KUALA LUMPUR (Aug 23): The Australian Transport Safety Bureau (ATSB) said AirAsia X Bhd's Airbus A300 engine malfunction on June 25 this year, could be due to "metal fatigue" that originated within the blade’s internal structure. 

In a statement today, the ATSB said the engine manufacturer found that a section of the fan blade was separated at about one quarter of its length, from the blade base. The ATSB said the Airbus A300's registration number was 9M-XXE.

"The aircraft had earlier departed Perth, Western Australia, bound for Kuala Lumpur, Malaysia. While conducting a climb from flight level (FL) 380 (38,000 ft) to FL 400 (40,000 ft), a fan blade on the number 1 engine failed, resulting in engine damage and significant airframe vibration.

"Interviews and analysis of recorded flight data indicated that the flight crew conducted an in-flight engine shutdown and returned to Perth. The shutdown engine continued to rotate in the airflow, resulting in ongoing airframe vibration. The aircraft returned to Perth and landed safely," the ATSB said.

The bureau said investigation and analysis of the fan blade failure mode, were ongoing.

The statement said findings of the engine manufacturer would be included in ATSB’s draft safety investigation report. The draft report will be provided to relevant parties for comment, before the completion and release of the final report.

AirAsia X had not issued a statement in response to ATSB's statement at the time of writing.