Incident Overview
On 27 February 2017 at approximately 10:24 UTC, the Polish State Commission on Aircraft Accident Investigation (PKBWL) was notified by Bratislava ACC that the crew of a Boeing 787-800 (registration SP-LRF) operating flight LOT6523 from Warsaw to Mauritius had reported a technical issue with the left engine (vibrations above the permissible level) and decided to return to Warsaw Chopin Airport (EPWA).
Timeline
Two minutes before crossing the state border, the crew requested a 10-minute fuel dump at FL330. Bratislava ACC did not authorize the fuel dump. The fuel dump began after entering Polish airspace at 10:29 UTC and concluded at 10:38 UTC. At 10:39 UTC, the crew reported 252 persons on board and 29.5 tonnes of fuel remaining, stated no dangerous goods, and neither declared an emergency nor requested landing assistance. Warsaw Tower informed relevant services and declared a first-degree alarm at 10:40 UTC. The aircraft landed on runway 33 at 11:03 UTC, taxied to stand 45 at 11:08, and the alarm was cancelled at 11:12 UTC.
Aftermath
The crew submitted an Air Safety Report, and the aircraft was handed over to technical services. A boroscopic inspection of the left engine revealed damage to the high-pressure turbine blades. The engine was classified for replacement and sent for overhaul.
Cause
The cause of the incident was damage to the high-pressure turbine blades of the left engine.
Safety Actions
The operator (LOT Polish Airlines) recorded the event in its SMS database, classified it according to its criteria, and included it in safety performance indicators monitored under its Safety Management System Manual. No systemic changes or recommendations were made by the commission.
No injuries were reported among the 252 occupants.