Last week's near-catastrophe involving a Boeing 737 is drawing fresh scrutiny of the company and its manufacturing, quality control and safety practices.

The big picture: Boeing had been trying to revive its once-sterling reputation ever since a combined 346 people were killed in crashes involving its 737 MAX 8 in 2018 and 2019.

• But then Alaska Airlines Flight 1282 — a Boeing 737 MAX 9 — returned to Portland International Airport shortly after takeoff last Friday after a "plugged" emergency exit door flew off, exposing passengers to the open air.
• The aircraft landed safely with no fatalities.
• Aviation regulators grounded the MAX 9 fleet amid investigations. The Federal Aviation Administration on Monday approved an inspection process for the airliners, a critical step toward getting them flying again.

The latest: United Airlines has "found instances that appear to relate to installation issues in the door plug — for example, bolts that needed additional tightening," the carrier said Monday afternoon, suggesting a potentially widespread issue with the model.

Between the lines: After the deadly MAX 8 incidents, pilots, safety experts and others criticized Boeing for failing to adequately explain a system designed to counteract the aircraft's nose-up tendency in some situations.

• The need for that system stemmed from Boeing's decision to quickly modernize its 737 lineup in response to growing airline interest in rival Airbus' competing aircraft, rather than spool up an entirely new design.
• Thus the MAX lineup — which Boeing pushed as just another version of the 737, despite considerable changes — was born.

While no airplane is perfect, the MAX program has had its share of issues even beyond what caused the 2018 and 2019 crashes.

• For example: Boeing recently asked the FAA to exempt the MAX 7 from safety standards related to an anti-ice system in order to put it into service, and it recently told airlines to check their 737 MAX aircraft for a loose bolt in the rudder system.
• Aircraft makers occasionally find problems and suggest fixes as a matter of course — but in combination with Friday's episode and the earlier MAX 8 debacle, these data points start to paint a picture of a troubled program.

What they're saying: If Boeing winds up responsible for the issue, "then we're just putting another log on the fire that there needs to be increased focus on the engineering culture of the company," Bank of America analyst Ronald Epstein tells Axios' Hope King.

What's next: Investigators will need time to figure out exactly what went wrong on Alaska 1282.

• Their findings will both inform any necessary fixes, and likely show where any blame lies.

The bottom line: "If it ain't Boeing," the old saying went, "I ain't going."

• Now, though, that slogan feels like a relic of another time.