A Southwest Airlines Boeing 737-800 lost a part of its engine cover while taking off from Denver International Airport in Colorado on Sunday, according to officials and passengers. No one was injured. The incident happened on Sunday morning when Southwest Airlines Flight 3695 was taking off from Denver for a scheduled flight to Houston. Footage shared by passengers showed parts of the engine cover coming off. “Let’s go ahead and declare an emergency for Southwest 3695 and we’d like an immediate return,” the pilot told air traffic control. “We’ve got a piece of the engine cowling hanging off, a…