United Airlines announced on Sunday that 24 of its Boeing 777s will be temporarily decommissioned after one of the aircraft suffered an engine failure over the weekend.

The head of the Federal Aviation Administration said Sunday the agency would order the inspection of some Boeing 777 jetliners powered by the same Pratt and Whitney engine, the PW4077.

The Japanese aviation authority has ordered airlines to suspend flights from aircraft with this type of engine until further notice, according to the FAA. United is the only US airline with this type of engine in its fleet, the agency added.

United Flight 328, a Boeing 777-200 bound for Honolulu, landed at Denver International Airport shortly after take-off on Saturday afternoon after the right engine failed.

No one was injured in the flight, which carried 229 passengers and 10 crew members, but debris, including part of the engine cover, fell in nearby Broomfield, Colorado.

United Airlines flight UA328, carrying 231 passengers and 10 crew members, is returning to Denver International Airport with its starboard engine burning after it set off a Mayday alarm over Denver, Colorado, USA on February 20, 2021.

Hayden Smith / @ speedbird5280 | via Reuters

Separately, Boeing recommended stopping its 777 aircraft on the same engine as the United flight, which dropped debris near Denver.

“While the NTSB investigation is ongoing, we have recommended that the 69 operational and 59 in-store 777s with Pratt & Whitney 4000 engines be ceased until the FAA determines the appropriate inspection protocol,” Boeing said in a statement.

The shares of Raytheon Technologies, parent company of engine makers Pratt and Whitney, fell 0.7%, while Boeing rose 1%.

Federal investigators said their initial investigation found two of the correct motor’s fan blades were broken.

The National Transportation Safety Board said one of the engine’s fan blades broke near its root, while another broke halfway. Other engine fan blades were also damaged, the NTSB said in an initial report late Sunday.

“We checked all available safety data after yesterday’s incident. Based on the initial information, we concluded that the inspection interval for the hollow fan blades, which applies only to this engine model, which is only used in Boeing 777 aircraft, has been extended should be, “FAA Administrator Steve Dickson said in a statement.

United has another 28 of these aircraft in its fleet that are currently in storage. Airlines parked or retired dozens of planes after demand plummeted due to the Covid-19 pandemic. The aircraft are also used in Japan and South Korea.

Engine makers Pratt and Whitney said in a statement that they had sent a team to work with US investigators. The company said it “is actively coordinating with operators and regulators to support the revised inspection interval of the Pratt & Whitney PW4000 engines that power Boeing 777 aircraft.”

Residents take photos of debris that fell from the engine of a United Airlines aircraft in the Broomfield neighborhood outside of Denver, Colorado on February 20, 2021. A United Airlines flight suffered a fiery engine failure shortly after taking off from Denver on Feb. 20 en route to Hawaii, where massive debris is falling on a residential area before a safe emergency landing, officials said.

Chet Strange | AFP | Getty Images

Pratt and Whitney said it would continue to ensure the safe operation of the fleet.

United operates 44 other Boeing 777s powered by General Electric engines.

Such incidents are rare but have occurred recently and regulators are likely to investigate common issues.

Dutch regulators are investigating an engine fire in a Boeing 747 cargo aircraft, also powered by Pratt and Whitney PW4000 engines, after parts of one of the engines fell shortly after take-off from Maastricht.

One of the Pratt and Whitney PW4000 engines on a Japan Airlines Boeing 777-200 in Tokyo failed during a flight on December 4 and was forced to return to Naha, Japan. Damage to the fan blade was later discovered. Japan Airlines said it had stepped up its maintenance program as a result of the incident.

In February 2018, another United Airlines 777-200, equipped with Pratt and Whitney PW4077 engines that were involved in the incident outside Denver on Saturday, suffered an engine failure over the Pacific near Hawaii after a Fan blade was broken in June. The incident prompted Pratt & Whitney to step up their fan blade inspection processes. The flight made it safely to Honolulu with 364 passengers and 10 crew members.

In April 2018, a passenger was killed when a fan blade broke off the engine of a Southwest Airlines Boeing 737, broke a window and briefly sucked the passenger outside. Federal regulators ordered airlines to step up fan blade inspection of these engines following the incident.