Chu Chu
Could the second bang have been the disc segment hitting the wing?
I agree with
bearfoil. It would appear the disc separated into 4 pieces, the largest being the 135º section recovered. It must have exited the engine downward and to the left based on its recovery point. the other three pieces exited to the right as defined in the ASTB report's diagram.
The recovered piece weighed almost 70 Kg, 150 Lbs. So the total weight of the disc alone, minus the turbine blades approached 400 Lbs. or more.
It was probably rotating at a speed of 7,000+ RPM at the time of failure.
The sound of breakage and the energy released is so immense it would overcome any sound of the pieces going through the wing.
Also, watch the video on compressor stalls and the noise created by the explosion of the gasses going forward and aft, that was in one of my previous posts, the site is given below.
YouTube - pt. 2 of 3 Turbofan Jet Engine failure recognition