BROOMFIELD, Colo. (CBS4) – The administrator of the Federal Aviation Administration, Steve Dickson, says he directed aviation safety experts “to issue an Emergency Airworthiness Directive that would require immediate or stepped-up inspections of Boeing 777 airplanes equipped with certain Pratt & Whitney PW4000 engines.”

(credit: CBS)

READ MORE: Aviation Expert Cautions Against Jumping To Conclusions About United Airlines Flight 328

Dickson says some aircraft will be removed from service.

It’s the same type of plane and engine which suffered a massive problem while flying over Broomfield on Saturday. The engine on United Airlines Flight 328 exploded mid-air and sent debris free-falling onto neighborhoods and parks.

(credit: CBS)

“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 stated.

He adds the FAA is currently meeting with representatives from Boeing and Prattt & Whitney about details in the directive which will include exact details of the inspection.

CNN reports, according to sources, investigators believe a fan blade in the engine of the Boeing 777 came off and hit another blade. The blades are hollow and made of titanium, and are difficult to inspect. The source familiar says cracks propagate from the inside of the hollow blade.

According to the FAA, the U.S., Japan and South Korea are the only countries to use this airplane, and United Airlines is the only U.S. carrier to use this engine.

United Airlines released the following statement about its decision to remove Boeing 777 aircraft:

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. Since yesterday, 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. As we swap out aircraft, we expect only a small number of customers to be inconvenienced.

Safety remains our highest priority – for our employees and our customers. That’s why our pilots and flight attendants take part in extensive training to prepare and manage incidents like United flight 328. And we remain proud of their professionalism and steadfast dedication to safety in our day to day operations and when emergencies like this occur.

United says they have a total of 52 of these aircraft – 28 of which are in storage.

The NTSB is investigating.

Danielle Chavira