U.S. regulators announced extra inspections on Boeing Co 777 jets using the same type of engine that shed debris over Denver on Saturday, while Japan went further and suspended their use while it considers what action to take.
The regulatory moves involving Pratt & Whitney 4000 engines came after a United Airlines 777 landed safely at Denver International Airport on Saturday after its right engine failed.
Japan's transport ministry ordered Japan Airlines Co Ltd (JAL) and ANA Holdings Inc to suspend the use of 777s with P&W4000 engines while it considered whether to take additional measures.
Japan said ANA operated 19 of the type and JAL operated 13 of them, though the airlines said their use had been reduced during the pandemic. JAL said its fleet was due for retirement by March 2022.
The ministry said on Dec 4, 2020, a JAL flight from Naha Airport to Tokyo International Airport returned to the airport due to a malfunction in the left engine about 100 kilometers north of Naha Airport on Okinawa.
That plane is the same age as the 26-year-old United Airlines plane involved in Saturday's incident.
United Airlines is the only U.S. operator of the planes, according to the Federal Aviation Administration (FAA). The other airlines using them are in Japan and South Korea, the U.S. agency said.
"We reviewed all available safety data following yesterday's incident," the FAA said in a statement. "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 airplanes."
The United 777 was powered by two Pratt & Whitney PW4000 engines. The plane, with 231 passengers and 10 crew on board, was heading to Honolulu when it suffered an engine failure soon after takeoff, the airline said.
There were no reports of injuries, either on the plane or the ground.
United Airlines said on Sunday it would voluntarily and temporarily remove its 24 active planes of the type from its schedule.
Images posted by police in Broomfield, Colorado showed significant plane debris on the ground, including an engine cowling scattered outside a home and what appeared to be other parts in a field. Police tape was used to cordon off the debris.
The National Transportation Safety Board (NTSB) said its initial examination of the plane indicated most of the damage was confined to the right engine, with only minor damage to the airplane.
It said the inlet and casing separated from the engine and two fan blades were fractured, while the remainder of the fan blades exhibited damage.
One video taken from what appeared to be inside the United plane showed an engine on fire.
Another video on social media showed a cloud of black smoke being left by a plane.
"Something blew up," a man on the video can be heard saying.
In an audio recording, a United pilot could be heard making a mayday call to air traffic control.
"Mayday, aircraft just experienced engine failure, need to turn immediately," according to audio from the monitoring website liveatc.net which was reviewed by Reuters.
Pratt & Whitney, owned by Raytheon Technologies Corp, was not available immediately for comment.
Boeing said its technical advisers are supporting the NTSB with its investigation.© Thomson Reuters 2021