The move from the FAA comes as Boeing faces a growing chorus of criticism over its quality control processes.
The Federal Aviation Administration said on Wednesday it is halting any production expansion of the Boeing 737 Max, after a door plug suddenly fell off an Alaska Airlines jet.
“This won’t be back to business as usual for Boeing,” FAA chief Mike Whitaker said in a statement. “We will not agree to any request from Boeing for an expansion in production or approve additional production lines for the 737 MAX until we are satisfied that the quality control issues uncovered during this process are resolved.”
However, airlines that operate the Max 9 can begin the inspection process of existing aircraft. Once the inspections of each existing Max 9 are complete, they can return to service.
The federal agency had paused inspections of the Max 9, saying Boeing needed to revise instructions for maintenance after Alaska and United Airlines found some loose hardware in their initial inspections of the aircraft.
The Alaska incident has put Boeing under scrutiny over its quality control processes. As a result of the weeks-long grounding, United and Alaska have canceled hundreds of flights daily. United said in a filing on Monday that it was forecasting a first quarter loss due to the grounding.
United and Alaska CEOs also both expressed frustration and disappointment with the U.S. planemaker in televised interviews on Tuesday. United CEO Scott Kirby said the carrier was reconsidering its fleet plan to not include the Max 10, which has been hampered by regulatory and delivery delays, in a call with analysts on Tuesday.
Whitaker also said the FAA was stepping up its oversight of Boeing after the incident.
“The quality assurance issues we have seen are unacceptable,” Whitaker said. “That is why we will have more boots on the ground closely scrutinizing and monitoring production and manufacturing activities.”
As part of its increased oversight, the FAA said it would have a greater floor presence at Boeing facilities and launch an investigation on the planemaker’s compliance with manufacturing requirements.
Boeing is expected to report fourth quarter earnings on January 31.