 It says Boeing also speculated about the cause of a door plug blowout in January, indicating an employee's work may have been responsible. The NTSB says it's focused on the probable cause of the incident, not placing blame on any individual. Boeing could now face criminal charges over the matter. July 4th's a week away, but today is expected to be the busiest air travel day of the year so far, as FAA Administrator Michael Whitaker told...