The Federal Aviation Administration announced that it would not approve Boeing production increases until the agency reviewed and approved the company’s safety improvement plan.

In February, the Federal Aviation Administration (FAA) ordered Boeing to formulate a plan within 90 days in the wake of a door plug that blew off a Boing 737 Max 8 aircraft shortly after takeoff, as previously reported by The Dallas Express. Scrutiny in the company amplified thereafter, with two whistleblowers who were in the process of providing information about issues with quality control dying under mysterious circumstances.

Boeing executives, including departing CEO Dave Calhoun, presented the safety improvement plan to FAA officials during a three-hour meeting on Thursday. According to FAA Administrator Mike Whitaker, the plan was broken into several components, from improvements to employee training and procedures to prevent suppliers from shipping defective components to the planemaker.

“This is a guide for a new way for Boeing to do business,” said Whitaker, adding that it was now up to the company to implement it, per CNN.

Developing the elaborate plan is only the first of many steps Boeing is expected to take before being permitted to increase its current production of highly demanded 737 Max planes.

Whitaker predicted that it could take months — and several FAA audits — before the monthly cap is lifted.

“We are confident in the plan that we have put forward and are committed to continuously improving,” said Stephanie Pope, chief executive of Boeing’s commercial airplane unit, as reported by CNBC. “We will work under the FAA’s oversight and uphold our responsibility to the flying public to continue delivering safe, high-quality airplanes.”

Boeing is making changes to avert various quality and safety issues that have come to light, including adding 300 employees, introducing workplace coaches, and reducing the number of meetings managers attend to allow more time on the production floor.

Processes, such as “traveled work,” in which assembly sequences are done out of order, will be banned after being linked to skipped inspections.

However, these changes will come at a significant cost, with approximately $4 billion being poured into improving safety and quality control, Boeing Chief Financial Officer Brian West said, per CNBC.

Even with the FAA refusing to increase the 737 MAX production cap, Boeing has been far from reaching its potential output. While the maximum rate is 38 planes per month, it has only built roughly 21 per month in the year’s first quarter.

Production slowdowns and delays have resulted in significant snarls in the airline industry. As covered in The Dallas Express, the absence of new Boeing aircraft has pushed American Airlines to cut three long-haul routes at Dallas-Fort Worth International Airport.