The Federal Aviation Administration is investigating another incident with a Boeing aircraft after a Southwest Airlines flight lost its engine cover during takeoff on Sunday.

Southwest Airlines Flight 3695 was en route to Houston when its engine cowling came off and struck the wing flap around 8:15 a.m., forcing the flight to return to its origin point at Denver International Airport, according to the FAA.

In footage obtained by ABC13 Houston , passengers watched as the force of takeoff appeared to strip the metal coverings off the planes engine parts, leaving the pieces to flap in the wind before snapping off and flying away.

Lisa C., the passenger who shot the video, told ABC News she noticed that the engine cowling peeled off within the first 10 minutes of the flight.

We all felt kind of a bump, a jolt, and I looked out the window because I love window seats, and there it was, she explained.

In a statement, Southwest said the Boeing 737-800 aircraft landed safely after experiencing a mechanical issue and that its maintenance teams were inspecting the aircraft.

Aircraft manufacturer Boeing has been under heavy scrutiny since the door plug of a Boeing 737 Max 9 was ripped from a plane mid-flight in January.

The incident led the FAA to ground 171 Boeing 737 Max 9s across the nation.

Sundays mechanical issue involved an older model of Boeing 737. According to FAA records reviewed by CNN , the aircraft was first deemed airworthy in May 2015.