Showers of jet engine parts over residential areas on both sides of the Atlantic have caught regulators’ attention and prompted the suspension of some older Boeing Co planes from service.
Saturday’s incidents involving a United Airlines 777 in Denver and a Longtail Aviation 747 freighter in the Netherlands put engine maker Pratt & Whitney in the spotlight, though there is no evidence they are related.
Pratt & Whitney, which is owned by Raytheon Technologies Corp, said it was coordinating with regulators to review inspection protocols. It is expected to increase inspections ordered after previous incidents.
After the Colorado engine failure, when United Flight 328 dropped debris on a northern Denver suburb before landing safely, Boeing recommended the suspension of 777s with the same variant of PW4000 turbine. Japan, meanwhile, imposed a mandatory suspension.
The European Union Aviation Safety Agency (EASA) weighed in on Monday, requesting more information on the Pratt engines in light of both events. A woman sustained minor injuries in the Dutch incident, which scattered turbine blades on the town of Meerssen. One was found embedded in a car roof.
After receiving more information, EASA said the incidents were unrelated. “Nothing in the failure and root analysis show any similarity (between the two incidents) at this stage,” the regulator said.
The U.S. Federal Aviation Administration (FAA) said it would soon issue an emergency airworthiness directive based on the United event.
Both incidents involve the same type of PW4000 engine that equips a relatively small number of older planes, some grounded by the COVID-19 pandemic, limiting the likely repercussions.
They nonetheless bring a new headache for Boeing as it recovers from the much more serious 737-MAX crisis, which resulted in the grounding of its flagship narrowbody jet after two deadly crashes.
“This is certainly an unwelcome situation for both Boeing and Pratt, but from time to time issues will pop up with aircraft and engines,” said Greg Waldron, a managing editor at industry publication Flight Global.
“The PW4000-powered 777-200 is slowly fading from service,” he said, adding that the pandemic-driven slump means that airlines forced to suspend it “should be able to fill any network gaps” with 787s or other 777s equipped with General Electric Co engines.
Analysts at broker Cowen predicted limited impact on Boeing’s share price, which fell about 2.1% on Monday.
The 777-200s and 777-300s affected are older, less fuel-efficient models still flown by five airlines: United, Japan Airlines, ANA Holdings Inc, Asiana Airlines Inc and Korean Air. Most are in the process of being phased out.
Boeing said 69 of the 777s operating globally with PW4000s had been in recent service, with another 59 stored. Pratt & Whitney engines power less than 10% of the delivered 777 fleet of more than 1,600 planes.
United suspended 24 of its 777s, pre-empting Boeing’s advice, after the Saturday blowout that dropped the right engine’s protective outer casing near homes.
A large majority of 777s in service today are powered by engines made by General Electric, the sole supplier on recent models.
In the Dutch case, the Longtail pilot was informed of an engine fire by air traffic control after taking off from Maastricht, bound for New York, and diverted to Liege, Belgium.
The Dutch Safety Board on Monday said it was investigating the incident.
Examination of the 26-year-old United jet showed damage was mostly confined to the right engine, the U.S. National Transportation Safety Board (NTSB) said. Its inlet and casing came off and two fan blades were fractured, with others showing damage.
The FAA said early findings suggested that the “inspection interval should be stepped up for the hollow fan blades that are unique to this model of engine, used solely on Boeing 777 airplanes.”
The cause of the engine fire in the Netherlands incident remained unclear.
In-flight PW4000 engine failures have previously been examined by authorities.
Another United 777 of the same vintage suffered an engine failure in February 2018, when a cowling fell off about 30 minutes before the plane landed safely. A full-length fan blade fracture was behind the incident, the NTSB determined.
After a malfunction forced a Tokyo-bound JAL 777 to return abruptly to Naha airport in December, Japan’s Transport Safety Board reported it found two damaged fan blades, one with a metal fatigue crack. Its investigation is ongoing.
JAL, which operates 13 of the planes, said they were scheduled for retirement by March 2022.
The smaller PW4000 engines on some Boeing 747s and 767s, as well as some Airbus A330s, do not feature the hollow titanium fan blade suspected of being involved in the United 777 incident.
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