Specialists from the General Electric and Pratt & Whitney Engine Alliance working with Australian investigators are focusing on a failed nozzle guide vane as the suspected cause of an engine shutdown on a GP7200-powered Emirates Airline Airbus A380.

The aircraft experienced the engine incident around 20 min. after departure from Sydney, Australia on Nov. 11. The aircraft, bound for Dubai with 380 passengers on board, returned safely to the airport, where inspectors are believed to have discovered damage caused by the failure of a second stage, high-pressure (HP) turbine nozzle guide vane.

Engine Alliance declines to comment specifically on the cause of the incident but says it “is investigating the root cause of the engine event and will initiate prompt corrective action.” It adds that, to date, the engine “has demonstrated excellent reliability and performance on the Airbus A380, and the Engine Alliance is committed to maintaining those standards.”

Emirates President Tim Clark in an interview with the Financial Times notes that several “rogue engines” also would be removed for fixing. The upgrade involves replacing the HP turbine second stage nozzle guide vanes with improved units with more advanced cooling.

The revised cooling configuration was designed after thermal distress in the guide vanes was unearthed during endurance runs of a test GP7200.

The change, prompted by an Engine Alliance-issued service bulletin in 2011, is thought to have been made to around 300 GP7200 engines, and fewer than a dozen are believed to still require the fix. One of these engines is also believed to be the unit involved in the Emirates event.