DOJ has reportedly subpoenaed Boeing as part of a criminal investigation involving the 737 Max

The US Department of Justice (DOJ) has subpoenaed Boeing as part of a criminal investigation into the certification and marketing processes for the aerospace manufacturer's 737 Max aircraft, CNN reported.The investigation reportedly concerns the process Boeing used to determine its 737 Max aircraft were safe for flight and the data it gave to the Federal Aviation Administration about that process.Investigators have asked for information from Boeing about the company's pilot-training manuals and marketing for the 737 Max aircraft, according to the CNN report.The DOJ, the FBI, and Boeing did not immediately respond to Business Insider's requests for comment.The US Department of Justice (DOJ) has subpoenaed Boeing as part of a criminal investigation into the certification and marketing processes for the aerospace manufacturer's 737 Max aircraft, CNN reported.The investigation reportedly concerns the process Boeing used to determine its 737 Max aircraft were safe for flight and the data it gave to the Federal Aviation Administration about that process. Investigators have asked for information from Boeing about the company's pilot-training manuals and marketing for the 737 Max aircraft, according to the CNN report.Read more: The Ethiopian Airlines and Lion Air crashes show eerie similarities — here are all the things they have in commonThe investigation reportedly began after the October 2018 crash of a Lion Air flight involving a 737 Max 8 aircraft. The Federal Bureau of Investigation's (FBI) Seattle division and the DOJ's criminal division are running the investigation, according to CNN.The DOJ, the FBI, and Boeing did not immediately respond to Business Insider's requests for comment.Boeing's 737 Max aircraft, which entered service in 2014, have come under scrutiny after the Lion Air crash and a March crash of an Ethiopian Airlines flight, which also involved a 737 Max 8. Both crashes killed all passengers and crew onboard.Many countries, including the US, China, France, and Britain, have grounded the 737 Max 8 as investigators work to determine what caused each crash. While investigators have not released their final reports, there appear to be a number of similarities between the crashes, including the possible involvement of the 737 Max's Maneuvering Characteristics Augmentation System (MCAS), which points an aircraft's nose downward if the plane is flying at too steep an incline.Boeing installed the system on 737 Max aircraft because they feature larger engines that had to be mounted in a different way from those on prior 737 aircraft. The new engines created a tendency for 737 Max aircraft to tilt upward, which makes it more likely that they will stall in midair. The MCAS was designed to counter this tendency.Evidence from both incidents indicates that the pilots on each flight struggled against the MCAS before their planes crashed, and speculation from observers has suggested that the sensor that causes the MCAS to point the plane downward may have activated in each case due to an error.Two days after the Ethiopian Airlines crash, Boeing said it would release a software update for its 737 Max fleet.If you've worked for Boeing and have a story to share, contact this reporter at mmatousek@businessinsider.com.Read more:Europe and Canada are investigating the Boeing 737 Max themselves rather than trusting the US — another apparent snub of American regulatorsThe crashed Lion Air and Ethiopian jets lacked safety features that could have helped because Boeing charged extra for them, report saysThe crashed Lion Air 737 Max had the same malfunction the day before, but crew figured out how to stop it. The information never made it to the next flightA cockpit voice recording from doomed Lion Air 737 Max shows pilots scoured the plane's manual to fix its fatal dive but couldn't find the right procedure in time