The Justice Department is reviewing whether an early January incident in which a part of a Boeing plane exploded mid-flight violated a 2021 agreement to resolve a criminal charge against the company, according to a person familiar with the review.

Boeing agreed to pay more than $2.5 billion to settle the charge, which arose from two fatal crashes of its 737 Max 8 planes. The deal, reached in the final weeks of the Trump administration, was criticized at the time for being too lenient on the company.

Under the terms, Boeing agreed to compensate the families of the crash victims, as well as the airlines affected by the grounding of the planes. The Justice Department agreed to drop a criminal charge based on the actions of two employees who had withheld information from the FAA.

Last month, a panel in the fuselage of a larger Max 9 exploded at an altitude of 16,000 feet shortly after takeoff from Portland, Oregon, exposing passengers to deafening wind. There were no serious injuries, but the incident could have been catastrophic if it had occurred minutes later, at a higher altitude. The panel is known as a “door stopper,” and is used to cover a gap left by an unnecessary exit door.

The Justice Department review was reported previously by Bloomberg.

The January episode reignited the intense scrutiny and criticism that Boeing faced after crashes in Indonesia in late 2018 and in Ethiopia in early 2019 killed a total of 346 people. The Max 8 and Max 9 were banned from flying globally days after the second crash. Since the planes began flying again at the end of 2020, they have made several million flights around the world.

The weight of the crisis seemed to be lifting before the January incident. A preliminary report from the National Transportation Safety Board suggested that the plane in that episode may have left the Boeing factory without the bolts needed to secure the panel. The Federal Aviation Administration immediately grounded nearly 200 Max 9 planes in the United States pending inspections. Flights on the plane have since resumed.

The FAA also increased inspections of the Washington state factory where Boeing makes the Max. On Wednesday, the agency gave the company 90 days to come up with a plan to improve quality control.

“Boeing must commit to making real, deep improvements,” FAA Administrator Mike Whitaker said in a statement announcing the deadline. “Achieving fundamental change will require sustained effort from Boeing leadership, and we will hold them accountable every step of the way, with mutually understood milestones and expectations.”

Earlier this week, an FAA expert group released a long-awaited report stemming from the Max crashes and found that Boeing’s safety culture was still poor, despite improvements in recent years.