landing. tom, what in the world happened here? reporter: it now appears that one of the fan blades on the engine there are 24 blades in a turbo fan engine. one of those fan blades broke off at the hub, at the base. the ntsb now says there are signs of metal fatigue. when that fan blade broke off we had what was called an uncontained engine failure. in other words, it didn t stay within the housing of the engine. entire thing came apart hurling the shrapnel into the plane and then blowing out that window and sucking that passenger part way out the window. just absolutely horrendous. this is the first fatal accident involving a u.s. airliner since 2009 and the first onboard fatality ever for southwest airlines. so now the concern is that this may be a problem that the other airlines who also run the 737 need to be concerned about. southwest has 700 737s, all of them with the same engine.