Airline regulators in the United States have initiated a formal investigation into Boeing's processes subsequent to the detonation of a door seal on one of its aircraft.

Boeing has been ordered by the Federal Aviation Administration (FAA) to investigate whether the company neglected to verify that the finished aircraft matched the approved design. For inspection purposes, the FAA had already suspended the majority of the 737 Max 9 fleet.

The post-emergency evaluations conducted on the Alaska Airlines flight have revealed deficiencies including loose bolts.

The FAA stated, that the incident should never have occurred, and it cannot occur again. It is imperative that Boeing's manufacturing operations adhere to the stringent safety standards for which the company is legally obligated.

Boeing stated that it would "fully and openly cooperate" with the investigation.

Dave Calhoun, the CEO of the company, had previously characterised the issue as a "quality escape." It indicates that the incident was the result of a quality control flaw in the aircraft, which had only been operational for eight weeks prior to the explosion.

In specific configurations, the door plug is a windowed fuselage component that occupies the location that an emergency egress would otherwise occupy.

The component detachment occurred shortly after the departure of a Boeing 737 Max 9 aircraft operated by Alaska Airlines on Friday from Portland, Oregon.

Although there were no significant casualties following an impromptu return to the airport, the FAA grounded 171 aircraft equipped with the identical door cover on Saturday.

The reinstatement date for the aircraft remains uncertain.

Despite the cancellation of hundreds of flights, Transportation Secretary Pete Buttigieg has stated that the government will not be hurried into clearing the grounded aircraft.

The aircraft, he mentioned must be 100 percent secure.

Alaska Airlines has cancelled approximately 20% of its flights due to the grounding of 65 Max 9 aircraft. United Airlines, the other main 737 MAX 9 operator in the United States, operates 79 of these aircraft.

It anticipated "significant" flight cancellations on Thursday, following the cancellation of 167 flights on Wednesday.

Alaska Airlines stated that it was still awaiting FAA approval of revised inspection and maintenance instructions from Boeing prior to resuming operations.

The airline stated, "We will not return these aircraft to service until all findings have been completely resolved and they meet all FAA and Alaska's stringent standards."

United and Alaska both reported discovering unsecured components on several of the grounded aircraft on Monday.

The detachable component was ultimately discovered in the backyard garden of a teacher, devoid of its four fasteners.

The chairman of the National Transportation Safety Board, Jennifer Homendy, stated on Monday that while the fasteners may have been absent from the beginning, they could have detach during the descent. The NTSB is conducting an investigation into the incident that occurred during the flight.

The incident has reignited scrutiny of Boeing, which has been attempting to repair its reputation since 346 people were killed in accidents in 2018 and 2019 involving a different model of the 737 Max.

Subsequently, its widely used 737 Max aircraft were suspended on a global scale for over 18 months. Since production has resumed, a series of minor issues have been reported.