Boeing plane engine cover falls off prompting investigation

US airline regulators have opened an investigation after an engine cowling on a Boeing 737-800 fell off during take-off and struck a wing flap.

The flight returned safely to Denver International Airport at about 08:15 local time after originally departing to Houston. 

The aircraft had 135 passengers and six crew members on board and had risen to around 10,300 feet before landing. 

It comes amid manufacturing and safety concerns at Boeing. 

The airline has said its maintenance teams would review the plane after its cowling, which covers the plane’s engine, fell off. The airline confirmed it was responsible for the maintenance of such parts. 

“We apologise for the inconvenience of their delay, but place our highest priority on ultimate safety for our customers and employees,” a statement said.

The plane was manufactured in 2015 according to regulator Federal Aviation Administration (FAA) records, and the 737-800 is an earlier generation of the 737 from the latest Max model.

Boeing has faced serious scrutiny after a dramatic mid-air blowout in January, in which passengers narrowly escaped serious injury.