United Airlines’ Pratt & Whitney powered Boeing 777-200s remain grounded over six months following an uncontained engine failure over Denver, Colorado. Sources say regulators are looking to request additional safeguards, which could mean the planes will not fly again until next year.
Fan blade fatigue
As anyone with a keen interest in aviation will recall, in February this year, a United Airlines Boeing 777 had to return for an emergency landing shortly after taking off from Denver, Colorado, towards Honolulu, Hawaii. A 26-year-old 777-200 registered as N772UA was operating Flight UA328 when the plane’s number two engine suffered an uncontained failure.
Debris fell into a residential area below, and footage soon emerged of parts of the engine cowling lodged into someone’s front lawn. Thankfully, no one was injured on the ground during the event. The plane also landed safely back in Denver with no harm to passengers or crew.
The engine failure on UA328 was caused by the metal fatigue of a fan blade. This occurred despite the engine having gone through testing with thermal acoustic imaging (TAI) just under only 3,000 cycles prior.
In turn, this led to several national aviation authorities grounding Boeing 777s with the same engine type – Pratt & Whitney PW4077. The UK has since repealed a ban on the type. However, as the Wall Street Journal reports, United’s 54 grounded 777-200s could potentially not fly again until next year.
Additional safeguards and strengthening
People familiar with the matter told WSJ that US air safety regulators are considering an additional type of fan blade inspection. Furthermore, the FAA has requested modifications from Boeing aimed at preventing engine cowlings from being torn off in the event of a fan blade breaking in-flight.
The FAA declined to comment officially on what additional safeguard requests it would be making before allowing the aircraft to return to service. However, sources said the Administration could make a decision within the next few weeks. Meanwhile, a spokesperson for Boeing said the planemaker is completing design changes that will require FAA approval.
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Stored at long-term facilities
United said in April it was hoping to bring its PW4000 engined 777-200s back into service sometime ‘in the near future’. The sizeable fleet of 54 aircraft is parked at long-term storage facilities. These include Victorville in California and Roswell in New Mexico. However, a couple are hanging out at SFO.
Another two are in Asia – one in Hong Kong, and another in Xiamen, mainland China. The aircraft involved in the incident was also recently shipped off to the Mojave desert for storage after spending nearly six months in Colorado.
The loss of these key jets has is causing disruptions to United’s current operations. Their grounding may not have generated too many headaches in February as the carrier only had two dozen in active service at the time. However, US air travel has picked back up, and the airline is still left with a quarter of its widebody fleet on the ground, limiting capacity to Hawaii and hubs, as well as for cargo-only flights.