Feb. 21 (UPI) -- United Airlines said Sunday it was temporarily removing 24 of its Boeing 777 aircraft from service a day after one of its flights had to make an emergency landing due to engine failure.
The announcement from United came about an hour after the Federal Aviation Administration said it was increasing inspections of Boeing 777 aircraft, which would "likely mean that some airplanes will be removed from service."
United said via Twitter the planes "voluntarily & temporarily" pulled from service were powered by the same Pratt & Whitney 4000-112 series engine used in the Denver-to-Honolulu Flight 328 on Saturday when engine failure shortly after takeoff caused it to litter debris over the town of Broomfield, Colo., about 32 miles from the Denver airport.
The two-engine plane was forced to return to the Denver airport where no injuries were reported among the 229 passengers and 10 crew members on board.
The Broomfield Police Department said Sunday that it has been "inundated with debris calls" and instructed the public "to only contact us now if they find a large piece of the plane."
United said they are working closely with regulators to determine steps that need to be taken, which should only inconvenience "a small number of customers."
Steve Dickson, the FAA administrator, said the stepped-up inspections should focus on the hollow fan blades unique to the Pratt & Whitney 4000 series engine that is solely used on Boeing 777 aircraft.
Safety experts with the FAA were expected to have a meeting with Pratt & Whitney and Boeing Sunday night "to ensure that the appropriate airplanes are included in the order," he said.
An initial examination of the Denver-to-Honolulu 777 aircraft indicates damage was confined to one of its two engines, resulting in the plane itself sustaining minor damage, the National Transportation Safety Board said Sunday in a news release.
The examination revealed that the inlet and cowling had separated from the engine and that two fan blades were fractured, one near the root and the other about mid-span. A portion of one blade had become lodged in the containment ring and the remains of the fan blades show "damage to the tips and leading edges," the NTSB said.
Japan's aviation regulator, the Civil Aviation Bureau, separately announced airlines have been instructed to suspend the operation of the aircraft with the identified engine "while considering the necessity of countermeasures."
In a statement, it said a Japan Airlines flight powered by the Pratt & Whitney 4000 series engine from Naha to Tokyo on Dec. 4 had to return to the airport due to a problem with the left engine after flying some 62 miles.
"Currently, we are requesting the Federal Aviation Administration of the United States to investigate the cause of this case and prevent recurrence, and we are collecting information on this case as well, but in order to ensure safety Japan Airlines and All Nippon Airways today in response ordered the aircraft to be suspended," it said.
Japan Airlines has 13 affected aircraft and All Nippon Airways has 19, it said.
Boeing in a statement Sunday night said it has recommended suspending operations of all 777s powered by Pratt & Whitney 4000-112 engines until the FAA identifies inspection protocol.
"Boeing supports the decision yesterday by the Japan Civil Aviation Bureau and the FAA's action today to suspend operations of 777 aircraft powered by Pratt & Whitney 4000-112 engines," Boeing said. "We are working with these regulators as they taken actions while these planes are on the ground and further inspections are conducted by Pratt & Whitney."
There are 69 Boeing 777s with the identified engine in service and 59 in storage, it said.
Pratt & Whitney, a Raytheon technologies company, confirmed the aircraft is under NTBS investigation in a statement, saying it has deployed a team to work with investigators.
"Pratt & Whitney is actively coordinating with operators and regulators to support the revised inspection internal of the Pratt & Whitney PW4000 engines that power Boeing 777 aircraft," it said.
The first fatal crash involving the 777 was on July 6, 2013, when South Korea's Asian Airlines Flight 214, en route to the San Francisco International Airport from Seoul, crashed on the runway, killing three and injuring 187, including 49 seriously, of the 307 people on board.
On March 8, 2014, a Boeing 777 operated by Malaysia Airlines disappeared while en route to Beijing with 227 passengers and 12 crew on board. Several pieces of marine debris confirmed to be from the aircraft washed ashore in the western Indian Ocean in 2015 and 2016.
The 777 made its maiden flight on June 12, 1994, and United Airlines was the first carrier to fly the plane a year later.