Boeing 777 engine failure over Denver was caused by ‘metal fatigue,’ NTSB suggests

Photo (c) Richard Sharrocks - Getty Images

An investigation into the incident is ongoing

A preliminary investigation into the recent engine failure of a Boeing 777 has indicated that the damage was “consistent with metal fatigue.” 

In a statement, the National Transportation Safety Board (NTSB) said an initial examination of the Pratt & Whitney engine that failed just a few minutes into a United Airlines flight revealed: 

  • The inlet and cowling separated from the engine;

  • Two fan blades were fractured;

  • One fan blade was fractured near the root;

  • An adjacent fan blade was fractured about mid-span;

  • A portion of one blade was imbedded in the containment ring; and

  • The remainder of the fan blades showed damage to the tips and leading edges.

The PW4000 engine has 22 blades. Investigators said one of those blades was found lodged inside the plane’s containment ring, another landed in a soccer field in Colorado, and another broke free and hit another blade. 

What happened

On Saturday, a United Airlines flight heading from Colorado to Hawaii was forced to make an emergency landing after the engine failed. 

"The plane started shaking violently, and we lost altitude and we started going down," passenger David Delucia said, adding that he and his wife put their wallets in their pockets "in case we did go down, we could be ID'd".

In the wake of the incident, Boeing has recommended suspending the use of Boeing 777s powered by the Pratt & Whitney 4000 engine until the FAA establishes an inspection protocol. The FAA said Sunday that it would begin vigilantly investigating Boeing 777s with the engines in question. 

"We reviewed all available safety data following [Saturday's] incident," said FAA administrator Steve Dickson in a statement. "Based on the initial information, we concluded that the inspection interval should be stepped up for the hollow fan blades that are unique to this model of engine, used solely on Boeing 777 airplanes."

Pratt & Whitney said it’s “actively coordinating with operators and regulators to support the revised inspection interval” of the engines under investigation. "Any further investigative updates regarding this event will be at the discretion of the NTSB. Pratt & Whitney will continue to work to ensure the safe operation of the fleet."

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