What happened
On April 13, 2022, a Boeing 787-8, registration SP-LRF, was operating flight LO21 from Warsaw Chopin Airport (EPWA) to Los Angeles (KLAX). Approximately 37 minutes into the flight, while cruising at FL360 within the Warsaw FIR, the crew reported an uncommanded shutdown of the number 2 engine.
The crew successfully performed an in-flight restart of the engine. However, once the engine reached idle speed, the crew observed that power could not be increased. This was accompanied by high N2 (high-pressure turbine) speeds and elevated Exhaust Gas Temperature (EGT). Due to these parameters, the crew elected to shut down the engine, perform a fuel dump, and return to Warsaw. The aircraft landed at Warsaw Chopin Airport at approximately 13:41 local time under the assistance of airport emergency services. The landing was completed without further incident.
The investigation
The PKBWL examined the engine's performance and the mechanical components involved in the failure. The investigation included extensive testing by both the operator and the engine manufacturer. Maintenance actions taken following the event included the replacement of the fuel pump, the Hydromechanical Unit (HMU3), both Variable Stator Vane (VSV) actuators, and the fuel filter.
Technical inspections, including a full borescope of the engine, fan blade inspections, and VSV system linkage checks, revealed no physical damage or erosion. Subsequent ground testing of the engine at both idle and high power settings showed all parameters to be stable and within limits, with no active error messages recorded on the Common Centralized Fault Display (CMCF).