Bearfoil & BigG22
I think we are all parked pretty much in the same corner. Although RR avows there is no connection between spline wear and what happened, it may be a brave statement. One of the things that is least predictable is extraneous vibrations that can develop, particularly those that develop in the torque field. The old saying "the best laid plans of mice and men often go astray" happens more often than not when it comes to vibration. You can do all sorts of testing and analysis, but an unpredicted and unanalyzed vibration could creep in over time and affect a component/components somewhere. I don't discount the potential that spline wear could have create vibration somewhere else in the engine, like tubes or fittings, bearings/bearing support structures, the stub pipe, the plenum or even fastening devises in the torque field, including the disc power drive arm to IP shaft flange bolt holes and bolts. For instance, the bolt holes are very critical in a torque field, and generally treated with significant multipliers of stress to deal with vibration and fatigue. What if some unusual vibration or harmonics entered the equation? Is premature spline wear something you anticipate and analyze for in terms of vibrational effects? Was this anticipated in the margins provided? This is the "A leads to B" I've talked about. The experts with all of the pieces and data have to figure this out. "The spline problem has nothing to do with this engine failure" (RR statement), well I say, "Never Say Never" until all the cards are face up on the table. At this point, all the cards aren't face up on the table. Lets hope they will be, because root cause/causes of failures are only fixed by identifying them and not denying they existed at all. Oil fire and BANG are obvious, A and B are not so obvious. I don't have the answers, not seeing all the face up cards, but RR should.