The National Transportation Safety Board has released its preliminary report on the March 13 incident involving American flight 1006, finding multiple engine component failures that led to engine vibrations, an emergency landing, and a post-landing fire.

Incident Description

According to the NTSB report, the Boeing 737-800, registered as N885NN, experienced engine vibrations during takeoff from Colorado Springs Airport. The flight crew continued the takeoff and diverted to Denver.

After the plane landed and taxied to the gate, a fire broke out in the right engine area after both engines were shut down.

Airport surveillance footage captured a fluid trail leaking from under the right engine nacelle as the aircraft taxied to the gate. The fire was extinguished within one minute by gate ramp personnel before airport firefighters arrived.

Of the 178 people aboard – including 172 passengers, two flight crew, and four cabin crew – 12 passengers sustained minor injuries during the evacuation.

The aircraft had “substantial damage,” investigators said, primarily affecting the right engine nacelle, wing, and fuselage.

Initial Findings

NTSB investigators discovered multiple technical issues with the right engine, a CFM56. Their examination revealed:

• One fractured fan blade platform.
• A fuel fitting lockwire on the variable stator vane that was loose and incorrectly installed.
• An incorrectly fastened VSV actuator rod end, which allowed fuel to leak from the fitting.
• A fractured VSV rod end muscle line in the weld.
• A blocked seal drain line in the inboard thrust reverser half, with sealant obstructing the lower bifurcation fire seal and exit tube.

Evacuation Challenges

The investigation revealed several issues during the emergency evacuation:

• The L2 door was found “cracked open” with its escape slide jammed in the door, preventing operation.
• The R2 evacuation slide deployed automatically when that door was opened.
• Passengers who used the left overwing window exits evacuated using a combination of ground vehicles, ladders, and a belt loader.
• The aircraft’s flaps remained at zero degrees during the evacuation, complicating the exit from overwing positions.

The L2 slide, which was found removed from its bustle and on the cabin floor with its safety pin installed, was sent to the manufacturer for detailed inspection.

According to investigators, “Soon after arriving at the gate, flight attendants heard passengers yelling ‘fire’ and ‘smoke’ and saw smoke start to fill the cabin. One of the flight attendants tried calling the flight crew but did not get an answer. Another flight attendant knocked on the cockpit door to alert the flight crew of the fire outside the airplane and smoke in the cabin.”

Flight attendants later initiated an evacuation.

The aircraft remains out of service at the time of writing. The agency says its investigation into the incident will continue.