Boeing and P&W Seek FAA Extensions on 777 Engine Redesign

EAST HARTFORD– Pratt & Whitney (PW) and Boeing are asking the Federal Aviation Administration (FAA) for more time and regulatory exemptions tied to safety-driven redesigns of PW4000-112 turbofans used on Boeing 777s.

The move comes after multiple in-flight fan-blade failures involving PW4000-powered United Airlines (UA) 777s operating from airports including Denver (DEN), which led to severe engine damage, debris release, and in one case, fire.

Photo: Clément Alloing

Boeing and P&W Seek FAA Extensions

Pratt & Whitney filed a request on 25 August with the FAA seeking exemption from a fan-blade failure testing rule.

The company argues this approval would allow it to introduce PW4000-112 design improvements while ensuring the continued operation of Boeing 777 aircraft in the fleets of major U.S. carriers.

Although not named, United Airlines remains the only U.S. operator of PW4000-powered 777s, with 52 in service.

Both Boeing and Pratt & Whitney face a March 4, 2028, FAA deadline requiring that all PW4000-powered 777s be modified with approved design changes. This mandate does not apply to other 777s powered by GE Aerospace’s GE90 or Rolls-Royce Trent engines.

In May, Boeing requested an additional five years, which would push the compliance date to March 4, 2033, citing the complexity of the redesign and limited maintenance shop capacity for retrofits.

Photo: By John Murphy – Flickr, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=31532724

Joint Redesign Efforts

The two companies are pursuing a collaborative solution. Pratt & Whitney is responsible for hardware updates within the engine, while Boeing is redesigning inlet and nacelle structures to withstand fan-blade-out events.

These changes build on earlier temporary measures approved by the FAA in 2022, which allowed airlines to return grounded 777s to service after the 2021 United Airlines incident.

According to Boeing, the redesign includes updates to the engine core case fastening system to prevent flange separation and modifications to external hardware aimed at reducing the severity of engine fires.

Pratt & Whitney, an RTX subsidiary, emphasizes that the new design will maintain an equivalent level of safety despite the requested regulatory exemption.

Photo: NTSB Via Reuters

Safety Incidents That Triggered Action

Three serious fan-blade failures highlighted vulnerabilities in the PW4000-112 engines. The most notable occurred in February 2021 when United Airlines Flight 328, a 777-200, suffered a blade fracture shortly after takeoff from Denver (DEN).

The engine sustained major structural damage, ignited a fire, and scattered debris across a residential area.

Investigations by the National Transportation Safety Board (NTSB) found that the blade failure stemmed from metal fatigue. Similar PW4000-related failures were recorded in 2018 with another United Airlines 777-200 and in 2020 with a Japan Airlines (JL) 777-200.

Each event led regulators in the U.S., UK, and Japan to ground PW4000-powered 777s pending inspection and modification programs.

Photo: Cado Photo

FAA Oversight and Industry Response

The FAA initially gave Boeing until March 2027 to finalize design changes, with airlines required to comply by March 2028. However, Boeing and Pratt & Whitney now maintain that more time is necessary to identify a fully compliant integrated solution.

The Air Line Pilots Association (ALPA) has expressed concern about extending the timeline another five years, arguing that a permanent fix should be expedited. United Airlines, however, supports the extension, calling the current deadline unrealistic given the scale of required modifications.

FAA officials have acknowledged the complexity of the request and indicated that final decisions on exemptions may take longer than the standard 120-day review period.

Photo: Andrew Thomas | Flickr

What This Means for Airlines and Passengers

For now, PW4000-powered Boeing 777s remain in service under a rigorous inspection regime. Regulators, airlines, and manufacturers are aligned on the priority of safety, but the timeline for permanent design fixes remains in flux.

The outcome of these FAA exemption requests will determine whether operators like United Airlines can continue flying these widebody jets without disruption while the redesign process continues into the next decade.

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