barit1
#1 Unwanted in the sense of being incompatible with the engine's normal operation, not simply a burden on FFC.
#3 Pressures exclusive of Gas Path?? The seals at the Bearing cavity were lost, and the possibility exists that they didn't "burn up", but were blown out (hence chaotic) ??
Also, as I understand it, the scavenge tubes are pressure sensitive, to allow a compensating Pressure to enter the tube "without combustion", if the tube fractures, as is quite common in other types also.
The 2003 Failure of the TRENT 700 IPT was exacerbated by the existence of fire in the Gallery vents. the feed tubes transit the Gas Path, and I am unsure of the position of the Coupling, but a compromised couple would hasten ignition?? Not to mention loss of Oil??
Fuel Flow might be noticeable. My take on this fire is that it was quite rapid after reaching a certain value, and the remedy was past its effective timing?? To mean that it may have been burning, but once the coupling failed (if it did), the loss of the disc may have taken only another ten seconds.
At "Turbine OverHeat" (alert), The First Officer started his 30 seconds of monitoring w/o action until the Fire Warning lit, then the screen went back to OH only, and he re-started the Timer. The Fire Warning may have been the onset of fully Oil fed Fire, unknown as to why it may have relented.
#4 By irregular loads I mean to say the Plastic character of overheated Metals, and the Friction induced disintegration of bearings, perhaps caused by Siezeing, due the Heat of the Oil Fire. I think it possible that there was fire in both sets of bearings, IP/HP, the Ball and Rollers. There is no evidence of fire on the LP shaft in its cavity with the IPT, but the Pressure here was much greater than that in front of the IPT??
I think the 'assumption' of Normal Temps and Pressures maintained by the FFC is difficult to make, given the probability of rapid failure? It certainly is not intended to "normalize stress" during an Oil Fire?? So I think juxtaposing a "Normal" set with an abnormal one has time limited value? I definitely would not reject the idea that FFC action could mitigate abnormals while the Oil Fire was "maintaining" a "steady" burn rate??
I definitely agree that #4, and #5 are either/or, to include pre/post.
Have you had a chance to see the Soot on the LP aftShaft?? It is a slow process for me, to try to grasp the architecure of this engine and entertain a failure such as this, it is a complex machine, to me.
rgds.