Federal investigators slammed Boeing for ‘blatantly violating’ the rules by sharing unproven speculation about the 737 Max blowout

• The NTSB said Boeing "blatantly violated" rules about investigations.
• It said a Boeing exec made "unsubstantiated speculations" about the Alaska Airlines blowout .
• It will coordinate with the DoJ, which is considering criminal charges over the blowout.

Boeing has apologized after the National Transportation Safety Board said it "blatantly violated" rules about investigations.

On Tuesday, a Boeing executive held a media briefing about January's Alaska Airlines blowout. Sharing non-public information about investigations without the NTSB's consent is against the agency's rules.

The director of the NTSB's office of aviation safety sent a scathing letter to Boeing CEO Dave Calhoun on Thursday.

Timothy LeBaron said that since Boeing has been party to "several other investigations over the years," it is familiar with the investigative processes, "perhaps more so than most other entities."

In the letter, LeBaron said that Boeing Commercial Airplanes' senior vice president for quality, Elizabeth Lund, "made unsubstantiated speculations about possible causes" of the Alaska Airlines blowout.

"This disregard of federal regulations and rules governing NTSB investigations cannot be tolerated," he added.

The blowout sparked a crisis at Boeing, after a door plug came off a 737 Max in midair. Four bolts designed to hold it in place were never installed, the NTSB said in a preliminary report.

CNN reported that in the media briefing, Boeing blamed missing paperwork for the lapse in quality control.

LeBaron said that Lund shared "unsubstantiated speculations" and that "part of the released information was either inaccurate or unknown to the NTSB."

He also criticized Boeing for speaking about the investigation into a Southwest Airlines incident that occurred in May. The 737 Max experienced a Dutch roll, a rare but serious stability problem.

Boeing's chief engineer, Howard McKenzie, said the event had "nothing to do with design or manufacturing," according to LeBaron. However, LeBaron said that the NTSB hasn't ruled this out as contributing to the Dutch roll.

As a result of these statements, the NTSB said Boeing will no longer have access to its investigative information as it develops factual records.

The agency said it "will be coordinating with the DOJ Fraud Division to provide details about Boeing's recent unauthorized investigative information releases in the 737 Max 9 door plug investigation."

The Justice Department is considering whether to prosecute Boeing over the blowout.

In a statement shared with Business Insider, Boeing said: "As we continue to take responsibility and work transparently, we conducted an in-depth briefing on our Safety & Quality Plan and shared context on the lessons we have learned from the January 5 accident."

"We deeply regret that some of our comments, intended to make clear our responsibility in the accident and explain the actions we are taking, overstepped the NTSB's role as the source of investigative information," it added.

"We apologize to the NTSB and stand ready to answer any questions as the agency continues its investigation."