lomapaseo
I disagree, though with a caveat. Friction as heat won't melt the disc, (nor would much). Friction is my candidate for the instantaneous lock, IPT to Shaft, that loosed the wedges of Wheel we see (actually just one that was found thus far) through the engine's casing. I say this because I notice an "undamaged Perimeter" of the "Wheel". Without Blades, its makes no thrust, and is not affected by airstream reversals. The loss of the wheel was concentrated on the Hub, and Shaft face, it's where the Wheel "Broke Apart". So Heat, Oxidation, and Humungous Centrifugal force at the Hub/Shaft, Bearing Seal, Etc.
Think "Friction Stir". Focal Temps at the join of two dissimilar metals can be quite alarming.
Your comment re: "Keeping the Oil in its place". Natch. Please let's don't entertain a fix that involves placing drums under the 2nd Stage at each Gate, not like the "earlier" 'Pratts'
. Beyond my pay Grade, but if the fix is a mitigation composed of "Seal, Relief, Return and Oil Delivery" Mods, then nothing of grave concern presents. RR makes Primo Power, always has, always will. If SIA is only swapping three, where did the spares come from? Assuming that if it is the same glitch (as the 972), the repair may be 'simple' and 'straightforward'.
cheers,
bear