Japan Airlines has decided not to return its 13 Pratt & Whitney PW4000-112-powered Boeing 777s to service following their suspension of operations due to recent in-flight engine failures, including a December 4 incident involving a JAL 777-200. The airline had planned to retire its Pratt-powered 777s by March of next year but has accelerated their removal in favor of service with Airbus A350-900s on domestic routes out of Osaka and shift other aircraft flying international service to maintain frequencies on flights within the country.
Japan grounded a total of 31 PW4000-112-powered 777s flown by JAL and All Nippon Airways on February 21, a day after a United Airlines 777-200's PW4000-112 failed soon after taking off from Denver on a flight to Honolulu. U.S. investigators found evidence of fan blade metal fatigue in the PW4000-112 engine that failed, raining nacelle debris over a mile-long area of a Denver suburb.
National Transportation Safety Board examinations found one blade fractured at the root, an adjacent blade fractured at about mid-span, and a portion of one embedded in the containment ring. The remainder of the blades showed damage to the tips and leading edges.
The NTSB continues to investigate the relationship between the latest PW4000 failure and previous events, such as a 2018 incident in which another of the engines in a United Airlines 777-200 suffered a fan blade failure on approach to Honolulu.
In the 2018 incident, investigators determined that a fractured fan blade caused the failure. Last year the NTSB determined that insufficient training for a thermal acoustic imaging (TAI) inspection process developed by Pratt & Whitney led to technicians misdiagnosing a problem with the fan blade that ultimately failed in the 2018 incident. Since then Pratt & Whitney developed a formal training curriculum for the inspections. The FAA issued an airworthiness directive in March 2019 requiring repetitive inspections of all PW4000s in service.
Meanwhile, Japanese investigators continue their probe into the case of a PW4000 failure that involved a Japan Airlines 777-200 flying from Naha Airport in Okinawa to Tokyo Narita Airport. That airplane also landed safely after returning to Naha Airport.
“We will continue to fully cooperate and respond to the investigation by the Japan Transport Safety Board to determine the cause of the incident,” said JAL in a statement.