The Boeing 737 MAX 9 airplanes have been grounded due to a design flaw. A door plug on an Alaska Airlines Boeing 737 MAX 9 came off inflight, resulting in rapid depressurization. The plug was manufactured by Spirit AeroSystems in Malaysia. Many 737 MAX 9s have been inspected, during which some have had loose door plugs, raising concerns about a potential design issue.
This issue is possibly due to structural flexing of the aircraft caused by the heavier engines of the MAX 9 model. If the cause of the loose door plug is unidentified, then frequent inspections would seem necessary so as to assist in identifying what is causing the bolts to loosen on planes. Several questions about the aircraft type remain, and it may be necessary to consider greater reinforcement to correct the situation. There are still a lot of questions about the aircraft type that remain to be addressed.