Sampling of course, but at the weak point of the part? With potential for corrupting the failure's site? An artifact that suggests "Machining", rather than Sampling? I take your point of course, but again, I see a concentric with the "defect" (wear?) in the bore!!
For me, I try to imagine what is not present in the evidence that may have played a part in failure, so bear with me. The RR architecture is supposedly proprietary, so at this point, we may not see more.
If there was an "Aspirator" on the tip of the Stub, and it fouled, it would have created extra drag on the oil pump. The "Swirl Marks" on the tip may be an artifact of siezed ball bearings, having contributed heat of failure to the wear's face. If the Oil was under Pressure of delivery, the load would be absorbed by a ball bearing contact. Again, I think the Concentric orientation of the tip defect with the bore "Ledge" is telling.
bear
Last edited by bearfoil; 5th Dec 2010 at 16:25.