The ATSB has found that an engine shutdown aboard an Emirates A380 departing Sydney on November 11 2012 was the result of significant internal damage that had initiated within the high-pressure turbine (HPT) module.
The aircraft, A6-EDA, was climbing through 9,000ft when the crew reported hearing a loud bang accompanied by a No 3 engine exhaust gas temperature over-limit warning. Shortly thereafter, the engine went through an uncommanded shut down. The crew jettisoned excess fuel and returned the aircraft to Sydney for a safe landing and disembarkation of the passengers and crew.
The investigation found the damage had resulted from the effects of HPT stage-2 nozzle distress, likely caused by exposure to hotter than expected operating temperatures. The nozzle distress led to eventual failure and separation into the gas flowpath.
During the inbound flight, the engine health and trend monitoring program had identified a performance trend shift with this particular engine, and it was due to be inspected upon return to the main base in Dubai.
During the weeks preceding this event Emirates had experienced two similar incidents in its fleet. The airline said a number of steps had been taken by the manufacturer, Engine Alliance, to address the issue, including the increased monitoring of distress development. Engine Alliance had earlier issued service bulletins for the replacement of affected HPT stage-2 nozzle segments with new, more durable components