless airplane owner hundreds of dollars so far. He's instructed to "go fly 10 hours and repeat the oil analysis." Can he trust this engine? If he lives in the mountains, should he really be flying his 10 hours close to home? Should he fly in IMC? Over water? So he sends another sample and it's either normal or it isn't. If it is, does he trust this engine? How does he know which analysis to believe? And if it's abnormal, what does he do now? He's already done all of the nondestructive testing. Does he start pulling jugs? Crack the case? Post to POA and follow the advice of trusted strangers?

This is why I say oil analysis is less than worthless. It either confirms what you already know or it adds confusion and expense. In my own case, I overhauled a 500-hour engine after Blackstone informed me, "This Continental seems to be aging like a fine wine." So, there I was, crossing Lake Michigan in an airplane who's engine was making more metal than US Steel, secure in the knowledge that my engine was superbly healthy.

Too many false negatives. Too many false positives. Completely unknown predictive values. Oil analysis contributes less than nothing to the question at hand, which is, "How to you know it's time for an Engine Overhaul?"
 
I find things in oil analysis that don't show up in filters. Oil analysis finds the ferrous as well as other metals before they get big enough to show in filters. Then there are also various chemical traces that tell me I have a ring seat issue and a blow by problem. Oil analysis can tell me if I have hot spots in my engine....
Oil analysis provides a lot of data. Oil analysis provides no definitive data, but it provides a buttload of initial and supporting data.

What oil analysis allows you to do best is preserve the core value of your engine, and that is a not insignificant number.
 
RalphInCA said:
Oil analysis is roughly analagous to a blood test. It indicates things that you may want to look more deeply into, or monitor further.
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bingo.....:yes::thumbsup::wonderwoman:
Stuart Fraley said:
I apologize for the thread drift. But, regarding oil analysis, I think it adds only confusion.
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Stuart....oil analysis is but one of "many" tools that "can" indicate an impending failure. Those indicators are dependent on the physics of failure.

How is the part failing?
* Is it making metal or material? ....is it particulate fine or are they large chunks?
* Is the part experiencing fatigue? ....and forming cracks, increasing stress?
* Is the part wearing slowly?
* Is excessive heat involved?
* Is the part arcing?
* Is the part not sealing pressure (oil or pneumatic)?
* .....etc

Until one can determine how this part does not perform its intended function and how it fails.....one can not say oil analysis is useless.

I'd never expect oil analysis to "indicate" or warn on an impending electrical failure....unless there was some mechanism that indicates using that test.

For example, on my electrical system I have a gear driven coupler that drives the alternator. It isolates the alternator from the engine. If the coupler begins to slip it could make "material". If those particles are not metal, because some couplers are non-metalic and too large.....oil analysis wouldn't show a thing, but the oil filter and sump should be loaded with the red material.

If those parts are metal....oil analysis still might not indicate. Large particulate, particulate that are too big (shavings or chunks), will not be in suspension in the oil. Those particles will sink, not float in the oil and gather in the bottom of the sump and possibly gather in the filter.

However, if the parts produced by the coupler are fine metal or material, oil analysis will indicate an elevated particulate with the composition of the material. It's up to the one reviewing the analysis to determine where that material is used inside the engine....then investigate the source.

So....blanket statements about oil analysis are ignorant without the knowledge of the physics of failure.....and how those failures indicate.

Determining the health of an engine requires monitoring many parameters and not fixating on just one. Some are operational, real-time data gathering, others are latent inspections. Like checking sump screens, oil filters, and performing oil analysis....or better yet, performing an internal and external visual inspection using a low cost USB borescope camera.
 
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Checkout_my_Six said:
Determining the health of an engine requires monitoring many parameters and not fixating on just one. Some are operational, real-time data gathering, others are latent inspections. Like checking sump screens, oil filters, and performing oil analysis....or better yet, performing an internal and external visual inspection using a low cost USB borescope camera.
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Many simply use the Manufacturer's recommended number.
 
