An engine shutdown that forced a Brisbane-bound Qantas flight to make an emergency landing in Sydney was likely caused by a mechanical failure of the high-pressure turbine.

Qantas flight QF520 from Sydney to Brisbane suffered a contained engine failure while taking off from Sydney Airport on November 8, forcing it to return.

The Boeing 737-800 managed to complete the take-off with just a single working engine, and resulted in a grassfire near Sydney Airport's third runway.

In a statement, Qantas chief pilot Dick Tobiano said preliminary investigations had found the shutdown was likely caused by a mechanical failure of the high-pressure turbine. 

He said the CFM56 engine has accumulated more than one billion flight hours globally, and that Qantas's rate of failures was consistent with world fleet failures for engines of similar age and operating environments. 

The CFM56 engine is manufactured by aerospace company CFM International and powers more than 600 airline operators worldwide, according to the company's website.

Mr Tobiano said the airline had removed two other Boeing 737 CFM56 engines from their fleet ahead of their scheduled replacement in the "next few months".

"This action was not because of an identified common fault, but a considered response to provide further buffers against regulated replacement limits," Mr Tobiano said.

"Together with CFM, Qantas Engineering continues to monitor all engines across our fleet in real-time with regular inspections."

The airline also confirmed the aircraft involved in the Sydney Airport incident had since returned to service.

"While in-flight engine shutdowns are rare, we know that airplane design, certification standards and flight crew experience and training come together to ensure safe outcomes," Mr Tobiano said.

The Australian Transport Safety Bureau has began a transport safety investigation into the engine failure incident.