N773UA

HISTORY OF FLIGHTOn February 13, 2018, about 1200 Hawaiian standard time (HST), United Airlines flight 1175, a Boeing 777-222, N773UA, experienced an in-flight separation of a fan blade as well as portions of the inlet and fan cowl of the No. 2 (right) engine, a Pratt & Whitney (P&W) PW4077, over the Pacific Ocean enroute to the Daniel K. Inoyue International Airport (HNL), Honolulu, Hawaii. While the airplane was in level cruise flight at flight level (FL) 360, the flight crew heard a loud bang that was followed by a violent shaking of the airplane followed by warnings of a compressor stall. The flight crew shut down the engine, declared an emergency, and proceeded to HNL without further incident. There were no injuries to the 374 passengers and crew onboard and the airplane received minor damage. The flight was operating under the provisions of 14 Code of Federal Regulations Part 121 as a regularly scheduled passenger flight from the San Francisco International Airport, San Francisco, California (SFO) to HNL.

At the time of the event, there were three pilots on the flight deck: the captain, who was the pilot monitoring, the first officer (FO), who was the pilot flying, and a jump seat rider, who was an off-duty United Airlines 777 FO.

The flight departed SFO on time and the push back, taxi, takeoff, and climb were normal. The flight was about 120 miles from HNL at flight level (FL) 360 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 instruments indicated a failure of the number 2 engine. After accomplishing the Severe Engine Damage checklist, the crew shut down and secured the engine. The jump seat rider stated that after the right engine was shutdown, 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. 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 what they were dealing with. 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 airplane continued to HNL and made a visual approach and landed on Runway 8R without further incident. PERSONNEL INFORMATIONThe captain, age 57, reported a total of 13,592 hours total time, with 360 hours in the B777. He held an FAA Airline Transport Pilot certificate with type ratings in the B777, B747, B737, B757, B767, and SD-3. He held a valid first class medical certificate with a restriction for glasses for near vision. His most recent flight review was October 10, 2017.

The first officer, age 60, reported a total of 11,318 hours total time, with 10,087 in the B777. He held an FAA Airline Transport Pilot certificate with type ratings in the B777 and B747. He held a valid first class medical certificate with a restriction for glasses for near vision. His most recent flight review was October 3, 2017. AIRCRAFT INFORMATIONThe Boeing 777-200 is a long-range, wide-body, twin-engine airplane, with a maximum takeoff weight of 545,000 pounds. The incident airplane was equipped with P&W PW4077 turbofans. The airplane had accumulated 89,723 hours and 16,339 cycles since new.

The PW4077 is a dual-spool, axial-flow, high bypass turbofan engine that features a 1-stage 112-inch diameter fan, 6-stage low pressure compressor (LPC), 11-stage high pressure compressor (HPC), annular combustor, 2-stage high pressure turbine (HPT) that drives the HPC, and a 7-stage low pressure turbine (LPT) that drives the fan and LPC.

According to United Airlines' maintenance records, the No. 2 engine had accumulated 77,593 hours time since new (TSN) and 13,921 cycles since new (CSN) and 8,579 hours and 1,464 cycles since the last overhaul. The engine was installed on the airplane on October 18, 2015, at an airplane time and cycles since new of 81,144 hours and 14,875 cycles, respectively. The engine had operated 8,579 hours and 1,464 cycles since it had been installed.

The PW4000 112-inch engine fan blade is a hollow core, wide chord airfoil made of a titanium alloy with 6 percent vanadium and 4 percent aluminum as alloying elements. The fan blade is about 40.5-inches long from the base of the blade root to the tip of the airfoil and about 12.5- and 22.25-inches wide at the blade root and blade tip, respectively. A fan blade weighs a maximum of 34.85 pounds.

The inlet is a cantilevered structure that directs the airflow into the fan case in a controlled and uniform manner. The inlet consists of two concentric cylinders (the inner and outer barrels) joined by forward and aft bulkheads and a lip skin. The inlet aft bulkhead was constructed of CFRP on the production airplanes. During engine fan blade out (FBO) certification testing the inlet cowl construction consisted of an aluminum bulkhead. The inlet is bolted to the forward end of the fan case though an attach ring using 44 bolted connections. Loads and displacements resulting from a fan blade out event (FBO) are transferred between the inlet and the engine fan case though the attachment bolts and the attachment ring.

