Peter – I know Mike Busch and as a matter of fact was on that Webinar last year, nothing new to me, thanks for the suggestion nonetheless.
Since you reference the Webinar, you’ll notice that Oil Analysis is barely even covered, far more important to be checking screens and srubbing filter media.
Reading your own posts just go to show how useless oil analysis really is.
Reading your own posts just go to show how useless oil analysis really is.
Try the one showing how copper goes way up if the alternate air door is not closing properly.
There is a separate argument about how bad things have to be before a given owner will be prepared to open up the engine.
Try the one showing how copper goes way up if the alternate air door is not closing properly.
Why copper? I’d expect silicon to go up in that case (sand). Michael has a point about the usefulness of oil analysis. There are no clear conclusions to be drawn from it and it will very often not give you any hints about an imminent engine failure and therefore provide some false security. However, it’s not expensive and can be interesting to read. Like a fortune cookie.
I’d expect silicon to go up in that case (sand)
It did 
it will very often not give you any hints about an imminent engine failure
Will anything do that?
Try the one showing how copper goes way up if the alternate air door is not closing properly.
WoW !
That’s incredible !
Never thought about the HUGE advanatage of not even having to take the cowl off in that cold hangar to check for obvious and perfectly accessible defects that might be lurking down there !
Geez, I guess good ’ol fashioned Inspections are a thing of the past – I better get with the program ! 
I wouldn’t be so sarcastic. Please also try to make at least mostly informative posts on EuroGA.
The gap in the door was tiny and wasn’t spotted. It certainly wasn’t “obvious” – I do the maintenance with an A&P/IA and neither of us spotted it. FYI – this is the door
In that pic, the door appears closed and I can only assume that it came loose in between services – which is obviously also the oil sampling interval. And most UK aircraft maintenance companies would not have checked the door at all at the 50hr service.
This is good news of course. It would be worse if the engine was making metal for no apparent reason. Then you have to watch it, run a shorter oil change cycle, and if it continues to go up you may have to do something. Often, pulling the cylinders off will reveal that one of them was about to go.
It’s actually a very similar argument to PSA testing. Traditionalists will say that all the time you are not actually peeing blood (or have other blindingly obvious symptoms), you are good to go and will probably die of something else (which, taking the male population as a whole, is mathematically true). In this context, a chromium figure of 100 is a bit like a PSA figure of 100. Both mean that, ahem, you can’t ignore it anymore.
Foutaise ! *
Do you really think that copper from the AA door bushing somehow thru osmosis found it’s way into the oil ?
This is the REAL problem with OA : False Positives.
The scenario is EXACTLY the one you offer: Oh boy, Copper & Silicon levels are up, better go have a good look under the cowl !
After a very intensive search, a POSSIBLE culprit is found, then corrected , hooray ! thanks to OA we found it in time before catastrophy strikes !
Seriously, can you please explain technically how the copper made it’s way into the engine oil ?
ps: on this particular forum, you have been my mentor for dosing sarcasm – maybe I’m over doing it ?
ps bis: thanks for the lesson in Pharmacokinetics – always willing to learn despite 20 years in the business, ahemmm
*(English translation: rubish!)
Maybe we have wires crossed, Michael, but that is what happened. Copper and Silicon were both up, so the air intake system was checked extra carefully and the AA door was found open. The cost of oil analysis is about 20 quid which is how many minutes of your A&P time?
Sarcasm and irony don’t travel well on the internet. It’s better to make it clear to all, by using a smiley
Not out to pick a fight or to be just plain negative, but …
Agreed, dropping £20 at every oil change is peanuts, that said, what is the real value of the test results ?
Back to your AA door : Where was the copper supposed to be coming from ? I assumed that you figured it was from the door bushing but perhaps I made a false assumption ?
At any rate, just reading your posts, (particularly the title), is very telling in that there is never a clear-cut, cause / effect pattern. The scenario invariably is “something’s going on, let’s go find something” and of course, when one sets out to find something, well, they tend to find something
The copper came from increased wear of components containing copper. Bronze is copper+tin. Brass is copper+zinc.
So there is a lot of copper inside the engine, and that’s assuming you have not been using copper-loaded grease on the spark plug threads which even in tiny amounts plays havoc with oil analysis
It appears that increased ingestion of abrasive dirt (manifesting itself as silicon) wears the soft metals (bronze or brass) much more than it wears the hard ones (hardened steel i.e. iron, chromium, nickel, etc).
So a rise in copper and silicon, especially without any (or much of) rise in iron, chromium etc, suggests the air filter is damaged, badly fitting, or is being otherwise bypassed.
You could argue that a rise in silicon alone will indicate that, but you should always get a rise in copper with that.
Sure… oil analysis is rarely going to be clear cut, because most of the metals exist in multiple places, and nobody is going to ground themselves for weeks or months by removing and tearing down the engine every time there is a blip. Well, I am sure that every time the oil analysis on the engine(s) in the heli which flies the US president around goes up by 20% they do tear the engine(s) down, but nobody will do that in GA. So if you get an increase, you do the cheap and easy option which is a reduced service internal and continue to monitor it. Hey – exactly what you do with PSA Usually, the next sample shows it came back down again. It’s a good procedure because if there really is trouble at least you catch it early.
Most increases that remain within normal bounds are not themselves indicative of a problem which could cause a sudden engine stoppage. Which takes one back to asking how many people will have the balls to tear down an engine on the basis of oil analysis alone and with no fragments in the filter or the strainer… There are however poor-lubrication scenarios which will initially show up as a slight rise within normal bounds (say 2x) and could lead to a sudden stoppage. The highly respected US engine shop I have used holds the view that most catastrophic failures (on an engine that hasn’t had undeclared prop strikes etc etc) are triggered by a lube failure. You don’t need to heat up the big end of a conrod by much before it comes right off, and there is plenty of power available (250HP = 186kW) for heating things up…
Also much depends on your attitude to risk. I fly over the Alps above an overcast (albeit with a GPS running a topo map) and don’t like risk much, especially if I can reduce it for 20 quid. As an A&P, you know that most GA planes don’t get oil analysis, and it seems evident to me that maybe half the oil filters are never cut open, and probably 80% of the Lyco oil strainers are never looked at.
If I bought a plane, I would never fly it until the basics were done (oil analysis, filter cut open, strainer checked), and if I was to buy it without these being done I would discount the price by the engine overhaul cost. Especially if it was a hangar queen. (Unless it was a rare type which I just totally wanted regardless of cost, but I still would not fly it until those things were done because that’s just pointless risk – the oil filter and strainer could have “half the oil pump” in it).
The title of the thread originally referred to inconsistencies between different companies, which has never been explained. They are all vague about it. From what I have seen, across 3 or 4 of them, is that:
Blackstone (USA) and Intertek (UK) appear to use the same method and are very close. I spent a bit of money proving that…
