Originally Posted by
andrasz
Looking at the pic of the window it appears that the piece of shrapnel did not penetrate the outer pane but came in at an angle, puncturing the skin adhacent to the window frame and then shattering the inner pane.
Rough calcs I did at uni.. a single HP turbine blade has the same Kinetic energy as a 20mm round if it separates at the root. Takes a lot of containment to keep it all in, plus to keep a massively unbalanced core from shaking itself to bits, even if the FADEC catches it and commands an auto shutdown. Bit like a washing machine with a concrete block in it.
Could equally have been something heavy from the cowl, for example a big lump of bleed air valve for the engine ice kit, even if the blades had been contained.