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13th of February 2018

A Boeing 777-222 was en route from San Francisco International Airport (California, USA) to Honolulu International Airport (Hawaii, USA). After an uneventful flight while cruising at FL 360 just prior to reaching the top of descent (120 miles from Honolulu) the crew heard a loud bang and the aircraft violently jolted, followed immediately by violent vibrations and a warning of a compressor stall on the right hand Pratt & Whitney (P&W) PW4077 turbofan.

The failed Pratt & Whitney (P&W) PW4077 turbofan (source; NTSB)

Immediately after the occurrence the autopilot disconnected and the aircraft had a tendency to roll to the right

With a right-hand failure indicated and the vibrations, a serious engine issue was apparent and the crew completed the Severe Engine Damage checklists was completed the engine was shut down. Although the vibrations had subsided the controllability of the aircraft was not normal. ATC was contacted and an emergency was declared, and the crew started a drift down to flight level 230 while continuing to Honolulu. Besides the two pilots, an off-duty Boeing 777 Forts Officer was in the cockpit as a jump seat rider. The Captain requested the jump seat rider to go into the cabin to visually assess the status of the right-hand engine. When he came back into the flight deck the jump seta rider reported the engine was oscillating and that the cowlings were missing, he showed the pilots a video he had made of the situation. The purser was briefed about the situation and that they were expecting a single-engine landing at Honolulu.

Close-up of the failed fanblades (Source Aerossurance)

The aircraft continued to Honolulu where a visual approach and a successful landing was made at runway 8R without further issues arising. According to the operator's 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.

Close up of the failed fanblade (Source; Aerossurance)

The engine failure was investigated by the National Transportation Safety Board, and it was found that a fanblade had broken at the root, across the airfoil. and an adjacent fanblade had failed at ~3/4 span from the blade root. A piece of the fanblade was found against the fan exit guide vanes at the 4 o'clock position. Metallurgical examination of the failed fanblade revealed a fatigue fracture that had initiated from a subsurface origin in a region of micro texturing consisting mostly of primary alpha crystals on the interior surface of the hollow core fan blade. The examination also revealed that the fan blade's material conformed to the specified titanium alloy's requirements. The failure of the fanblade had caused an unbalance in the fan which caused the vibrations. Several cracks were found in the Kevlar containment ring, Some parts of the aircraft had light damage (Scratches) caused by debris ejected from the bypass duct;

  • Righthand main landing gear door

  • The right-wing

  • The right horizontal stabiliser

The engine inflight (© @erikhaddad/Twitter)

The NTSB report with more details on this engine failure is available by clicking on the link below;

B777 Fanblade Failure
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