From CNBC:

Boeing CEO Dave Calhoun acknowledged a mistake after a door plug on an Alaska Airlines 737 Max 9 blew out, prompting the grounding of that aircraft type by federal regulations. The more common 737 Max 8 was not affected. The incident put more scrutiny on Boeing and its CEO, as the company has been struggling with defects on its planes in recent years. Alaska Airlines and United Airlines found loose parts on other Max 9s that underwent review. Calhoun said the company will work with the NTSB in its investigation and the FAA is overseeing inspections to ensure this event can never happen again.



Read more: Boeing CEO admits 737 Max 9 ‘mistake’ after midair panel blowout