On Saturday, United Airlines Flight UA 328 from Denver to Honolulu with 241 passengers and crew suffered an uncontained engine failure of one of its two Pratt and Whitney PW4077 engines which caught fire and showered debris over a wide residential area. This appears to be identical to two other serious incidents involving a United Airlines 777 in February 2018 en route to Honolulu and a Japan Airlines 777 powered by the same engine type in December 2020 en route to Tokyo. In all cases, the 777s landed safely. United Airlines said in a tweet: "We are voluntarily & temporarily removing 24 Boeing 777 aircraft powered by Pratt & Whitney 4000 series engines from our schedule. We will continue to work closely with regulators to determine any additional steps and expect only a small number of customers to be inconvenienced." In a related development, the US regulator the FAA said that it is issuing an emergency airworthiness directive (AD) requiring immediate or stepped-up inspections for P&W-powered 777s.

FAA Administrator Steve Dickson said: “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.”

However, while P&W was one of the launch engine suppliers on the 777 in the early 1990s it no longer supplies engines for new 777s, with General Electric being the sole supplier. The most commonly used models of the 777 and the only ones in production are the 777-300ER and 777-200LR and 777F and all are powered by the GE90, the world's most powerful commercial jet engine. Airlines such as Emirates, Qatar, Singapore Airlines, British Airways, and Cathay Pacific Airways operate 777s powered by GE engines. The new 777X, which will enter service in 2023 is powered by the Ge9X engine from GE.