After more than a year on the ground, United Airlines' sub-fleet of Boeing 777s powered by Pratt & Whitney PW4000 engines is set to make a comeback - if all goes according to plan, at least. The collection of 52 aircraft had been grounded in February 2021 after a dramatic engine failure in 2021 which saw parts of the engine land in neighborhoods outside the American city of Denver.

Return to service at the end of May

According to FlightGlobal, United Airlines is reporting that its 52 Boeing 777s powered by PW4000 powerplants will gradually resume service from May 26th. However, this re-introduction to service remains up in the air (unlike the aircraft in question).

That's because the final call will come from American civil aviation regulator, the Federal Aviation Administration (FAA), with an airline spokesperson telling FlightGlobal:

“We can and will return the 777 to service, but we are still working through that with the FAA, Boeing, and Pratt & Whitney...We are very respectful of the role that the FAA needs to play to…confirm independently that it is safe to return.”

And so, while the airline is anticipating a May 26th resumption, it will indeed be up to a rigorous assessment conducted by the FAA. "We continue to work closely with them on that," the airline spokesperson added.

The problem and solution

The cause of the United Airlines 777 engine failure which prompted the grounding, was the cracking of two fan blades as a result of metal fatigue. The breaking of these blades, moving at high speeds, caused the separation of the engine’s inlet and cowling from the powerplant.

To prevent similar situations in the future, the FAA has mandated the following as directives:

  • Operators are required to install debris shields on the thrust reverser inner wall. They will also need to inspect fan cowl doors for moisture ingression and have repetitive checks of the hydraulic pump shutoff valves.
  • A modification of the engine inlet to withstand possible fan blade failures.
  • Specific corrective actions, depending on inspection results.
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Parts of the engine had to be strengthened. Photo: NTSB

Domestic missions first

The aircraft and their gradual re-introduction will initially operate domestic missions. In a month's time, the airline hopes to have “a number [of aircraft] in the teens” operating international services, as well as flights from the continental US to Hawaii. After mid-June, if all goes well, the airline will continue to press forward with introducing more of the affected fleet back into service.

This service resumption couldn't come at a better time. Pent-up, post-pandemic travel demand combined with a busy summer travel season is sure to send demand soaring around the world but particularly in the United States. Hopefully, United will soon get the news that it's hoping for: A green light from the FAA to officially fly the jets again.

Will you be flying with United in the near future? Possibly on one of their 777s? Let us know by leaving a comment!

Source: FlightGlobal