The "bang(s)" are intriguing.
It is possible that what was heard were two separate sources of sound that happened
(close to) simultaneously.
Possibly the IT was 'slumped' (out of shape) and had fractured, but was restrained by the Shaft, although at its virtual limit of integrity.
The Stall may have been initiated by blade loss (stator contact) and reduced N2. With the instantaneous "hybrid" gas path (stall) upsetting the Disc (not to mention the entire engine/pylon), the wheel disintegrated and blew out the case. Two very loud reports, of different cause and sonic "character". One metallic, one gaseous. The pilots may have been (through experience) better able to notice the differing character of each sound, even with "simultaneity". It would explain the final impetus of the Disc failure, especially in light of the Miami machine's retention of disc "integrity" sans "Stall". I don't think it necessary to include overspeed as a component.
Oil Fire certainly would account for added heat, but logically, the heat would be somewhat erratic, and the mode of failure of the wheel is described as 'patent',eg 'in three roughly equal parts'. If true, that would suggest less than a chaotic heat soaking due to fire. A more blended heat soak (evenly distributed) would most likely have been the result of friction at the Drive Arm/Stator (who brought up 'fluid bearing?).
Most important, metallurgically, then, would be a determination of the "Point" of failure, whether Rim (Fire), or Drive Arm. The chronology of the event suggests to me, a 'build' of heat, something I would relate to a slow "Migration" of the Wheel, and a concomitant elevation of Oil temp. It sounds counterintuitive to describe this "failure" as 'gentle' in any way, but a slow build of heat through the structure seems more accurate, given the timeline, than that engendered by something as chaotic as Oil Fire.
Whether the Stub Pipe was born wrong or wore through, its failure appears gradual, and conforms to worries announced in the ADs. Though a three shaft powerplant, any insufficiency of bearing performance at one location, translates immediately to the other bearings. The vibration record (both power and timing) is truly mesmerizing, and tells a tale.
Last edited by bearfoil; 28th Dec 2010 at 14:28.