SYDNEY — A passenger jet was forced to turn back after an in-flight problem left a gaping hole in the engine casing.

China Eastern said the crew on Flight 736 noticed damage to the air inlet on the left engine after takeoff Sunday evening and the captain decided to return to Sydney, Australia.

The A330 plane from Airbus has two engines.

Australian media quoted passengers as saying they heard a loud noise and smelled something burning before the crew started moving everyone from the left side of the plane.

One passenger, who was identified only as Eva, said the cabin crew tried to calm passengers and told them to fasten their seatbelts after a noise was heard.

"We were very panicked because we had no idea what was happening," she told Channel 9 television.

The aircraft landed without incident and there were no injuries, according to Kathy Zhang, a general manager at China Eastern Airlines.

"It could have begun from loose screws"

The plane was bound for Shanghai, China.

Professor Jason Middleton, an aviation expert at the University of New South Wales in Sydney, said it appeared that the engine cowling had been ripped away forward of the main compressor blade.

"When one of these things happens you often don't know how the damage began. It could have begun from loose screws," he told the Australian Broadcasting Corp.

A spokeswoman for Rolls-Royce, which manufactured the plane's Trent 700 series engines, said in a statement: "We are aware of the incident and will be working closely with our customer and relevant partners to understand the cause of the issue."

The Australia Transport Safety Bureau confirmed it was investigating the incident.

— Reuters