Bearfoil
My Quote:
Assuming the disc began to stretch, because of overspeed and presence of higher than designed for temperatures in the bore area, the turbine blades could have started to unlatch at the tip shrouds.
In this post I was responding to another quote on how the IPT blades could have failed without physical contact with other neighboring components. It was not an attempt to explain the total failure, where it started and how it progressed.
But, in that you brought up the subject of the disc:
isn't the better assumption that the Disc Fractured after contact with Stationery Parts, melted, Disintegrated, and caused burst?? I see no need to entertain Fire, or Blade shear to explain this Engine Explosion.
Take a look at the photos of the recovered section of the IPT disc in the ASTB report. In the fracture surface photo, note the structure close to the bore on the
forward side and the shape of the bore surface forward to aft.. In the photo of the rear face of the disc, note how one turbine blade root seems firmly in place, but another has a significant gap present in the corresponding disc slot and there is no indication of metal to metal contact at the disc rim or blade slot area. Also note the ductile bend of the power arm drive where it is present.
Now think about something, what are the two elements required to
permanently form or deform metal where the normal material ductility is less than 10%?