The U.S. Federal Aviation Administration (FAA) will begin auditing Boeing’s plane production and step up oversight of the troubled maker after a door was ejected from a mid-flight airliner this week last, the latest in a series of accidents for its branded plane.

The agency’s decision comes just a day after it announced an investigation into whether Boeing failed to ensure the fuselage panel was safe and manufactured according to the design approved by regulators.

The FAA announced Friday that it will audit Boeing’s 737 Max 9 jetliner production line, as well as the company’s parts suppliers, “to assess Boeing’s compliance with its approved quality procedures “.

The FAA statement said it will also review the safety risks of delegating inspection authority to company employees and consider contracting out these functions to an independent third party.

“It is time to reexamine the delegation of authority and evaluate the associated safety risks,” FAA Administrator Mike Whitaker argued in the statement. “The grounding of the 737-9 and multiple production-related issues identified in recent years require us to examine all options to reduce risk,” said Mr. Whitaker, who was confirmed by the Senate as the new head of the FAA in October.

The agency will also increase monitoring of 737-Max incidents that occur while the plane is in service.

Boeing said Thursday it would cooperate with the FAA investigation, which focuses on plugs used to fill slots for additional exits when those doors are not required on airliners.

One of two caps on an Alaska Airlines jetliner exploded shortly after the plane took off from Portland, Oregon, a week ago, leaving a hole in the plane. The cabin lost pressure and the plane was forced to return to Portland to make an emergency landing. No serious injuries were reported.

After the incident, the FAA grounded all Max 9s equipped with these caps, forcing Alaska and United to halt flights. The plane remains grounded while the Transportation Safety Board (NTSB) and the FAA continue their investigation.