B77W, en-route, east of Oman, 2021

B77W, en-route, east of Oman, 2021

Summary

On 12 September 2021, a Boeing 777-300 in cruise at FL380 and approaching Oman from the east at night experienced a sudden left engine failure. The engine was shut down, a PAN call was made, and the crew diverted to Muscat rather than completing the intended flight to Abu Dhabi. An off-wing examination of the GE90 engine found that the hydromechanical unit of the accessory gearbox had malfunctioned in a way which allowed fuel to mix with the engine oil. This failure had not been anticipated in the applicable Fault Identification Manual, which was amended accordingly.

Description

On 12 September 2021, a GE90-115BG03-powered Boeing 777-300 (A6-ETP) operated by Etihad Airways on a scheduled international passenger flight from Dhaka to Abu Dhabi as EY245 was approaching the Omani coast from the east at night in cruise at FL380 when the left engine suddenly became unstable and its indicated thrust reduced to 40% N1. It was shut down, and with a precautionary ‘PAN’ declared, the flight diverted to Muscat. Indications during the previous flight that the same engine may have had a problem were subject to line assessment prior to departure. However, this did not identify the fault, which subsequently worsened en route and necessitated the shutdown.

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