Without going into detail, I have seen a number of the MAS props come apart. Yes, and elevated rpms that most r/c pilots do not see. Kinda something you end up seeing now and then with engines and testing stuff. Prop makes a god awful sound just before it lets go.
I have seen a few prop failures at the local fields over the years. They are rare.
In some cases, ambient air temperature may have had to do with it (plastic / nylon does weird things when cold)
In other cases, folks over-tightening the prop likely cause the failure.
In those cases, RPM was not a factor - all sport engines.
I think Duane has seen this too..... on APC props, you can visibly see fatigue in the blade. When one of the props develops a white haze look on the blade surface, usually toward the tips, its time to toss it into the garbage. They can and do fail, but they tend to give fair warning
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