According to the NTSB, investigators took the door plug device of Flight 1282 on the lawn in the suburbs of Portland. The devices will then be sent to the NTSB Materials Laboratory in Washington, D.C., for examination.
This stopper was crucial to the NTSB's investigation, as it provided an accurate picture of how the fuselage disconnected from the aircraft a few minutes after takeoff.
The NTSB now has a lot of work to do, including examining the material under the microscope, interviewing more witnesses, and examining the records. The Cockpit Recorder (CVR) did not record any evidence, and the recording was overwritten after 2 hours without outside intervention.
The Federal Aviation Administration (FAA) grounded 171 aircraft of the same type after the 737 Max 9 (N704AL) Door Plug of Alaska Flight 1282 was blown up. The FAA said in a statement that airlines must complete enhanced inspections, including left and right door plugs, door components and fasteners. Operators must also complete corrective action requirements based on inspection results before any aircraft can be returned to service.
On January 9, United Airlines found that the bolts of several aircraft were loose during the preliminary investigation, which also highlights that the grounding was timely, otherwise, the same door plugs of these aircraft could blow up in the air at any time.
United said it sent a team of five technicians to work on each plane for a few hours. Now they also need to wait for the final approval of the full inspection process.
N704AL, delivered to Alaska Airlines on October 31, 2023, had three pressurization issues illuminated, most recently on Jan. 4, the day before the accident. Subsequently, Air Araski restricted the plane's flights over the water, such as banning flights to Hawaii.
Schematic diagram of the door plug design used on the Boeing 737-900 900ER, 737 MAX 8-200 and 737 MAX 9, it is unclear whether it is Boeing, Ace or the bolt manufacturer, although it is still necessary to wait for the final accident investigation, but Boeing needs to take responsibility, after all, the name "Boeing" is printed on the plane.
On the left side is the door plug, on the right side is the hatch. The door plug is closed, cannot be opened, and has no handle or pressure relief on the outside.
The door plug can be opened with the hinge facing down during maintenance.
Schematic diagram of the internal structure of the 737 Max 9 door plug fixed to the fuselage position.
Near the top of the door, there is a guide rail on each side and a roller pin on the door frame. When the door is closed, the ball pin enters the track. In order to open the door stopper, a downward force is required to press the door plug down against the lift assist spring until the ball pin leaves the guide.
The door plug is held in the closed position by four bolts, two of which go through the upper rail and two through the lower hinge bracket. Theoretically, these bolts prevent the door from moving vertically outward.
Locking bolts hold the roller pins in the rails.
In reality, this is the case.
On the bottom hinge there are two vertical motion stop bolts, which prevent the door from moving upwards.
Now the investigation is not only aimed at Boeing and Bound SharpIt also includes whether there are quality defects in the bolts or whether there are loopholes in the assembly process.
Prior to the accident, the N704AL had been in Oklahoma City for 10 days to install Wi-Fi at the base of its partner, AAR. The plane arrived in Oklahoma City on Nov. 27 and then returned to Seattle on Dec. 7 — the same day that the plane's warning lights were added.
Judging from the installation location information, the WiFi dome antenna and door plug installed by N704AL are very close. In a statement, the company said that the company "did not carry out any work on or near any mid-compartment exit door plugs for this particular aircraft." ”
An aviation expert said: "Installing a Wi-Fi dome may mean removing one or two panels near the top of the fuselage where the antennas and wiring are mounted. But don't pull the door plug off."
The Flight 1282 incident also spread to the capital market - Boeing's share price **8%, the largest drop in a year. And the 737 fuselage manufacturer is bound to be sharp, even more **11%.
The reputation of the Boeing 737 MAX has taken another blow when its chief executive, Dave Calhoun, announced the cancellation of the annual executive meeting scheduled for Monday and instead asked all employees to hold a cybersecurity meeting at the 737 Renton plant on Tuesday.
Boeing needs to rebuild public confidence after a series of manufacturing problems.