United Airlines Flight 1175

On February 13, 2018, around noon local time, a Boeing 777 operating as United Airlines Flight 1175 (UA1175), experienced an in-flight separation of a fan blade in the No. 2 (right) engine while over the Pacific Ocean en route from San Francisco International Airport to the Daniel K. Inouye International Airport, Honolulu, Hawaii. During level cruise flight shortly before beginning a descent from flight level 360 (roughly 36000 ft), and about 120 mi from the destination, the flight crew heard a loud bang, followed by a violent shaking of the airplane, followed by warnings of a compressor stall. The flight crew shut down the failed engine, declared an emergency, and began a drift-down descent, proceeding direct to the Daniel K. Inouye International Airport where they made a single-engine landing without further incident at 12:37 local time. There were no reported injuries to the 378 passengers and crew on board and the airplane damage was classified as minor under National Transportation Safety Board (NTSB) criteria.

NTSB investigators traveled to the scene to begin an incident investigation. They found a full-length fan blade fracture in the No. 2 (right) engine, a Pratt & Whitney (P&W) PW4077 turbofan. Its installed set of hollow-core fan blades had undergone two previous overhauls at P&W that included a thermal acoustic imaging (TAI) internal inspection that is intended to prevent this type of failure. The right engine nacelle lost most of the inlet duct and all of the left and right fan cowls immediately after the engine failure. Two small punctures were found in the right side fuselage just below the window belt with material transfer consistent with impact from pieces of an engine fan blade. The damage was eventually repaired and the aircraft returned to service. Improved procedures for TAI inspection were implemented by P&W, increased frequency of TAI inspection was required by regulators, and a redesign of the inlet duct was also initiated by Boeing, all as a result of this incident and investigation.

Incident

The flight departed SFO on time and the push back, taxi, takeoff, and climb were normal. There were three pilots on the flight deck: Captain Christopher Borzu Behnam (57), who was the pilot monitoring, First Officer (FO) Paul Ayers (60), who was the pilot flying, and a jump seat rider, who was off-duty United Airlines 777 First Officer Ed Gagarin. The captain reported a total of 13,592 hours total time, with 360 hours in the Boeing 777. The first officer reported a total of 11,318 hours total time, with 10,087 in the Boeing 777.

At the time of the fan blade out engine failure event, 11:58 Hawaiian standard time (HST), the flight was about 120 mi from HNL at flight level (FL) 360 (roughly 36000 ft) when there was a violent jolt and very loud bang that both pilots stated was followed by extreme airframe vibrations. The pilots reported that immediately after the jolt and loud bang, the autopilot disconnected, and the airplane began to roll to the right. A positive exchange of controls was accomplished with the captain becoming pilot flying. The pilots stated that about 15 to 30 seconds after the jolt and loud bang, the Engine Indicating and Crew Alerting System (EICAS) showed that there was no engine pressure ratio (EPR), N1, or oil pressure. After completing the Severe Engine Damage checklist, the crew shut down and secured the right engine. The jump seat rider stated that after the right engine was shut down, the vibration subsided although the controllability of the airplane was not normal. The crew declared an emergency and began a drift down descent to FL 230 (roughly 23000 ft).

The captain directed the jump seat rider to go back into the cabin to assess the condition of the engine. The jump seat rider noted that the engine was oscillating and that the cowling was missing. He took a video of the engine to show the captain and the FO the engine's condition. The pilots reported that concurrently, the purser had come to the flight deck and the captain briefed her about the emergency and that they would be landing at HNL. The crew decided the most suitable airport in time, distance, and familiarity was HNL. The airplane continued to HNL and made a visual approach and landed on Runway 8R without further incident. The pilots stated that the aircraft rescue and firefighting (ARFF) personnel inspected the airplane and when the airplane was determined to be safe, they taxied the airplane to the gate where the passengers deplaned normally. The 363 passengers, 3 pilots, and 12 flight attendants board deplaned normally at the gate and there were no injuries.