Checkout_my_Six said:
Stuart....oil analysis is but one of "many" tools that "can" indicate an impending failure. Those indicators are dependent on the physics of failure.
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But when oil analysis indicates a possible impending failure, what's the likelihood that a failure is, in fact, impending? No one knows.

So....blanket statements about oil analysis are ignorant without the knowledge of the physics of failure.....and how those failures indicate.
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I am many things, some despicable. But in this case I'm not ignorant.

Determining the health of an engine requires monitoring many parameters and not fixating on just one. Some are operational, real-time data gathering, others are latent inspections. Like checking sump screens, oil filters, and performing oil analysis....or better yet, performing an internal and external visual inspection using a low cost USB borescope camera.
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No argument here, except that I fail to see how oil analysis adds anything but confusion and expense. Good point about real-time data gathering. Some of the best information comes from a multi-probe engine monitor.

I've described several common scenarios in which oil analysis adds nothing or less. For the life of me, I can't think of a single one where it's helpful.
 
Ever hear of a doc saying, as the result of your blood work labs, you're gonna die? I'd take the same advice from an oil lab, and have the same reaction.....it's an indicator to investigate, not to do a knee jerk and go into overhaul mode.

I'm sorry if I've offended you.....I didn't intend to, but if one doesn't understand the physics of failure and the indicators....then I totally get your comment "oil analysis adds confusion".

Please don't fixate on the oil analysis as an end all be all. It isn't. It is but one of many tools in the mechanic's tool box used to determine engine health. Lots is written regarding condition monitoring across many industries. It has it's place if one knows what to do with the data.

Stuart Fraley said:
But when oil analysis indicates a possible impending failure, what's the likelihood that a failure is, in fact, impending? No one knows.

I am many things, some despicable. But in this case I'm not ignorant.

No argument here, except that I fail to see how oil analysis adds anything but confusion and expense. Good point about real-time data gathering. Some of the best information comes from a multi-probe engine monitor.

I've described several common scenarios in which oil analysis adds nothing or less. For the life of me, I can't think of a single one where it's helpful.
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So, if I don't agree, then the only answer is my ignorance? How silly of me to take offense.

Would you describe a real-life scenario in which oil analysis contributes in a meaningful way? I ask sincerely, as a false-negative oil analysis could easily have led me down the primrose path into the bottom of Lake Michigan.
 
Stuart Fraley said:
So, if I don't agree, then the only answer is my ignorance? How silly of me to take offense.

Would you describe a real-life scenario in which oil analysis contributes in a meaningful way? I ask sincerely, as a false-negative oil analysis could easily have led me down the primrose path into the bottom of Lake Michigan.
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It depends on what metals are indicating in the analysis......

I'd take that information and look at the oil pressure and the pressure response and maybe draw from that. I'd also probably do minor surgery before major....by removing parts to have a look see inside at likely areas, before committing to open heart surgery.

Honestly.....unless I saw piles of shavings and filings in the sump and or filter I prolly wouldn't get too excited with what the experts at the lab were barking.
 
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Stuart Fraley said:
Would you describe a real-life scenario in which oil analysis contributes in a meaningful way?
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Engine log indicates 50 hours in the last 5 years. the tach says 10 in the past year.

next oil sample shows excessive high iron. What's happing ???
 
Tom-D said:
Engine log indicates 50 hours in the last 5 years. the tach says 10 in the past year.

next oil sample shows excessive high iron. What's happing ???
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That's a great example. You wouldn't have that datum by itself, so what about the other stuff: Filter, borescope, compressions, engine analyzer? If they're not normal, oil analysis didn't add anything. If they're normal, then what? Go fly, worry, and recheck? Then it's normal or it's not. If it is, you say, "Ah, I'm just knocking the rust off." So, what did the oil analysis add? But if it still shows high iron? Everything else is normal, so do you start pulling the engine apart to find a source? Maybe it's the oil filler cap (it's happened), which you might never figure out.

