Boeing has recommended that airlines ground all 777s with the type of engine that blew apart after takeoff from Denver this weekend, and most carriers that fly those planes said they would temporarily pull them from service.

United Airlines is the only American carrier with those planes. The others are flown by Asian airlines in Japan and Korea.

The U.S. Federal Aviation Administration ordered United Airlines to step up inspections of the aircraft after one of its flights made an emergency landing at Denver International Airport Saturday as pieces of the casing of the engine, a Pratt & Whitney PW4000, rained down on Broomfield neighborhoods.

None of the 231 passengers or 10 crew were hurt, and the flight landed safely. United is among the carriers that has grounded the planes.

FAA Administrator Steve Dickson said in a statement Sunday that based on an initial review of safety data, inspectors “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.”

United immediately grounded its 24 Boeing 777 airplanes that were in service. It has another 28 in storage.

“Starting immediately and out of an abundance of caution, we are voluntarily and temporarily removing 24 Boeing 777 aircraft powered by Pratt & Whitney 4000 series engines from our schedule,” according to a statement Sunday. “We’ve been in touch with regulators at the NTSB and FAA and will continue to work closely with them to determine any additional steps that are needed to ensure these aircraft meet our rigorous safety standards and can return to service.”

Officials expected “only a small number of customers to be inconvenienced,” but declined to elaborate Monday or respond to inquiries from The Denver Gazette on impact to Denver travelers or its DIA operations. They also did not respond to requests to speak to the flight crew.

Aviation attorney Ladd Sanger, of Dallas based Slack Davis Sanger, told The Denver Gazette Monday they applauded the FAA’s decision to require more engine inspections.

“A one-off failure is a serious event to source the root cause,” said Sanger, who is also a pilot. “But when you have two like this in such a short period of time, that means the manufacturer is pushing the service life of those rotating blades further. … Having these failures occur in operation means the service life of some parts has gone too long.”

Sanger’s firm represented passengers in the Southwest Flight #1380 incident in 2018 where engine failure sent shrapnel through a cabin window, causing a passenger to get partially sucked out and die.

He said it’s troubling the engine casing didn’t hold all the broken flying engine parts, as its designed to do. Those changes came after United Airlines flight #232 crashed near the Sioux City airport in July 1989, after taking off from Denver. A tail engine failed and shrapnel shredded the hydraulic control lines. Due to heroic efforts from the DC-10’s pilots, 184 of the 296 people on board survived.

The FAA “is likely going require the more frequent replacement of those engine components, which will greatly enhance the safety of the engine,” Sanger said. “It’s overdue and needs to happen now for sure.”

In yet a third incident – which also happened Saturday – two people were injured in the Netherlands when a Boeing 747 carrying cargo experienced engine failure shortly after takeoff from Maastrict, according to multiple news reports. It landed safely in Belgium, but the falling debris injured people on the ground and caused property damage.

Japan ordered the planes out of service, according to the financial newspaper Nikkei, while noting that an engine in the same family suffered trouble in December.

Boeing said there were 69 777s with the Pratt & Whitney 4000-112 engines in service and another 59 in storage.

United is the only U.S. airline with the engine in its fleet, according to the FAA. Two Japanese airlines have another 32 that are being pulled while Asiana Airlines grounded nine, seven of which were in service, until Boeing establishes a plan to fix the problems. Korean Air said it was discussing whether to ground 16 aircraft, six of which are in service.

“We are working with these regulators as they take actions while these planes are on the ground and further inspections are conducted by Pratt & Whitney,” Boeing said in a statement issued Sunday, referring to American and Japanese regulators.

The engine maker said it was sending a team to work with investigators.

Video posted on Twitter from Saturday’s emergency showed the engine fully engulfed in flames as the plane flew through the air. Freeze frames from different video taken by a passenger sitting slightly in front of the engine and also posted on Twitter appeared to show a broken fan blade in the engine.

Passengers, who were headed to Honolulu, said they feared the plane would crash after an explosion and flash of light, while people on the ground saw huge chunks of the aircraft pour down, just missing one home and crushing a truck. The explosion, visible from the ground, left a trail of black smoke in the sky.

The U.S. National Transportation Safety Board said that two of the engine’s fan blades were fractured and the remainder of the fan blades “exhibited damage.” But it cautioned that it was too early to draw conclusions about what happened.

The NTSB said the cockpit voice recorder and flight data recorder were transported to its lab in Washington so the data can be analyzed. NTSB investigations can take up to a year or longer, although in major cases the agency generally releases some investigative material midway through the process.

Japan’s Ministry of Land, Infrastructure, Transport and Tourism said an engine in the PW4000 family suffered trouble on a Japan Airlines 777 flying to Tokyo from Naha on Dec. 4. The airline has said the plane had engine trouble after takeoff and returned to Naha. An inspection showed damage to the engine case and missing fan blades, according to the airline. Stricter inspections were ordered in response.

Japan Airlines and All Nippon Airways will stop operating a combined 32 planes with that engine, Nikkei reported.

Denver Gazette Reporter Dennis Huspeni contributed to this report.