United Airlines Flight 328

Introduction
United Airlines Flight 328 was a passenger flight from Denver to Honolulu. The plane suffered an uncontained engine failure of the right engine and parts of the engine fell onto the ground below. The plane landed safely on Runway 26 at Denver International airport. There were no casualties onboard the plane as well as on the ground. A video taken from the plane featuring the right engine showed that a fan blade was missing. A BBC report can be seen here: https://www.bbc.co.uk/news/world-us-canada-56141673

Background
The aircraft operating Flight 328 was a Boeing 777-200 registered as N772UA. It was delivered to United Airlines in September 1995 and has seen 25 years of service. The aircraft is powered by two Pratt & Whitney PW4077 engines.

There have been previous reports of PW4000 engine failures. In December 2020, Japan Airlines Flight JL904 operating a Boeing 777 suffered a failure of the same engine type at around 16,000. On February 13, 2018, United 1175 en route from San Francisco to Honolulu suffered from an engine failure over the Pacific. The aircraft was a Boeing 777-200, N773UA, with an identical configuration to the aircraft operating Flight 328. The aircraft subsequently landed safely in Honolulu with no injuries or loss of life. The NTSB eventually determined that the cause of the incident was a fractured fan blade in the engine. The investigation faulted Pratt & Whitney for not doing more stringent inspections. The aircraft was eventually repaired and returned to service. On the same day as the incident involving Flight 328, a Boeing 747-400BCF belonging to Longtail Aviation experienced an uncontained engine failure, shortly after departing Maastricht Airport in the Netherlands. Two people were injured by the falling debris. The 747-400BCF was powered by PW4056 engines, a derivative of the PW4000 engine.

Reactions
The National Transportation Safety Board (NTSB) is currently investigating the incident. It was noted upon initial inspection of the right engine that the inlet and the cowling had separated from the engine and that two fan blades had fractured, one near its root and an adjacent one about mid-span; a portion of one blade was embedded in the containment ring. The remainder of the fan blades exhibited damage to the tips and leading edges.

United Airlines has removed all Boeing 777 aircraft with PW4000 engines from active service.