Originally Posted by
CarlOrton
A good lab will reference your sample against fleet averages. Yes, ideally they will know YOUR engine better after several samples (to develop trending data), but one sample can still be compared to other similar engines.
When you submit a sample, you typically provide info on hours on engine, engine type, hours since last oil change, etc., so they can adjust the results in comparison with other like engines.
Regarding the types of material found in a sample, they will give a broad-range guess as to the source. As an example, they can determine the alloy. So, iron with nickel in it would come from a different component than iron with [insert metal here].
Most labs are relatively small, so if you document your unique situation (low avg run times, pre-buy, etc.) they can tell you that while a given material may be high in comparison to the fleet, x hours of flying is typically found to reduce those values. They're really pretty good forensic investigators!