Days after an older Boeing 737 engine caught on fire, there's still few answers about what led to the sparks. But aviation experts are keyed in to reports of "engine vibrations."

An American Airlines flight from Colorado Springs to Dallas diverted to Denver after the FAA says the crew reported “engine vibrations.” Soon after landing, the engine caught on fire. In a harrowing scene,

An "engine-related issue" caused American Airlines Flight 1006 to catch fire after landing at Denver International Airport.