I suggest that once the circumferential fracture separated the wheel from the power arm, the disc was already exceeding a (somewhat lower) burst speed.
Are we looking at the same schematic? The turbine disc has "return" (sleeve) feature that is the drive arm. The circumferential fracture separated the wheel from the arm, therefore the wheel is no longer restrained in a circular orbit. Show me where the wheel has any interest whatsoever in accelerating? The massive pressure of the exiting HPC gases thrusts the wheel instantly into the LPT Stator. The turbine blades are sheared, and the wheel performs a very rapid eccentric dance out the case, post disintegration. Attached to nothing, how do you say the wheel remains stable to resist the flow of gas, and thus accel? It has no axle. No stability.
Lomapaseo. A rapidly spinning bicycle wheel illustrates exactly my point, its gyro expression of high energy slams it into the stationery parts of the core.
I still suggest that the slowing of the IPC demonstrates the axial migration of the IShaft aft ward into the "stationery parts of the engine" (AD). Integrity of the shaft is required until disintegration of the I Turbine, IMO. I suggest that this slowing of N2 (evidence from phonic wheel, and diminished pressure), is what precipitated the introduction of extra fuel into the burners, and caused N3 to increase, perhaps even introducing unburned Fuel into the IP cavity. That can't be a good thing...
How did one quart of oil incinerate this engine?
Last edited by Lyman; 9th May 2012 at 00:45.