In a statement on Wednesday, Mike Whitaker, the F.A.A. administrator, said the agency was convinced that, with the necessary checks, the planes were safe.
“We grounded the Boeing 737-9 Max within hours of the incident over Portland and made clear this aircraft would not go back into service until it was safe,” he said.
But while existing planes could begin flying in a matter of days, the F.A.A. made it clear that Boeing’s troubles were far from over. In its statement, the agency said it would not allow Boeing to expand production of any of the 737 Max planes — not just the Max 9 but also other versions of the plane.
“Let me be clear: This won’t be back to business as usual for Boeing,” Mr. Whitaker said in the statement. He said the agency would not approve production increases until it was “satisfied that the quality-control issues uncovered during this process are resolved.”
The F.A.A. order is the latest in a series of problems for Boeing, and the 737 Max in particular. The line of fuel-efficient planes was meant to help the company regain ground it had lost to its European competitor, Airbus, and it quickly became the best-selling jet in Boeing’s history. But crashes of a different variant of the plane, the Max 8, in 2018 and 2019 killed 346 people and led to the Max’s being grounded worldwide.