The China Eastern aircraft was travelling to Shanghai when the damage was discovered
A passenger plane was forced to return to Sydney after an in-flight problem left it with a gaping hole in one of its engine casings.
China Eastern said the crew noticed damage to the air inlet on the left engine after takeoff on Sunday evening and the captain decided to return to Sydney.
On its Sina Weibo microblog, the airline said the Airbus A330 landed safely and it was looking after customers on board.
"The crew observed the abnormal situation of the left engine and decided to return to Sydney Airport immediately," a China Eastern spokeswoman told AFP.
"The returned aircraft is currently under investigation at Sydney Airport."
Passengers told Australian media they heard a massive noise and smelled something burning.
"We, like, went up in the air and all of a sudden, I heard like 'z-z-z-z-z' and it was really, really loud. It kind of smelled like burning," one passenger told Channel Seven.
"Oh, I was scared. Yes. I was really scared. Our group was terrified."
Images showed a vertical hole in the side of the engine.
The aircraft was travelling to Shanghai when the damage was discovered.
An investigation has been launched by the Australia Transport Safety Bureau.