February 22, local time, according to local media reports in the United States, Robert Samwater, chairman of the National Transportation Safety Committee, said on the same day that on the 20th
The fan blade of a United Airlines flight fell off, causing dozens of Boeing 777 aircraft around the world to be grounded.
Preliminary inspection shows that the cause of the accident is metal fatigue.
After the accident, investigators have already conducted a preliminary inspection of the fallen engine fan blades, Samwater said. The results of the investigation show that a crack that gradually widens over time eventually leads to a failure.
Investigators at the National Transportation Safety Board have begun reviewing repair records, interviewing crew members, and reviewing possible similarities with other failures, Samwater said.