Boeing is being sanctioned by the National Transportation Safety Board after breaking an agreement by disclosing non-public details of the agency’s investigation into the Alaska Airlines mid-air door panel blowout. 

In a letter sent to Boeing CEO Dave Calhoun Thursday from Timothy LeBaron, director of the NTSB Office of Aviation Safety, LeBaron said that Elizabeth Lund, senior vice president of quality for Boeing, disclosed “non-public investigative information and made unsubstantiated speculations about possible causes” of the door blowout during a news conference Lund held Tuesday.

In a separate statement, the NTSB noted that both actions are prohibited according to an agreement that Boeing had signed that provided the aircraft maker with party status to the investigation.

“As a party to many NTSB investigations over the past decades, few entities know the rules better than Boeing,” the NTSB said in its statement. 

In his letter, LeBaron said that “given Boeing’s unauthorized release” of “investigative information,” the NTSB was “imposing restrictions on Boeing’s participation in the investigation.” 

The investigation relates to the January 5 incident when Alaska Airlines Flight 1282, which was carrying 174 passengers and six crew members on a Boeing 737 Max 9, suffered a mid-air blowout of a door panel just minutes after the flight left from Portland, Oregon.

In his letter, LeBaron said that “only appropriate NTBS personnel are authorized to publicly disclose investigative information and, even then, the disclosure is limited to factual information verified during the course of the investigation.”

LeBaron also said this second warning that the NTSB has issued to Boeing this year about a “flagrant violation” of NTSB rules. 

The agency said that Boeing will no longer have access to the investigative information it produces during its probe, and that the NTSB will also subpoena the company to appear at an investigative hearing from August 6-7 in Washington D.C. 

“Unlike the other parties in the hearing, Boeing will not be allowed to ask questions of other participants,” the NTSB said. 

Alaska Airlines also confirmed to CBS News in a statement Friday that it entered into a “purchase agreement” with Boeing to return the plane involved in the blowout to the aircraft manufacturing giant. Alaska Airlines also put in an order for a new 737 Max 10.

“They have taken possession of it and the registration has been changed. It is no longer part of our fleet,” the statement read.