The chairman of the US National Transportation Safety Board (NTSB), Robert Sumwalt, said that, according to preliminary data, the agency considers metal fatigue in engine parts as the alleged cause of the accident in the US Denver, when a part of the skin fell off from the Boeing 777 liner.

According to the council chairman, two fan blades broke in the engine: one at the very base, the second broke about in the middle. Parts of the engine also slightly damaged the body of the aircraft. It is noted that the NTSB will continue to investigate, including trying to find out how long the fan blades were worn out.

“Speaking of a fan blade that broke at the base, a preliminary on-site inspection shows damage related to metal fatigue … As for the fan blade, which broke in the middle, its damage is related to the impact received when another blade, broken at the base, crashed into it,” Sumwalt said during a briefing.

He added that on Monday evening, the wreckage was sent to the laboratory of Pratt & Whitney, which is the manufacturer of the engine, where a second check is expected on Tuesday.