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Boeing on Feb. 21 said it recommends “suspending operations” of 777 aircraft powered by Pratt & Whitney 4000-112 engines, following an engine failure on a Boeing 777-200.
The incident occurred on Feb. 20 with United Airlines Flight 328. According to the National Transportation Safety Board’s (NTSB’s) ongoing investigation, the 777 aircraft — which was powered by the Pratt & Whitney PW4077 — experienced a right engine failure shortly after takeoff from Denver International Airport. The plane, which was heading to Honolulu, Hawaii, was able to safely return to Denver. Upon its return, the plane dropped engine debris over Denver neighborhoods. None of the 229 passengers or 10 crewmembers were injured.
The NTSB reported that after initial examination of the PW4077 engine, it was revealed that two fan blades were fractured, and the inlet and cowling separated from the engine. Specifically, “one fan blade was fractured near the root; an adjacent fan blade was fractured about mid-span; a portion of one blade was imbedded in the containment ring; and the remainder of the fan blades exhibited damage to the tips and leading edges,” the report reads.
While the NTSB’s findings are preliminary, some 777 planes will be removed from service, according to Federal Aviation Administrator Steve Dickson.
The FAA has issued an Emergency Airworthiness Directive that “would require . . . the inspection interval [to be] stepped-up for the hollow fan blades that are unique to [the PW4000 engines] used solely on Boeing 777 airplanes,” Dickson said.
There are currently 69 in-service and 59 in-storage Boeing 777s powered by the 4000-112 engines. Acting out of caution, United Airlines said it would immediately pull 24 Boeing 777 aircraft powered by PW4000 series engines from its schedule.
The Japan Civil Aviation Bureau has also issued a directive to temporarily suspend operations of 777s equipped with PW4000 engines. This affects 19 of All Nippon Airways’ 777 planes, and 13 operated by Japan Airlines.
The planes are also operated by Korean Air and Asiana Airlines; both airlines followed suit and voluntarily grounded their Boeing 777s following the incident.
While the specific 777 configuration is not operated by any U.K. airline, the U.K. Civil Aviation Authority is taking precautions, announcing on Feb. 22 that it will temporarily ban all Boeing 777s powered by the PW4000-112 engine from operating in U.K. airspace.
Boeing said in a statement that it is “working with these regulators as they take actions while these planes are on the ground and further inspections are conducted by Pratt & Whitney.”
Pratt & Whitney added that it is “actively coordinating with operators and regulators to support the revised inspection interval of the Pratt & Whitney PW4000 engines that power Boeing 777 aircraft.”
The FAA is currently working with Pratt & Whitney and Boeing to finalize details of the Airworthiness Directive. “Exact details of the inspection will be specified in the emergency order,” Dickson said.
The cockpit voice recorder and flight data recorder were transported to the NTSB laboratory in Washington where each will be downloaded and analyzed, according to the NTSB report.