On Thursday, May 3, 2018 the National Transportation Safety Board issued an update in connection with its ongoing investigation concerning the fatal mid-air Southwest Airlines Flight 1380 engine failure. The Investigative update can be found here.
The NTSB confirmed that as the aircraft was at Flight Level 32,000 feet, the Number 13 fan blade contained within the left engine broke off at its root causing significant damage to the engine inlet and cowling. These engine fragments then impacted the fuselage and left wing causing the window to break. As a result, the aircraft suffered a rapid decompression and tragically, one passenger suffered fatal injuries as she was swept into the open window by the violent force of air rushing out of the cabin. Eight other passengers suffered minor injuries. It is likely that all passengers suffered mental anguish and are experiencing post-traumatic stress symptoms due to this terrifying and horrific event.
The NTSB also released preliminary data that was captured on the aircraft’s Digital Flight Data Recorder. At an altitude of approximately 32,000 feet the parameters associated with the left engine all simultaneously dropped, and the aircraft began to significantly vibrate. Numerous alarms sounded in the cockpit and the aircraft experienced a rapid decompression. The aircraft rolled approximately 40 degrees to the left before the flight crew was able to gain control. Although the crew experienced handling difficulties during the descent, the Captain was able to successfully perform an emergency landing in Philadelphia.
The NTSB has conducted preliminary metallurgical testing on the failed left engine components. This examination determined that the Number 13 fan blade failed due to extensive fatigue cracking which was seen through ultrasonic inspection as well as inspections performed under a scanning electron microscope. The NTSB examined all remaining fan blades in the failed engine and none exhibited the fatigue cracking that caused the Number 13 blade to fail.
The fan blade that failed had accumulated approximately 32,000 flight cycles since new and more than 10,000 cycles since being overhauled in November 2012. The overhaul process did not subject the blade to an ultrasonic inspection to determine whether fatigue cracks were present. Rather, the process only required visual and fluorescent dye penetrant inspections which do not allow for microscopic fatigue cracks to be detected. As part of its investigation, the NTSB is attempting to determine the number of cycles at which fatigue cracks begin so that proper inspections are required to prevent this tragedy from reoccurring.
We expect that the NTSB will continue to release information as the investigation continues and we will continue to monitor the investigation. However, it is imperative that proper inspections uncover this deadly latent defect. Indeed, had ultrasonic inspections be required during the overhaul process it is possible that this tragedy would not have occurred. Such inspections are now required due to the 2016 engine failure mentioned in our prior post. Unfortunately, much more should have been done in the wake of the 2016 event to avert this horrible and senseless tragedy.