Boeing plane's engine cover falls off, prompting investigation

US aviation regulators have launched an investigation after the engine cowl of a Boeing 737-800 fell off during takeoff and struck the wing flap.

The Southwest Airlines flight originally departed for Houston and safely returned to Denver International Airport at around 08:15 local time (15:15 Japan time).

The plane had 135 passengers and six crew members on board and climbed to approximately 10,300 feet (3,140 meters) before landing.

The incident comes amid concerns over Boeing's manufacturing and safety.

Southwest Airlines said its maintenance team will examine the Boeing 737-800 after a cowling covering the engine fell off. The airline acknowledged that it is responsible for maintaining such parts.

“We apologize for any inconvenience this delay may cause, but the ultimate safety of our customers and employees is our top priority,” the statement said.

Regulator Federal Aviation Administration (FAA) records show the plane was built in 2015, and the 737-800 is an older generation of the 737, the latest Max model.

Both aircraft are powered by CFM56 engines, a joint venture between General Electric Aerospace and Safran Aircraft Engines.

The FAA said the Boeing plane was towed to the gate after landing.

Boeing declined to comment when contacted by BBC News, referring questions about its aircraft and information about its operations to Southwest Airlines.

Southwest Airlines said it would fly passengers to Houston on a separate plane about three hours later than scheduled.

Boeing Co. has come under intense scrutiny following a dramatic mid-air explosion in January that narrowly escaped serious injury to passengers on a flight from Portland, Oregon, to California.

Regulators have temporarily grounded about 200 Boeing 737 Max 9 planes after a door plug fell off an Alaska Airlines plane shortly after takeoff.

Boeing has spent years trying to rebuild its reputation following crashes in 2018 and 2019 involving different versions of its 737 Max planes that killed 346 people.

The airline's popular 737 Max planes were subsequently grounded worldwide for more than 18 months.