frequently, probably, than we all care to recognize. they re very reliable, but often when they fail, they re designed to fail so all the parts stay internal or go out the tailpipe and not cause any further damage, making it sort of a non-event which is why we don t hear about it so much. every now and then, though, you get a contained failure in which some piece or part escapes from the cowlick of the engine, and essentially those are pieces of shrapnel that come off at very high rates of speed and can easily pierce the skin of the aircraft. we ve had some initial reports that that might have happened in this case very early. i remember back in the mid himi, i remember a delta flight in florida, actually happened in pensacola, where an uncontained engine failure there caused the death of a passenger as a