The aircraft maker detailed its latest steps to correct lapses in quality in a memo to employees from Stan Deal, president of Boeing’s commercial plane division.

The memo went out after the Federal Aviation Administration finished a six-week review of the company’s manufacturing processes for the 737 Max jetliner after a panel blew off one of the planes during an Alaska Airlines flight on Jan. 5.

The FAA reviewed 89 aspects of production at Boeing’s plant in Renton, Washington, and found the company failed 33 of them, according to a person familiar with the report. The person spoke on condition of anonymity to discuss details that have not been publicly released – although they were reported earlier by The New York Times, which saw a slide presentation on the government’s audit.

“The vast majority” of violations found by the FAA involved workers not following Boeing’s approved procedures, Deal said in his memo.

Deal said the company will take remedial steps that include “working with each employee noted with a non-compliance during the audit to ensure they fully understand the work instructions and procedures.”

Boeing will also add weekly compliance checks for all work teams in the Renton factory, where Max jets are assembled, he said.

Deal acknowledged a recent conclusion by a panel of government and industry experts that found Boeing’s procedures for ensuring safety were too complicated and changed too often.

“Our teams are working to simplify and streamline our processes and address the panel’s recommendations,” he told staff.

The day before the blowout on Alaska Airlines flight 1282, engineers and technicians at the airline wanted to remove the plane from service to examine a warning light tied to the plane’s pressurization system, but the airline kept flying the plane and scheduled a maintenance check for late the following night, The New York Times reported Tuesday. Before that could happen, however, a door-plug panel blew off the jet 16,000 feet (4,800 meters) over Oregon.

Alaska told The Associated Press that the maintenance plan “was in line with all processes and procedures. Nothing required or suggested that the aircraft needed to be pulled from service.”

Bret Oestreich, president of the Aircraft Mechanics Fraternal Association, the union for technicians at Alaska, said there was nothing unusual in Alaska’s handling of the matter. He said the warning light does not indicate the location of a possible pressurization issue, and mechanics had been unable to pinpoint a problem after the light tripped on three earlier flights.

The earlier cabin-pressurization warnings caused Alaska to stop using the plane on flights to Hawaii. A few days after the blowout, National Transportation Safety Board Chair Jennifer Homendy said the warnings were unrelated to the accident. A preliminary report pointed to four bolts that were missing after a repair job at the Boeing factory.

Besides the ongoing FAA and NTSB probes, Boeing faces a Justice Department investigation into whether its recent problems — including the Jan. 5 blowout of an emergency door panel from an Alaska Airlines jet that had taken off from Portland, Oregon — violate terms of a settlement the company reached in 2021 to avoid criminal prosecution after two crashes of Max jets in 2018 in Indonesia and 2019 in Ethiopia killed 346 people.

Separately on Tuesday, Boeing reported that it received orders for 15 jetliners in February and delivered 27 planes, including two Max jets each to Southwest Airlines and United Airlines. TD Cowen analyst Cai von Rumohr called the deliveries “anemic” but not surprising because of increased FAA scrutiny of the company.

The slowdown in deliveries is putting Boeing farther behind European rival Airbus, which delivered 49 planes last month, and becoming increasingly frustrating for airlines.

Southwest said it might have to reduce its growth, as it now expects to receive fewer Max jets than it planned because of Boeing’s struggles.

Shares of Arlington, Virginia-based Boeing Co. closed Tuesday down more than 4%.