Missing bolts that secure the panel to the frame of the Boeing 737 Max 9 plane may have caused the door to detach on the Alaska Airlines plane last month, according to the group that is conducting investigations. The National Transportation Safety Board released a preliminary report on the Jan. 5 incident on Tuesday.
The report includes a photo from Boeing, which manufactured the panel, showing that three of the four bolts that prevent the panel from moving are missing. The location of the fourth bolt is not visible.
Investigators say the lack of damage around the panel indicates that all four bolts were missing before the plane took off from Portland, Oregon. The pilots were forced to make an emergency landing with a hole in the side of the plane. The lack of bolts caused the panel to detach from the airframe.
The preliminary report indicates that the device that closes the plane’s door, installed by the supply company “Spirit AeroSystems”, arrived at the Boeing factory near the city of Seattle with five parts damaged. The Boeing team replaced the damaged parts, a process which required the removal of the four bolts in question.
Safety experts have said that the accident could have had catastrophic consequences if the plane had reached the correct flight altitude. The depressurization in the aircraft after the panel was detached would have been high and the passengers and crew may not have been in seat belts.
Although the preliminary report pointed to Spirit’s role in the incident, Boeing CEO David Calhoun said last week that his company took responsibility.
“I want everyone to know that Boeing takes responsibility. We own our supply chain and the Spirit brand. We are responsible for the results of our work,” Mr. Calhoun told CNBC.
The incident has raised questions about the quality of production of Boeing aircraft.
The Federal Aviation Administration is investigating whether Boeing and its suppliers followed proper safety procedures in the production of parts for the Max plane. The US agency has banned Boeing from accelerating production of the 737 model until the agency is satisfied with the quality of production.