Simply a thought, but the size of these latest Turbofans may want a new manufacturing process, a way of preventing unpredictable (chaotic) failure. It would be wicked expensive, and the risk/benefit may not pencil out, but:
A peened pattern on the surface, concentric circles etched in the disc (both sides) intersecting "spokes" proud of the surface, such that each intersection of relief, proud, defines a failure ring and segment. It would weaken the structure (requiring extra weight to solve this) , but would theoretically provide a predictable and sequentially more robust failure zone, until the hub and inner portion are protected from further fracture/loss. It would command a completely new test profile, a "blade, partial, complete sequence".
Mr. Pratt? Mr.Whitney? How is the lawsuit coming against further import of the RRTrent1000? The 787 suffers as we speak, PW are claiming patent infringement. Or is it a red Herring? Has Boeing actually solved the ripples?
bear