may I point few things here. as far, as I heard about the case, the pilots heard no 'bang' on flight deck on TO, the 'bang' message came from the CC. How loud was the 'bang' its a personal sense of the people involved. I heard few RTs when pilots reporting severe turbulence flying through a moderate one. few birds, I run over did a loud bang as well, that could be one of the reasons. at some altitude the guys got TAC on EICAS, while both ENGs were turning, and some time later IPR blanked, and the ENG EEC came on. all NNCs were done, and both ENGs had very similar indications. the RWY inspection was done with no findings, and a visual inspection of both engines was done inflight, as far, as you can see them at night trought the wing. apparently both of them were hanging below the wings with no visible damage. the crew was aware, that something has happened to the ENG, but not the extend of the damage, all available gauges were indicating the right ENG is turning in ALT mode as smoothly, as the left one. I guess, at this point everyone has a choice to continue, or dump fuel and return....