The investigation of the accident of the Boeing 737 Max 9 of Alaska Airlinesthat the January 5, 2024 had been forced to a Emergency landing In Portland, in Oregon, after one of the lateral hatches had suddenly detached himself: it was a cause to cause the accident human error of Boeing employees, who at the end of a intervention on the structure of the plane they did not reinsert 4 panel boltsessential to prevent the movement of the left side exit cap.
The first inspections of the Alaska Airlines and United Airlines airlines had already found some Loose bolts in the fuselage panels, but after an investigation lasting 17 months The official confirmation from the National Transportation Safety Board (NTSB)the US investigative agency that dealt with the case and which has noted different systemic failures at the level of managing the maintenance and safety of the aircraft. From the investigations, among other things, it also emerged that only one bolt It would have been enough to avoid the detachment of the cap from the side door.
In its conclusions, the investigative agency criticized the Federal Aviation Administration (FAA) for having Safety problems underestimatedaccused of not having supervised enough on Boeing quality standards. The aircraft manufacturer was instead recommended to improve the training program of its employees, strengthening the protocols for risk management during maintenance work.
The causes according to the NTSB report: the errors that led to the accident
17 months after the accident of Flight 1282 of Alaska Airlinesthe NTSB therefore concluded the investigation by attributing the causes of the event to a human error: specifically, the Boeing 737-9 plane has undergone the detachment of the “Left door cap central output “(ie the Med panel) while it was at a height of 14,830 feet (about 4,500 meters).
This detachment was caused by the absence of 4 boltswho should have set the left -hand cap, to prevent it from moving vertically upwardsand that they were already missing before the aircraft was delivered to the Alaska Airlines airline. Consequently, the Media Eta cap capable of gradually moving upwards during all previous tripsuntil, during flight 1282, he moved to disengage from the arrest fittings and completely separate from the aircraft.
However, the NTSB stressed that the upward movement of the cap could not have been detected during a simple pre-earlier inspection. Consequently, it has been established that, during the construction of the aircraft by Boeing, the personnel opened the left -hand cap, removing the 4 bolts and associated hardware, without however following the safety procedures adequate and in the absence of qualified personnel. According to experts, of the 24 technicians available, only one owned the necessary skills To carry out the intervention correctly, but at that moment it was not present.
The investigation also confirmed that only one bolt It would have been enough to avoid the detachment of the tailgate in flight.
Among other things, the activity of the maintenance team should have been included in the so -called “Removal Record», A document used for record all interventions carried out on the aircraft, just to verify that all quality guarantees are actually respected. In this case, however, the register was not produced: because of this forgetfulness, therefore, they were not performed inspections adequate on the closure of the cap, which could have identified the absence of the 4 bolts before the accident.
In its conclusions, the US investigative agency has finally contested one poor surveillance by the Federal Aviation Administration (FAA), which deals with regulating the entire civil aviation sector in the United States. In particular, FAA surveillance and control activities have been defined ineffectivehaving not managed to guarantee the respect of the safety measures by Boeing, which was not sufficiently supervised during the processes of removing or alteration of the parts of a aircraft.
Boeing and FAA recommendations for security checks
At the end of the investigation, the investigative agency formulated a series of recommendations towards Boeing and Faa: the aircraft manufacturer was suggested to improve the training program of its employees, defining specific guidelines to be applied both during maintenance procedures and in production processes.
At the Federal Aviation Administrationon the other hand, was recommended to convene a group of Independent experts to conduct a complete review of Boeing security procedures.
