Why have Boeing 777s been removed from service after the Denver incident?
United Airlines has grounded 24 Boeing aircrafts after an engine failure on a flight to Honolulu sent debris falling onto a Denver residential area.
Plane manufacturer Boeing have called for operators to temporarily ground some of their 777-model aircrafts after an engine caught fire and shed debris over Denver last Saturday. The advice only applies to 777s that use the same engine as the one that suffered the failure.
The incident happened on a United Airlines-operated flight from Denver International Airport on Saturday, which was due to land in Honolulu. But just minutes after taking off a significant failure to the right engine forced the flight to return to Denver, dropping engine parts onto residential areas around the city.
The grounded aircrafts are those fitted with Pratt & Whitney 4000 engines similar to that used on the Honolulu flight. At this stage it is thought that the fault was caused by damage to the fan blade inside the unit.
Flights grounded until further notice
In the immediate aftermath of the incident in Denver, Boeing advised operators around the world to halt the use of similar models until they have had a chance to carry out a more thorough investigation.
In total 128 jets around the world will be affected by the guidance, 24 of which were a part of United’s fleet. Most of the other potentially affected planes are owned by South Korean or Japanese operators. Asiana Airlines of South Korea have decided to ground the nine 777s in their fleet but Korean Air are yet to do so, and are awaiting guidance from the country’s transport ministry.
In response to the incident the Federal Aviation Administration (FAA) have issued a statement saying they have “reviewed all available safety data following [Saturday's] incident.”
"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."
Investigations continue into the source of the Boeing 777 failure
Following the Denver incident both Boeing and Pratt & Whitney have assisted with an investigation into what happened, and have released statements on the suspected engine failure.
"We are pleased to hear that United Airlines flight 328 returned safely to Denver," said Boeing, who manufacture the 777 aircraft. "Boeing technical advisers are supporting the US National Transportation Safety Board with its investigation."
While Boeing produce the plane the 777 engines are made by Pratt & Whitney, a subsidiary of Raytheon Technologies, who specialise in aeronautical engineering.
"Pratt & Whitney is actively coordinating with operators and regulators to support the revised inspection interval" of the 4000 engines that was involved in the failure on Saturday, they said in a statement. The company added that "any further investigative updates regarding this event will be at the discretion of the NTSB."