Summary: Boeing remains on the hot seat over questions about its production processes. The head of the National Transportation Safety Board told lawmakers her investigators still don't know who worked on the door panel that blew out of an Alaska Airlines flight. Meanwhile, NYT reported Boeing and a key supplier failed a number of audits. Aviation correspondent Miles O'Brien spoke on what went wrong. PBS NewsHour is supported by - https://www.pbs.org/newshour/about/funders
