Boeing and Pratt & Whitney seek FAA extensions for fixing troubled 777 engines

Boeing is responsible for redesigning parts of the nacelle and inlet areas of affected aircraft, while Pratt & Whitney oversees modifications to the engine itself. Boeing’s proposed solution includes updates to the engine core case fastening system and external hardware improvements aimed at reducing fire risks during fan blade separation events.

"If approved, this extension would provide operators more time to incorporate the updates into their fleet. In the interim, the fleet remains subject to a rigorous inspection programme," said Boeing in a statement.

The companies have faced technical challenges in meeting regulatory requirements for these design changes. Boeing initially outlined its proposals in 2021 after a major engine failure on Flight UA328 over Denver. Following this incident, as well as another similar event in February 2018 on Flight UA1175 over the Pacific Ocean, affected aircraft were grounded until temporary exemptions allowed them back into service in 2022.

At that time, regulators required that final design fixes be submitted by March 2027—one year ahead of implementation—and established a compliance deadline of March 2028. However, Boeing argues that ongoing technical obstacles and maintenance limitations make this timeline unworkable.

The Air Line Pilots Association (ALPA), representing pilots at several US airlines, has voiced concerns about extending deadlines further and urged both companies to speed up their work on permanent solutions. United Airlines supports Boeing's request for an extension due to what it describes as complex engineering challenges involved with these repairs.

In addition to United Airlines’ incidents with PW4000-powered jets, Japan Airlines also experienced a similar failure prior to UA328’s high-profile event; Japan Airlines subsequently grounded its own fleet for more than a year.

The PW4000 engine powers certain models of Boeing’s long-haul twinjets—including variants that can also be equipped with engines from General Electric or Rolls-Royce.