Amid scrutiny, Boeing promises more quality checks. But is it enough?

After a door plug blew off an Alaska Airlines Boeing 737 Max 9 jet mid-flight, leaving a hole in the side of the plane and forcing an emergency landing, the airplane maker has been scrambling to restore confidence in the company's grounded aircrafts and get them back in the air.

Among other changes, the company is adding new quality inspections to 737 production lines at Boeing factories as well as Boeing's third party parts supplier, Spirit AeroSystems, according to a Monday statement. Spirit AeroSystems is the company that made the door plug involved in the incident on Jan. 5.

Boeing's Commercial Airplanes President and CEO Stan Deal also noted that airline customers, including Alaska and United Airlines, will be allowed to send their own inspectors to the factories, after both reported finding loose parts on their recently purchased 737 Max 9 planes.

"These checks will provide one more layer of scrutiny on top of the thousands of inspections performed today across each 737 airplane, and build on the reviews we have implemented to catch potential non-conformances," Deal said in a letter to employees.

He added: "While we complete these tasks to earn Federal Aviation Administration approval to unground the affected 737-9s, our team is also taking a hard look at our quality practices in our factories and across our production system."

The move comes amid sharp criticism from the Federal Aviation Administration, which has grounded 171 of the 737 Max 9 planes in the United States, as it conducts an audit of the Boeing's production line.

FAA officials have also said the regulator is considering adding an independent third-party inspector to oversee Boeing inspections and quality.

But the additional scrutiny — whether self-imposed or from the FAA — may not be enough to restore public faith in Boeing and the troubled 737 Max, which is now linked to the worst aviation disasters in recent history, said Rory Kennedy, the director of the documentary Downfall: The Case Against Boeing.

"Unfortunately, despite their their outward verbiage of assuring the public of how much they prioritize safety, what I'm seeing is evidence that they're continuing to lobby for shortcuts; for more efforts to not actually be held accountable for safety procedures," Kennedy told NPR.

Kennedy's film chronicles the events following two devastating Boeing 737 Max crashes in 2018 and 2019 that killed a total of 346 people, due in large part to the plane's flawed automated control system, called the Maneuvering Characteristics Augmentation System.

In the documentary, Kennedy shows how the company initially blamed the foreign plane pilots for the accidents, alleging they failed to follow procedures. Eventually, though, Boeing would turn over documents to Congress showing it knew about the control system problems all along and deliberately misled the FAA and the public about its safety.

Kennedy said that after getting over the initial shock over the Jan. 5 incident, she was not surprised because "Boeing has developed a culture that prioritizes finances and profits over human life."

In interviews with dozens of former employees, nearly all reported a major cultural shift within the company's executive ranks after the Boeing merger with McDonnell Douglas in 1997, Kennedy said.

The consensus from those who participated in the documentary is that Boeing's decades-long commitment to a safety-first approach to production was replaced by a focus on increasing shareholder value. That, they claimed, made it a speed-driven process where employees were allegedly discouraged from flagging problems, ultimately resulting in poorer quality aircraft.

"They got quality inspectors, quality managers, out of the picture," one former quality manager said, adding that the positions had been reduced from about 15 inspectors per building per shift, to one.

By the early 2000s, after several rounds of massive layoffs, Boeing's was tarnished by reports of employees leaving behind "foreign object debris" inside newly built planes — potentially catastrophic mistakes.

Those problems continued well into the next decade and even after the incidents in 2018, when Lion Air Flight 610 plunged into the ocean off the coast of Indonesia, and then less than five months later in 2019, when Ethiopian Airlines Flight 302 plummeted into the earth minutes after takeoff.

A year later, then-CEO Dennis Muilenburg was grilled by lawmakers in two days of intense congressional hearings. During his testimony he revealed that he knew about a series of 2016 messages between technical pilots in which they discussed "egregious" problems with the MCAS system. At the time, Muilenburg said, he didn't fully read the messages. Instead, he said he turned them over to company lawyers and only became familiar with their full content prior to the hearings.

In 2021, Boeing agreed to pay $2.5 billion to settle criminal charges, including a charge of criminal conspiracy to defraud the FAA.

And in 2022, after Boeing agreed to pay a $200 million penalty to settle Securities and Exchange Commission charges that the company misled investors and the public about the safety of the 737 Max, officials said Muilenburg "put profits over people by misleading investors ... in an effort to rehabilitate Boeing's image following two tragic accidents that resulted in the loss of 346 lives and incalculable grief to so many families."

Kennedy says the families of those killed in the crashes are now calling for a congressional investigation following the midair Alaska Airlines 737 Max 9 incident.

"We need to ask these larger questions about what's happening at the board level, what's happening with [CEO] David Calhoun, what's happening with these safety protocols," Kennedy said.

On Jan. 5, the same day of the door plug failure, The Seattle Times reported that in December, Boeing petitioned the FAA "for an exemption from key safety standards on the 737 MAX 7."

The request to the regulators came over the objections of the Allied Pilots Association, whose members are concerned about flying the plane due to problems with the jet's engine anti-ice system. The newspaper reports, "Boeing discovered a defect in the system with potentially catastrophic consequences."