Rolls-Royce has concluded that a component failure in the turbine section of a Trent 900 engine fitted to a Qantas Airbus A380 led to the oil fire which destroyed the powerplant in-flight.
In an update to the investigation today the manufacturer states that the failure was "confined to a specific component" in the turbine area.
It has not detailed the nature of the component but reiterates that the problem is specific to the Trent 900 powerplant, which is fitted to 20 of the 37 A380s in operation worldwide.
Rolls-Royce says that the failure caused an oil fire and the subsequent loss of the intermediate-pressure turbine disc.
The 4 November incident wrecked the rear half of the engine and caused damage to the surrounding airframe structure - the extent of which has yet to be fully disclosed. The Qantas aircraft landed safely in Singapore.
"Our process of inspection will continue and will be supplemented by the replacement of the relevant module according to an agreed programme," says Rolls-Royce.
"These measures, undertaken in collaboration with Airbus, our Trent 900 customers and the regulators have regrettably led to some reduction in aircraft availability.
"This programme will enable our customers progressively to bring the whole fleet back into service."
In a financial update today Rolls-Royce admits that underlying profit growth for the full year will be "slightly lower" than previously forecast as a result of the Trent 900 incident.
Chief executive Sir John Rose says: "This event and the consequent actions will have an impact on the group's financial performance this year."
All three operators of Trent-powered A380s - Qantas, Singapore Airlines and Lufthansa - have undertaken engine changes, for various reasons, since the incident. Qantas' A380 fleet remains grounded.