Incident Overview
On 13 April 2022, a Boeing 787-8 aircraft, registration SP-LRF, departed from Warsaw Chopin Airport (EPWA) on flight LO21 to Los Angeles (KLAX). Approximately 37 minutes after takeoff, while at cruising altitude FL360, the flight crew reported an automatic shutdown of engine number 2. The crew successfully performed an in-flight restart of the engine. After the engine reached idle power, the crew observed an inability to increase thrust on engine number 2, along with high N2 (high-pressure turbine) and EGT (exhaust gas temperature) readings. The crew decided to shut down the engine, dump fuel, and return to Warsaw. The aircraft landed at Warsaw Okęcie Airport at approximately 13:41 local time with assistance from airport services. The landing was completed without further incident.
Investigation
The investigation was conducted by the Polish State Commission on Aircraft Accident Investigation (PKBWL). The operator and engine manufacturer performed extensive testing and troubleshooting. Despite these efforts, the investigation did not determine a definitive cause for the engine malfunction. The most probable cause identified was a temporary malfunction of the VSV (Variable Stator Vane) servo valve, likely due to contamination that was later cleared.
Corrective Actions
The following corrective actions were taken by the operator and manufacturer:
- Replacement of the fuel pump
- Replacement of the HMU (Hydromechanical Unit)
- Replacement of both VSV actuators
- Full borescope inspection of the engine – no damage found
- Replacement of the fuel filter – the removed filter showed no contamination
- Inspection of fan blades – no damage; erosion within limits
- Inspection of the VSV system linkage – no damage
- Tests of the VSV and handling bleed valves – passed successfully
- Post-component replacement tests – passed
- Troubleshooting of vibration transmitters – no physical damage; tests passed
- Engine run at idle and high power – all parameters stable and within limits
Additionally, on engine number 1, the operator replaced the fuel filter and performed a VSV system test, which passed. Engine parameters on number 1 were also stable during testing.
Conclusion
The investigation concluded without a definitive root cause. No safety recommendations were issued.