(NewsNation) — The Federal Aviation Administration announced it is conducting an investigation into Boeing after an incident where a door plug blew off an Alaska Airlines plane, causing a sudden depressurization.

The FAA notified Boeing it would be investigating to see if the manufacturer failed to comply with regulations meant to ensure products were made in accordance with approved designs and kept in suitable condition for safe flying.

The agency said the incident never should have happened and that Boeing needs to “comply with the high safety standards they are legally accountable to meet.”

Boeing CEO Dave Calhoun said the company will cooperate fully and prove their planes are safe to fly.

“We will cooperate fully and transparently with the FAA and the NTSB on their investigations,” he said.

An Alaska Airlines flight experienced sudden decompression shortly after take-off when a door pug on a Boeing 737 Max 9 blew off. The door plug is a panel that replaces a spot on the fuselage where an emergency exit door would normally be located.

Several passengers were injured during the incident, but the seats directly next to the plug were empty and there were no fatalities. The flight was safely rerouted back to Portland.

The FAA grounded Boeing 737 Max 9 models using the door plug after the incident and airlines using the planes reported finding loose bolts during inspections.

The National Transportation Safety Board is investigating the incident, noting that the bolts have not been found, though the door plug itself was located in a Portland-area backyard. The NTSB is also investigating three instances where a warning light went off on the plane prior to the door plug event.

Calhoun said the company acknowledges its mistakes after the accident.

Boeing has experienced a number of safety issues in recent years. In 2018, a woman was killed after a piece of engine housing came loose and shattered the window next to her seat on a Southwest Airlines 737.

Also in 2018, Boeing grounded its 737 Max 8 planes after two crashes in Indonesia and Ethiopia. The company’s Max planes have also experienced safety issues with loose bolts, problems with an anti-ice system and issues with fittings that connect the fuselage to the tail.

Some of those issues were directly connected to subcontractor Spirit AeroSystems, which Boeing said used a “non-standard manufacturing process.” Spirit AeroSystems was also responsible for installing the door plugs on 737 Max 9s.