United Airlines grounds 24 Boeing 777s from service

United Airlines is removing all of its Boeing 777 planes currently in service that are powered by Pratt & Whitney 4000 series engines after one of its jets suffered engine failure after take-off on Saturday.

The plane_ carrying 231 passengers and 10 crew_ was forced to return to Denver airport. No injuries were reported.

The airline announced Sunday it was immediately removing the planes "out of an abundance of caution." The 24 aircraft are part of the 52 777s in the United fleet. The other 28 remain in storage.

The move is voluntary and temporary_ United said_ and should disrupt only "a small number of customers."

The announcement came after the FAA issued an emergency order saying it would be stepping up inspections of Boeing 777 airplanes equipped with certain Pratt & Whitney PW4000 engines.

"We reviewed all available safety data following yesterday's incident_" FAA Administrator Steve Dickson said_ referring to the United Airlines flight that was forced to return to Denver International Airport on Saturday after it suffered an engine failure shortly after takeoff_ causing debris to fall in greater Denver.
"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_" Dickson said.

The National Transportation Safety Board said Sunday an initial examination of the Pratt & Whitney PW4077 engine from United Airlines Flight 328 showed that two fan blades were fractured and the remaining blades exhibited damage "to the tips and leading edges."

These are preliminary findings and should not be taken as conclusive of what went wrong Saturday_ but they are still significant.

Investigators believe a fan blade in the engine of the Boeing 777 that experienced a catastrophic engine failure on Saturday came off and took out another blade_ a source familiar with the situation told CNN.

"While the NTSB investigation is ongoing_ we recommended suspending operations of the 69 in-service and 59 in-storage 777s powered by Pratt & Whitney 4000-112 engines until the FAA identifies the appropriate inspection protocol_" Boeing's statement read.

According to the Federal Aviation Administration (FAA)_ United is the only US airline flying such planes_ with the others being in Japan and South Korea.

Japan's transportation ministry said it has ordered the country's domestic airlines to halt operations of Boeing 777 aircraft equipped with Pratt & Whitney PW4000 engines.