#1 the gasses come at the velocity of a rifle shot
How fast do you think a piece of turbine wheel is going?
#2 I would go with fractured apex, or blown corner seal.
There were no missing parts of apex or corner seals. All were intact and in place.
BTW John did not find any corner seals left when Bruce opened the engine
It was the little rubber things that were missing, not the corner seals.
By the way, just in case there's any confusion, we're talking about turbo failure # 2 here, not the latest one.
John