WASHINGTON • Boeing has called for the grounding of 128 of its B-777 planes across the world as United States regulators investigated a United Airlines (UA) flight where an engine caught fire and fell apart over a suburban American community.
UA, South Korea's Asiana and Japan's two main carriers - Japan Airlines (JAL) and All Nippon Airways (ANA) - confirmed they had already suspended operations of 63 planes fitted with the same family of engines which scattered debris over Denver on Saturday.
The National Transportation Safety Board (NTSB) in the US is probing the incident, in which no one was hurt.
Boeing warned that similarly fitted planes should be taken out of service until the Federal Aviation Administration (FAA) in America had determined an inspection procedure.
"While the NTSB investigation is ongoing, we recommended suspending operations of the 69 in-service and 59 in-storage 777 aircraft powered by Pratt & Whitney 4000-112 engines," Boeing said.
The announcements came after a UA B-777 aircraft landed safely at Denver International Airport last Saturday after its right engine failed.
The incident on Flight 328 from Denver to Honolulu took place shortly after the plane took off with 231 passengers and 10 crew members.
UA said the next day it would voluntarily and temporarily remove its 24 active planes, hours before Boeing's announcement.
The B777-200s and B777-300s affected are older and less fuel-efficient than newer models and most operators are phasing them out.
Images posted by police in Colorado showed significant plane debris on the ground, including an engine cowling scattered outside a home.
The NTSB said initial examination of the plane indicated that most of the damage was confined to the right engine, with only minor damage to the aircraft.
It added that the inlet and casing separated from the engine and two fan blades were fractured, while the remainder of the fan blades exhibited damage.
Japan's Transport Ministry ordered JAL and ANA Holdings to suspend the use of B-777s with PW4000 engines while it considered whether to take additional measures.
Tokyo said ANA operated 19 of the type and JAL 13, though the airlines said their use had been reduced during the pandemic.
On Dec 4 last year, a JAL flight from Naha Airport in Okinawa to Tokyo International Airport returned to the airport due to a malfunction in the left engine about 100km north of Naha Airport.
That plane was the same age as the 26-year-old UA jet involved in the latest incident.
Asiana, South Korea's second-largest carrier, said it would not fly any of its seven currently operational B-777s.
"We are still waiting for instructions from South Korea's Transport Ministry on inspections but we are taking pre-emptive measures by gradually switching aircraft," a spokesman said.
Flag carrier Korean Air added it was awaiting a directive from regulators "and will follow the directions once confirmed".
It said it had 16 of the planes, with 10 of them stored, and it would consult the manufacturer and regulators and stop flying them to Japan for now.
A spokesman for South Korea's Transport Ministry said it was monitoring the situation but had not yet taken any action.
UA is the only American operator of the planes, according to the FAA.
"We reviewed all available safety data," it added. "Based on the initial information, we concluded 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 planes."
In February 2018, a B-777 of the same age that was operated by UA and bound for Honolulu suffered an engine failure when a cowling fell off about 30 minutes before the plane landed safely.
The NTSB determined that that incident was the result of a full-length fan blade fracture.
Because of that 2018 incident, Pratt & Whitney reviewed inspection records for all previously inspected PW4000 fan blades.
The FAA in March 2019 issued a directive requiring initial and recurring inspections of the fan blades on the PW4000 engines.
Pratt & Whitney said it was coordinating with operators and regulators to support a revised inspection interval for the engines.
AGENCE FRANCE-PRESSE, REUTERS, BLOOMBERG