NTSB Report Reveals Missing Bolts as Cause of Door Plug Blowout on Boeing 737 MAX 9
The National Transportation Safety Board (NTSB) has released a preliminary report on the recent door plug blowout incident involving a Boeing 737 MAX 9 jet. The report highlights a critical finding that four bolts crucial for securing the door plug were missing at the time of the incident.
The near disaster occurred during an Alaska Airlines flight (Flight 1282) from Oregon to California last month, with 177 passengers on board. In a 19-page report, the NTSB asserts that the investigation's focus has been squarely on the missing bolts. Further examination of the recovered door plug confirmed the absence of these bolts and provided key evidence for the ongoing inquiry.
The bolts in question are AN-6 bolts, a commonly used type of bolt in aviation. They play a crucial role in ensuring the stability and integrity of the door plug. Contrary to earlier speculation about the possible absence of a cotter pin, the NTSB's analysis definitively states that none of the bolts were present during the blowout.
Research conducted at the NTSB's Washington D.C. lab involved destructive testing of the recovered door plug. By analyzing the telltale signs on the door and its fittings, investigators confirmed that the bolts were not installed. It is theorized that these bolts were removed when the aircraft was relatively new, possibly during repairs to the fuselage.
Investigation records indicate that the fuselage, containing the door plug, was delivered to Boeing by a subcontractor on September 1, 2023. Boeing technicians at the facility detected issues with rivets adjacent to the door, prompting the removal of sections of the door and door plug. Photos taken during the September 19 maintenance work corroborate the NTSB's findings, showing the absence of the bolts.
This new revelation places further scrutiny on Boeing's quality control practices. The NTSB is now focused on determining why the bolts were removed and not reinstalled. Investigators are intent on understanding the specific instructions provided to Boeing workers at their Renton, Washington plant.
While the NTSB's preliminary report refrains from assigning blame to Boeing, the final report expected in approximately one year may provide more definitive conclusions. In response to the incident, the Federal Aviation Administration (FAA) has sent around two dozen inspectors to conduct an audit of Boeing's quality control procedures.
The alarming incident highlights the importance of robust quality control measures in aviation manufacturing. Despite the explosive nature of the blowout, the fortunate outcome of this incident is that no serious injuries were reported among the passengers and crew.
Further developments in the investigation will undoubtedly shed more light on the factors contributing to the missing bolts, raising important questions about the maintenance protocols and procedures implemented by Boeing. As the inquiry progresses, the aviation industry will eagerly await the final report, hoping to glean valuable insights that will bring about enhanced safety measures across the board.
