A Qatar Airways Boeing 787-8, registration A7-BCH performing flight QR-24 from Manchester, EN (UK) to Doha (Qatar), was enroute at FL390 about 180nm northwest of Vienna (Austria) in Czech Airspace when the crew received a left hand engine (GEnx) fire indication, worked the related checklists while drifting the aircraft down to FL240 and decided to divert to Vienna where the aircraft landed safely on runway 29 about 50 minutes after leaving FL390. Emergency services did not find any evidence of fire.
Maintenance found the engine cowl was discoloured on the inner side, however, no soot or other evidence of a fire suggesting that hot gasses exited the engine at a location where they were not supposed to occur. The engine needed to be replaced.
The aircraft was on the ground in Vienna for 5 days before returning to Doha as QR3252