NEW YORK (AP) — Boeing told employees Monday that it plans to increase quality inspections of its 737 Max 9 aircraft, following the failure of an emergency exit door panel on an Alaska Airlines flight last week.

It is the latest in a series of troubles for Boeing, whose reputation as the premier American aircraft manufacturer has been tarnished by a series of manufacturing flaws that have led some airlines to hold off aircraft purchases or go with its European rival, Airbus.

The inspections come after Federal regulators grounded the 737 Max, and that Boeing has said that after the Alaska Airlines flight and customer complaints, it is “clear that we are not where we need to be” on quality assurance and controls.

“Our team is also taking a hard look at our quality practices in our factories and across our production system,” said Stan Deal, the president and CEO of Boeing Commercial Airplanes, in an email to employees.

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Boeing is also bringing in airline customers and independent inspectors to go over the aircraft as needed, Deal wrote.

One of two door plugs on an Alaska Max 9 blew out 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 descend rapidly and return to Portland for an emergency landing. No serious injuries were reported.

Following the incident, Federal Aviation Administration announced last week that it plans an investigation into whether the manufacturer failed to make sure a fuselage panel that blew off was safe and manufactured to meet the design that regulators approved.

The National Transportation Safety Board is focusing its investigation on plugs used to fill spots for extra doors when those exits are not required for safety reasons on Boeing 737 Max 9 jetliners.

The incident on the Alaska plane is the latest in a string of mishaps for Boeing that began in 2018, with the first of two crashes of Max 8 planes in Indonesia and Ethiopia — and more than four months apart — that killed a total of 346 people.

Max 8 and Max 9 planes were grounded worldwide for nearly two years after the second crash. Since then, various manufacturing flaws have at times held up deliveries of Max jets and a larger Boeing plane, the 787. Last month, the company asked airlines to inspect their Max jets for a loose bolt in the rudder-control system.