In a statement Sunday evening, FAA Administrator Steve Dickson said initial data indicated the need for more frequent maintenance of the Boeing 777 airplanes equipped with a type of engine called a Pratt & Whitney PW4000. Investigators appear to be focused on a potential malfunction of a part that is unique to these engines called a hollow fan blade.
The FAA said United is the only U.S. air carrier with this type of engine in its fleet. The regulator said Japan and South Korea are the only other countries with airlines that operate planes with the affected engines.
The National Transportation Safety Board said Saturday it was investigating the causes of the engine failure incident, which local authorities said badly damaged at least one home and one vehicle.
United Airlines, which operated the flight, said it is temporarily and voluntarily removing the planes from its fleet “out of an abundance of caution” and is working with investigators to determine any additional precautions.
“As we swap out aircraft, we expect only a small number of customers to be inconvenienced,” United spokesman David Gonzalez said in an emailed statement.
In an emailed statement, Boeing spokesman Bradley Akubuiro said the company is cooperating with investigators.
The plane’s engine was manufactured by Pratt & Whitney, a subsidiary of Raytheon, a spokesman for the NTSB confirmed. Pratt & Whitney did not respond to a request for comment.
Residents of Broomfield, a suburb of Denver, reported hearing a loud boom overhead, and a video posted to social media appeared to show the plane flying with its engine on fire. Authorities have not shared any details on possible causes of the failure.
The incident comes amid Boeing’s effort to restore public confidence in its planes. In December, Boeing’s 737 Max jets flew their first commercial flights for the first time since two crashes of the planes in 2018 and 2019 killed 346 people.
The Max crashes eroded the flying public’s trust in Boeing, one of only two major companies that dominate commercial airplane production. Following the incidents, Boeing halted production of its flagship jet, fired its chief executive and agreed to pay more than $2.5 billion to resolve a criminal charge by the Justice Department that it conspired to defraud the Federal Aviation Administration during a review of the 737 Max.
The Boeing 777-200 is a larger jet that has been in use since the 1990s. According to Boeing data, the jets have experienced less than one major accident per one million departures — one of the lowest accident rates of any major commercial jetliner. The plane is not equipped with MCAS, the software that investigators believe malfunctioned during both of the 737 Max incidents.
The FAA said South Korea and Japan are the only other countries with airlines operating planes with the affected engines. It said the Japan Civil Aviation Bureau has directed airlines to cease flying these planes.
The NTSB typically coordinates accident investigations with the help of the plane manufacturer, local authorities, the airline and any parts manufacturers that may have information relevant to a safety incident. The agency began retrieving scattered debris and collecting it in an airplane hangar at Denver International Airport over the weekend.
In Broomfield, local authorities fielded hundreds of calls from residents who found pieces of debris, said Rachel Welte, the public information officer for the Broomfield Police Department. One plane part fell through the roof of a home, and another badly damaged a truck, she said.
Debris was discovered all over Commons Park, a large recreational area with soccer fields, she said. “Considering how large the debris field was, it’s absolutely remarkable” that no one was injured, Welte said.