Federal investigators say an American Airlines plane that caught fire in March had a cracked engine fan blade and a component installed backward, according to a preliminary report released Thursday by the National Transportation Safety Board (NTSB).

The March 13 incident involved American Airlines Flight 1006, which had been en route from Colorado Springs to Dallas before diverting to Denver due to engine vibrations.

After landing, a fluid trail was seen leaking from beneath the right engine as the aircraft taxied to its gate. Moments later, passengers began shouting “fire” and “smoke” as the cabin filled with smoke, prompting an emergency evacuation. One of the emergency slides failed to deploy correctly, jamming in the door. Passengers exited via a functional slide and the over-wing exits. No serious injuries were reported, though 12 passengers sustained minor injuries during evacuation.

The NTSB said the damaged fan blade and a mis installed lockwire on the variable stator vane — a part that regulates airflow inside the engine — were both located in the aircraft’s right engine. That engine was manufactured by CFM International, a joint venture between GE and France’s Safran SA. While American Airlines says it is cooperating with the investigation, GE declined to comment and Safran has not responded to media inquiries.

The report did not clarify when the faulty part was installed or last inspected.

"The way this is looking is that there was a maintenance issue that led to this fire and we've gotta figure out where that error occurred so we can keep that error from happening again," said former NTSB chair Robert Sumwalt, CBS News transportation safety analyst.

Commenting on the report, Sharon Petersen, CEO at AirlineRatings.com, said:

“This is a serious concern. When basic mechanical components are either failing or being installed incorrectly, it raises red flags about maintenance oversight and quality control — not just at the airline level, but across the supply chain. Thankfully no lives were lost, but this underscores how crucial meticulous engineering and inspection are to aviation safety.”

Video footage posted to social media shows several passengers standing on the plane’s wings as emergency crews arrived. The flight carried 172 passengers and six crew members.