What happened
On August 27, 2016, Southwest Airlines Flight 3472 departed New Orleans International Airport bound for Orlando International Airport. The aircraft, identified by registration N854SW, was a Boeing 737-7H4 carrying 99 passengers and five crew members. Approximately twelve minutes into the flight, while climbing through an altitude of 31,000 feet over the Gulf of Mexico, the number one CFM International CFM56-7 engine suffered a catastrophic failure.
A fan blade within the engine fractured due to a fatigue crack. The detached portion continued to rotate inside the engine nacelle and struck the engine inlet structure. This impact generated debris that punctured the left side of the fuselage, leading to an immediate loss of cabin pressure. The force of the event also damaged the wing and empennage structures.
Following the failure, the crew deployed oxygen masks for the passengers and initiated an emergency descent to 10,000 feet. The aircraft diverted to Pensacola International Airport, where it landed safely approximately twenty minutes after the initial incident occurred.
Investigation
The investigation determined that the root cause of the engine failure was a fatigue crack in one of the fan blades. This structural defect allowed the blade to break under operational stress, leading to the uncontained separation of components within the engine. The subsequent damage to the aircraft structure was a direct result of debris from the damaged inlet striking the fuselage.
Findings
The primary contributing factor was the fatigue failure of the fan blade in the number one engine. Despite substantial damage to the aircraft, including the punctured fuselage and compromised wing and empennage sections, no injuries were reported among the passengers or crew. The emergency procedures executed by the flight crew allowed for a safe diversion and landing.