A US passenger plane has made an emergency landing after part of one of its engines came loose in mid-air.

Key points: Video shot by a passenger shows a plane part bouncing around in a turbine

Video shot by a passenger shows a plane part bouncing around in a turbine An aviation expert says the plane would have been able to fly with one inoperative engine

An aviation expert says the plane would have been able to fly with one inoperative engine After an emergency landing, the passengers were put on another aircraft

The Delta Air Lines flight was travelling from Atlanta to Baltimore on Monday (local time) when it was forced to land in Raleigh, North Carolina, roughly halfway through the one-and-a-half hour trip.

In a statement, a Delta spokesperson said the crew decided to divert the plane "after receiving an indication of an issue with one of the aircraft's engines".

Footage posted to social media by passenger Logan Webb shows one of the engine's nose cones, also known as a spinner, being tossed around a jet turbine.

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The video was shared by Twitter user @RAREsheis, who said she was also on the flight and heard a loud bang before being told "we lost an engine".

"Although it was a completely terrifying situation to see smoke in the cabin and smelling something burning for the first five mins, the crew did an amazing job in staying and keeping us all calm, while preparing us for an emergency landing," she said in a tweet.

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The 148 passengers later boarded another plane bound for Baltimore.

A Delta spokesperson said the aircraft's engine had been replaced and the airline's maintenance team had been tasked with examining the damaged part.

Aviation expert John Cox of Safety Operating Systems told Storyful it was "extraordinarily rare" for an engine to lose its spinner.

"I have been around this type of engine [a Pratt and Whitney JT-8] since 1980," Mr Cox said.

"I have never seen or heard of a spinner coming off."

He said those on the aircraft were not in danger "as all airliners can fly with one engine inoperative".

Pratt and Whitney describes its JT8D and JT8D200 series as the "most popular modern commercial engines ever made", powering nearly one third of the world's commercial planes.

"More than 14,000 of them have been built, amassing more than half a billion hours of reliable service since 1964," the company says.