On August 27, 2016, Southwest Airlines Flight 3472 was climbing over the Gulf of Mexico when a routine flight suddenly turned into a frightening emergency at 31,000 feet. The Boeing 737-700 was only about 12 minutes into its journey from New Orleans to Orlando when its left engine suffered a catastrophic failure.
What made the incident particularly alarming was that the engine did not simply stop working. Parts of it broke apart, the engine inlet separated from the aircraft, and debris struck the fuselage, creating a hole and causing the cabin to lose pressure.
Despite the spectacular damage, all 104 people aboard survived without injury.
The aircraft, registration N766SW, was a Boeing 737-7H4 that had been delivered to Southwest Airlines in 2000. It was carrying 99 passengers and five crewmembers and had departed Louis Armstrong New Orleans International Airport bound for Orlando International Airport. The aircraft was climbing through flight level 310, approximately 31,000 feet, when the left CFM56-7B engine failed.
The failure began inside the engine with fan blade No. 23. Investigators later determined that the blade had developed a low-cycle fatigue crack in its dovetail, the portion of the blade root that fits into the fan disk. The crack eventually caused the blade to separate from the fan disk while the engine was operating at high speed.
The separated blade then struck the engine’s fan case. The impact caused the blade to break into additional fragments, which traveled forward into the engine inlet. The resulting damage was considerably more extensive than investigators initially expected from the certification testing performed for this type of engine.
The chain of damage continued rapidly. The structural integrity of the engine inlet was compromised, and portions of the inlet separated from the aircraft while it was flying at altitude. Some of those pieces struck the left side of the Boeing 737.
One of the most disturbing discoveries came when investigators examined the fuselage. A hole measuring approximately 5 inches by 16 inches had been created in the left side of the aircraft just above the left wing…
