Shares of Boeing Co. dropped Monday, after the Federal Aviation Administration recommended more aircraft models of the aerospace giant should have their door plugs inspected. “As an added layer of safety, the Federal Aviation Administration (FAA) is recommending that operators of Boeing 737-900ER aircraft visually inspect mid-exit door plugs to ensure the door is properly secured,” the FAA said on its website. The 737-900ER is not part of the new Max fleet, which had the door-plug issues that led to the ...