This Saturday, a United Airlines flight experienced a severe engine failure shortly after taking off from Denver International Airport. The aircraft was performing flight UA328, a daily scheduled flight from Denver to Honolulu when the accident happened. The aircraft involved was a 26-year-old Boeing 777-200 registered as N772UA; it was the fifth Boeing 777 that had ever been produced.
Four minutes after taking off from Denver, the pilots of flight 328 declared an engine failure and requested a turn back to the airport. The right engine of the plane had exploded at an altitude of 13,000 feet in the sky, and debris from the engine showered into the suburbs of Denver. Passengers onboard described that the aircraft was vibrating rapidly before they heard a loud boom and the engine exploded. The engine was filled with flames, and the failure was uncontained, meaning that parts of the engine were being stripped off as the aircraft was flying. The pilots did not choose to dump fuel after the failure and proceeded to land with all the extra weight from the fuel. Several minutes later, flight 328 managed to land safely back at Denver. None of the 241 people on board were injured.
During the time of the accident, several residents in the suburbs of Denver reported seeing metal scraps crashing from the sky. Multiple calls were made to the police department regarding this occurrence. The debris from the engine fell across the town, scattering in multiple different locations. The cowling of the engine even crashed onto a resident’s truck and settled in the homeowner’s front yard. Bystanders who observed the plane from the ground recalled seeing black smoke trailing from the back of the engine. Fortunately, also no one on the ground was injured from the incident.
Based on video recordings of the damaged engine from passengers of the plane and an inspection of the plane after it returned back to Denver, officials determined that the engine failure was caused by the fan blades of the type of engine. The type of engine used on the 777 involved in this incident was a Pratt and Whitney PW4000, an engine that contains hollow fan blades. According to investigations, one of the blades of the engine came loose during the flight and ruptured the engine, causing a rare uncontained engine failure. Uncontained failures are more dangerous than other engine failures since fragments are flung out from the engine in an uncontained failure, and those fragments could damage the plane itself. For example, an uncontained engine failure on a Southwest flight punctured a window of the plane and unfortunately killed a passenger in 2018. In this United accident, fragments of the engine did puncture the fuselage of the plane, but luckily not the cabins.
Overall, it was astonishingly fortunate for this incident to play out the way it did. This event could have been much more catastrophic if things had occurred slightly differently. If the flight had experienced the failure over the Pacific Ocean, or if a piece of debris had punctured the main fuselage during the failure, the aftermath of this incident could have ended much differently. The results of this incident have prompted further safety investigations of Boeing 777 aircraft equipped with this particular engine. Since this is not the first time this incident has happened in the past, the FAA is conducting research into the safety of this particular type of aircraft. Several Boeing 777s with this type of engine have already been grounded and are soon going to be inspected by the FAA. This is similar to how the 737 MAX was grounded in 2019, but less severe. Since this is big news for the 777, we will cover this topic in detail in the next article, but for right now, it is great news that everyone involved in this incident was safe and without injury.
Cover image credited to Chad Schnell