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In what circumstances would one open up an engine purely on the basis of oil analysis data?

Assume the oil filter and the strainer are free of metal.

Shoreham EGKA, United Kingdom

This question is a bit strange, no one opens an engine based on 1 bad sample.
If there is no metal in the filters then how can there be so much metal in the oil? If the oil analysis is so bad then the next action is to send a new sample together with your oil filter element. If the oil sample is bed then the filter will be bed.

Last Edited by Ben at 20 Nov 17:59

Probably never. It might prompt you to inspect some part of the engine, but I am sure you would not decide to o/h solely based on one bad oil sample.


I didn’t say one sample

It might prompt you to inspect some part of the engine

Unfortunately almost nothing of a Lyco engine is inspectable. However I do understand there are variants without a dipstick in the oil filler hole, and one can stick an endoscope in there and see the camshaft, etc.

Shoreham EGKA, United Kingdom

If there are no larger particles in the oil filter and is running find, then I’d never open it.
We once had large metal pieces in filter @ only 400 hours (O-320)… had to get the engine overhauled. Back then there was no oil analysis .. so oil filters were all we had.

So what is the oil analysis for if one waits for the metal in the filter anyway?

Biggin Hill

Good question :-)
I’d say it depends, but you have to watch the oil over a longer period. My engine had a started adapter failure once and after the adapter and the starter were changed, there was lot of Aluminum in the oil analysis. One oil change later it was back to normal …
If there had been no such incident I would stil have waited another 50 or more hours.

there was lot of Aluminum in the oil analysis

How much?

Shoreham EGKA, United Kingdom

Wait, I’ll go find it …

In June 2013 at around 800 hours ALUMINUM was over 30 with a limit of 30. That one was done during the prebuy inspection. I almost didn’t buy the plane because of it but all the specialists i contacted claimed that the high AI was coming from the broken starter adapter that was changer together with the oil 23 hours earlier.

At the next 50 h inspection about 4 months later Alumimum was down to 6 again (limit 30), so i am pretty sure that it was really from the starter adapter.

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