The fan cowls are two cylindrical halves located aft of the inlet that enclose the engine fan case and the external engine accessories which provides a smooth aerodynamic surface over the core of the engine fan case. The fan cowls are supported on the forward end by the inlet and on the aft end by the thrust reverser. Additionally, the fan cowls are attached to the fan cowl support beam using four hinges (total of eight) at the top and latched (four latches) at the bottom to allow for the fan cowls to be opened for maintenance.

The engine is certified under FAR part 33 regulations. To comply with the regulations, the engine successfully demonstrated containment and safe shutdown of an engine after intentional fracture of a fan blade at redline speed. Although it is necessary to install an inlet for proper engine operation during these tests, it is not required that this inlet meet production standards. The test inlet used was of a different design which included an aluminum aft bulkhead instead of the production CFRP aft bulkhead. Additionally, these tests are conducted without the fan cowls attached. The inlet and fan cowls are certified under FAR Part 25 of which Boeing was responsible for. AIRPORT INFORMATIONThe Boeing 777-200 is a long-range, wide-body, twin-engine airplane, with a maximum takeoff weight of 545,000 pounds. The incident airplane was equipped with P&W PW4077 turbofans. The airplane had accumulated 89,723 hours and 16,339 cycles since new.

The PW4077 is a dual-spool, axial-flow, high bypass turbofan engine that features a 1-stage 112-inch diameter fan, 6-stage low pressure compressor (LPC), 11-stage high pressure compressor (HPC), annular combustor, 2-stage high pressure turbine (HPT) that drives the HPC, and a 7-stage low pressure turbine (LPT) that drives the fan and LPC.

According to United Airlines' maintenance records, the No. 2 engine had accumulated 77,593 hours time since new (TSN) and 13,921 cycles since new (CSN) and 8,579 hours and 1,464 cycles since the last overhaul. The engine was installed on the airplane on October 18, 2015, at an airplane time and cycles since new of 81,144 hours and 14,875 cycles, respectively. The engine had operated 8,579 hours and 1,464 cycles since it had been installed.

The PW4000 112-inch engine fan blade is a hollow core, wide chord airfoil made of a titanium alloy with 6 percent vanadium and 4 percent aluminum as alloying elements. The fan blade is about 40.5-inches long from the base of the blade root to the tip of the airfoil and about 12.5- and 22.25-inches wide at the blade root and blade tip, respectively. A fan blade weighs a maximum of 34.85 pounds.

The inlet is a cantilevered structure that directs the airflow into the fan case in a controlled and uniform manner. The inlet consists of two concentric cylinders (the inner and outer barrels) joined by forward and aft bulkheads and a lip skin. The inlet aft bulkhead was constructed of CFRP on the production airplanes. During engine fan blade out (FBO) certification testing the inlet cowl construction consisted of an aluminum bulkhead. The inlet is bolted to the forward end of the fan case though an attach ring using 44 bolted connections. Loads and displacements resulting from a fan blade out event (FBO) are transferred between the inlet and the engine fan case though the attachment bolts and the attachment ring.

The fan cowls are two cylindrical halves located aft of the inlet that enclose the engine fan case and the external engine accessories which provides a smooth aerodynamic surface over the core of the engine fan case. The fan cowls are supported on the forward end by the inlet and on the aft end by the thrust reverser. Additionally, the fan cowls are attached to the fan cowl support beam using four hinges (total of eight) at the top and latched (four latches) at the bottom to allow for the fan cowls to be opened for maintenance.

The engine is certified under FAR part 33 regulations. To comply with the regulations, the engine successfully demonstrated containment and safe shutdown of an engine after intentional fracture of a fan blade at redline speed. Although it is necessary to install an inlet for proper engine operation during these tests, it is not required that this inlet meet production standards. Th...