the report of visible flames etc. coming from the back of an engine and he maintains that usually indicates "shelling" of an engine; ie: the expulsion of blades resulting from an uncontained or contained failure.
What nonsense is this now? Have they never seen a video of an engine surge? Massive fireball but certainly no shedding of blades. If an engine surge was indicative of blade shedding with damage to the rear fuselage from molten metal spray I think we may have seeen a lot more damaged aircraft over the years. I don't know what engines NWA use but I don't recall any incidents involving an RB2111 spraying molten metal over the rear fuselage, and we've have a lot of engine surges on the three fleets we use those engines on.