What happened
During the takeoff and initial climb phase of flight, the aircraft sustained a contained failure within the left engine turbine section. This mechanical failure was accompanied by a tail pipe fire. The flightcrew subsequently returned to the airport and performed a successful landing.
After stopping on the runway, an evacuation was initiated. The flight deck crew issued the evacuation command and specifically instructed flight attendants to use the right side exits only. During the emergency, the crew of Flight 230 attempted to communicate with airport rescue services, asking the tower how to correspond with the ground vehicles regarding the status of the left engine. The controller directed the crew to the ground control frequency. A review of communication transcripts later showed that the crew had difficulty establishing radio contact with the airport's Crash Fire Rescue (CFR) vehicles.
The investigation
A post-incident teardown of the engine revealed significant damage to the turbine blades from stage 1 through stage 4. Investigators found that the outer buttress aft flow guide, also known as an "angel wing," was completely missing from the 1st stage nozzle guide vane (NGV). The damage observed on the 1T blade was consistent with damage caused by the liberation of this hardware, although investigators could not determine the initial mode of the fracture.