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