Andrew: All of those suggested causes relate to design, manufacture and maintenance. Surely it can only be the way the pilots are operating them that is causing the damage? (Just kidding. I added that just to goad yr right.)
Assuming that the cause/s is/are one or more of design, manufacture (including assembly) and maintenance, I’d still run the engine at the settings at which it’s getting the hardest pounding I could give it (40 to 50 ROP, lower RPM). That would also mean the thermal cycle would have the highest peaks.
I suspect most engine manufacturers are on top of that, and already perform similar tests.
You may well be right, but I wouldn’t be surprised if you aren’t. Testing at those settings assumes that manufacturers know that they impose the greatest stresses on the engine. If they knew that, it’s hard to explain why some POHs (albeit old ones) would still recommend operations at those settings. Sure, it’s the setting that will make the aircraft cruise very fast, but it’s not fun for the engine.
