United Airlines engine explosion over Denver prompts company to ground Boeing 777s

Federal aviation regulators are ordering United Airlines to step up inspections of all Boeing 777s equipped with the type of engine that suffered a catastrophic failure over Denver on Saturday. United said it is temporarily removing those aircraft from service.

The announcements came a day after United Airlines Flight 328 had to make an emergency landing at Denver International Airport after its right engine blew apart just after takeoff. Pieces of the casing of the engine, a Pratt & Whitney PW4000, rained down on suburban neighborhoods.

Separately, Dutch authorities were investigating a strikingly similar incident in which a Boeing 747-400 cargo plane dropped engine parts shortly after taking off from Maastricht airport Saturday, according to Reuters. An airport spokesperson said small metal parts were scattered over the southern town of Meerssen. There was some damage and a woman was hurt. It landed safely.

The plane in the U.S., with 231 passengers and 10 crew on board, also landed safely. No one aboard or on the ground was reported hurt, authorities said.

Federal Aviation Administration 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."

The National Transportation Safety Board said in a separate statement that two of the engine's fan blades were fractured and the remainder of the fan blades "exhibited damage." The NTSB did caution that it was too early to draw conclusions about how the incident happened.

Boeing said it's recommending that "operations of the 69 in-service and 59 in-storage 777s" with the Pratt & Whitney engines worldwide be suspended "until the FAA identifies the appropriate inspection protocol."

Pratt & Whitney issued a statement saying it "has dispatched a team to work with investigators" and is "actively coordinating with operators and regulators to support the revised inspection interval" of the engines involved.

Video posted on Twitter 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 posted on Twitter appeared to show a broken fan blade in the engine.

United is the only U.S. airline with the Pratt & Whitney PW4000 in its fleet, the FAA said. United said it currently has 24 of the 777s in service.

United said it will work closely with the FAA and the NTSB "to determine any additional steps that are needed to ensure these aircraft meet our rigorous safety standards and can return to service."

The NTSB said the cockpit voice recorder and flight data recorder were transported to its lab in Washington for the data to be downloaded and 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.

Airlines in Japan and South Korea also operate planes with the Pratt & Whitney engine. Japan Airways and All Nippon Airways have decided to stop operating a combined 32 planes with that engine, according to Nikkei.

Nikkei reported that Japan's Ministry of Land, Infrastructure, Transport and Tourism also ordered the planes out of service, and the ministry said an engine in the same PW4000 family suffered unspecified trouble on a JAL 777 flying to Haneda from Naha on December 4. It ordered stricter inspections in response.

Korean Air said Monday that it grounded its 16 777s with the Pratt & Whitney engines.

Boeing said it "supports the decision ... by the Japan Civil Aviation Bureau" and "the FAA's action" to suspend operations the 777s that have the Pratt & Whitney engines.

"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 added.

In the Netherlands, the airport spokesperson was quoted by Reuters as saying photos seemed to show that the parts that fell to the ground were from of an engine blade, but that was being investigated.

Witnesses said they saw one engine on fire. The plane landed safely at Liege airport in Belgium, some 19 miles south of Maastricht.

The cargo plane had a Pratt & Whitney PW4000 engine, a smaller version of one on the United Airlines 777 involved in the incident over Denver, Dutch authorities said.

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• Airplane Crash
• Explosion
• United Airlines