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Regulator calls for stronger engine cowlings on B777s after United incident

written by Hannah Dowling | May 14, 2021

A United Boeing 777-200, registration N772UA, was performing flight UA328 to Honolulu on Saturday when it suffered an engine failure shortly after take-off from Denver (Image Source: NTSB)

The US Federal Aviation Administration has said it will soon mandate the strengthening of the engine cowling on Boeing 777s with Pratt & Whitney engines, following a United Airlines incident in February.

On 20 February, United Airlines flight UA328 suffered a “catastrophic and uncontained engine failure” on its right Pratt & Whitney PW4000 series engine shortly after take-off from Denver.

The failure resulted in debris from the engine cowling falling from the sky, while passengers stared at the fiery exposed engine. Powered by its one remaining engine, the aircraft landed safely back at Denver around 23 minutes after departure.

A very similar event occurred on a Japan Airlines Boeing 777 with the same PW4000 engines in December 2020.

As such, FAA Administrator Steve Dickson has now told a US House committee that the regulator would soon be drafting an airworthiness directive requiring affected Boeing 777 operators to “strengthen the cowling” – which covers the front of the plane’s engine – of their Pratt & Whitney engines.

Dickson also said it was actively working with both Boeing and Pratt & Whitney to ensure “the structure around the engine, the cowling and the inlet area, does not damage the aircraft structure” in the future.

The agency later said in a statement that it is unclear of the exact timing of when the airworthiness directive would be put in place, and said it “will depend on the completion of design and engineering work and will be approved by the FAA”.


In response to the news, Boeing said that it was continuing to work with the FAA on “potential design improvements” for the “inlet and fan cowlings” of the affected 777s.

The planemaker added that the work to address such problems is “exacting and time consuming”.

There are around 128 planes around the globe that would be affected by the upcoming airworthiness directive, with less than 10 per cent of the global fleet of Boeing 777s utilising he Pratt & Whitney PW4000-112 engine.

Currently, only United Airlines, Japan Airlines, ANA, Korean Air Lines, Asiana Airlines and Jin Air carry the affected 777s in their fleet.

Last month, United Airlines has announced it will return its 52 Boeing 777-200 aircraft with PW4000 engines to service, though was not clear on the timeframe for when it would do so.

United chief operations officer Jon Roitman announced the airline’s intentions in an earnings call with investors, and said, “We look forward to getting that aircraft back to safe operations in the future.”

Roitman said that the airline has had “really productive collaboration with Pratt Boeing and the FAA” over the investigation into the engine failure and fan blade testing.

Meanwhile, Japan Airlines opted to retire its fleet of 13 777s with the affected engines, rather than complete the costly process of sending parts to the US for inspection.


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