Video taken by a passenger through the plane's window shows the plane taxiing to take off from Denver International Airport in Colorado on the morning of April 7 when the blue casing on the plane's engine peeled off and floated before being torn into small pieces, revealing the silver interior.

Boeing engine casing ripped off as plane prepares to take off

The peeling skin hit the plane's flaps. The US Federal Aviation Administration (FAA) said the plane had to make an emergency landing and returned safely to the airport at around 8:15 a.m., after the crew discovered the problem.

Another passenger Cooper Glass described the experience as “terrifying.” “People in the row across from me were screaming at the flight attendants and pointing out what was happening,” Glass said, praising the pilots for landing the plane safely.

Southwest Airlines said the plane "experienced a technical issue" and passengers were transferred to another plane to arrive at William P. Hobby Airport in Houston, Texas, three hours behind schedule.

"Our maintenance team is assessing the aircraft," the airline said.

The FAA will investigate the incident. According to FAA data, the plane was delivered to Southwest Airlines in 2015. The engine cover is typically made of aluminum alloy, is removable, and is often removed for maintenance.

Huyen Le (According to Hill , CNN , ABC )