Incident Overview
On 27 September 2022, an Avianca Boeing 787-8, registration N781AV, was operating a scheduled commercial flight from Bogotá El Dorado International Airport (SKBO) to London Heathrow (EGLL). The aircraft was cruising at flight level FL410 when, approximately 6 hours and 18 minutes into the flight, engine number one (left side) experienced an uncommanded in-flight shutdown. The crew immediately received three Master Caution alerts on the EICAS: ENG FAIL L, ENG CONTROL L, and ENG EEC C1 L, all associated with the left engine.
Crew Actions and Diversion
The flight crew executed the standard abnormal procedures for an inoperative engine and initiated a descent to FL270. Two manual restart attempts were made but were unsuccessful, and the ENG FUEL VALVE L fault was additionally displayed. The crew declared an emergency to air traffic control and coordinated a diversion to their nearest alternate, Lajes Airport in the Azores. The operator's Dispatch Control Center and Maintenance Control Center in Bogotá assisted via ACARS and SATCOM. The resting first officer was called to the cockpit and swapped with the relief first officer. Cabin crew prepared the cabin for landing. The aircraft landed uneventfully on runway 15 at Lajes Airport at 12:40 UTC. No injuries were reported among the 10 crew and 244 passengers. Aircraft damage was classified as minor.
Aircraft and Engine Details
The Boeing 787-8 is a long-range, wide-body twin-engine airliner manufactured by The Boeing Company. N781AV was delivered on 19 December 2014 and is one of 12 Boeing 787-8s operated by Avianca, powered by Rolls-Royce Trent 1000 engines. The specific engine involved was a Trent 1000 D2 variant, certified on 10 September 2013. The Trent 1000 is a high-bypass turbofan with a three-shaft design and an all-electric architecture. Its external gearbox (EGB) drives generators, alternator, hydraulic pump, and other components.
Inspection Findings
A preliminary inspection of the affected engine revealed a significant crack in the casing of the external gearbox (EGB) and a substantial quantity of oil spilled in that area. The engine had previously undergone a shop visit in May 2018 for intermediate pressure compressor and high-pressure turbine overhaul at 13,372 hours since new. During that visit, wear was discovered on the upper coupling (ADS Assembly). As no wear limits had been published at that time, a technical variance (TV187599) was approved by Rolls-Royce to allow continued service. The report does not state a probable cause for this incident.