That's all I keep saying: any information that might be gleaned from oil analysis is available more conclusively and less obtusely elsewhere in a standard maintenance program. When the oil analysis and other tests agree, OA has added nothing. When they disagree, which is common, people generally wind up doing what the non-OA data would indicate. Again, no help from Blackstone.
 
Stuart Fraley said:
That's a great example. You wouldn't have that datum by itself, so what about the other stuff: Filter, borescope, compressions, engine analyzer? If they're not normal, oil analysis didn't add anything. If they're normal, then what? Go fly, worry, and recheck? Then it's normal or it's not. If it is, you say, "Ah, I'm just knocking the rust off." So, what did the oil analysis add? But if it still shows high iron? Everything else is normal, so do you start pulling the engine apart to find a source? Maybe it's the oil filler cap (it's happened), which you might never figure out.

That's all I keep saying: any information that might be gleaned from oil analysis is available more conclusively and less obtusely elsewhere in a standard maintenance program. When the oil analysis and other tests agree, OA has added nothing. When they disagree, which is common, people generally wind up doing what the non-OA data would indicate. Again, no help from Blackstone.
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well....I wouldn't say it added nothing.

It's information that "flags" an investigation to answer a few questions. Once one is comfortable with the answers, one is armed and can make a plan. Keep flying and recheck at a later time?....remove and replace part XYZ?.....or dig further?

IMHO....it's no different than a check engine light....with an error code.

I'm very much a "if it ain't broke don't mess with it" kinda guy....and I need proof before I'll tear into an engine too far.
 
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Yep, engine oil analysis is worthless. That's why every major trucking company that I've been associated with (FedEx Freight, Watkins, Viking, American Freightways, etc.) does oil analysis at every oil change on every tractor.

They just love throwing money out the window on worthless things.

:rolleyes:
 
timwinters said:
Yep, engine oil analysis is worthless. That's why every major trucking company that I've been associated with (FedEx Freight, Watkins, Viking, American Freightways, etc.) does oil analysis at every oil change on every tractor.

They just love throwing money out the window on worthless things.

:rolleyes:
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Diesels running synthetics, never change oil, just the filter and add oil. and run a trend to see when the oil is breaking down.
 
arguing over theory. How about answering the OP from your own experience. What has made you personally pull the trigger and overhaul?
 
Stewartb said:
arguing over theory. How about answering the OP from your own experience. What has made you personally pull the trigger and overhaul?
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We pulled the alternator for IRAN. The ring gear (inside the case) was badly worn. Cut filter showed lots and lots of metal. It was so bad that I had to get a new crankshaft and camshaft, all at 500 SMOH. So, it had been going bad for some time.
 
Stewartb said:
How about answering the OP from your own experience. What has made you personally pull the trigger and overhaul?
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Every thing in the engine seemed to be worn out, and the engine would not make minimum oil pressure at idle, records showed 3200+ since last overhaul, SO I didn't trust it any longer.
 
Stuart Fraley said:
We pulled the alternator for IRAN. The ring gear (inside the case) was badly worn. Cut filter showed lots and lots of metal. It was so bad that I had to get a new crankshaft and camshaft, all at 500 SMOH. So, it had been going bad for some time.
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There is no such thing as a ring gear inside the engines we see in GA. Unless you have one of the very few engines with a planetary gear reduction systems on it.
 
Whatever. It's a circular gear that goes around the crankshaft and provides power to the alternator. Call it what you want.
 
the ring gear is typically what folks call the thingy that the starter drives on a Lycoming....and it's external to the engine and bolts between the prop and crank shaft flange.

20130720_timing_mark2.jpg
 
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Checkout_my_Six said:
the ring gear is typically what folks call the thingy that the starter drives on a Lycoming....and it's external to the engine and bolts between the prop and crank shaft flange.
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Not on a Continental, it's inside the accessory case.
 
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