American Airlines Flight 383 Takeoff Aborted After Engine Failure (N345AN)

Incident Overview and Immediate Response On October 28, 2016, at approximately 1432 central daylight time, American Airlines flight 383, a Boeing 767-323 with registration N345AN, began its takeoff ground roll at Chicago O’Hare International Airport in Chicago, Illinois. During the roll, an uncontained failure occurred in the right engine, leading to a fire. The flight crew aborted the takeoff and brought the aircraft to a stop on the runway. Flight attendants then initiated an emergency evacuation. The aircraft was operating under 14 Code of Federal Regulations Part 121, and visual meteorological conditions were present at the time of the accident. ## Injuries and Damage The aircraft carried two flight crewmembers, seven flight attendants, and 161 passengers. During the evacuation, one passenger sustained a serious injury, while one flight attendant and 19 passengers received minor injuries. The aircraft sustained substantial damage from the fire. ## Technical Findings The uncontained engine failure was caused by a rupture of the high-pressure turbine (HPT) stage 2 disk. The disk initially separated into two fragments. One fragment penetrated the inboard section of the right wing, severed the main engine fuel feed line, breached the fuel tank, traveled up and over the fuselage, and landed approximately 2,935 feet away. The other fragment exited outboard of the right engine, struck the runway, and fractured into three pieces. Examination of the fracture surfaces in the forward bore region of the HPT stage 2 disk revealed dark gray subsurface material discontinuities with multiple cracks initiating along their edges. These cracks exhibited characteristics consistent with low-cycle fatigue, a condition in which cracks grow in single distinct increments during each flight. Additionally, a discrete region beneath the largest discontinuity appeared white compared with the surrounding material and contained microscopic-sized oxide particles, collectively referred to as a “discrete dirty white spot.” The National Transportation Safety Board (NTSB) determined that this anomaly was most likely not detectable during production inspections or subsequent in-service inspections using the procedures in place at the time. ## Evacuation and Contributing Factors The NTSB investigation found that the evacuation initially began while one engine was still operating. In accordance with company procedures and training, the flight crew performed memory items on the engine fire checklist, which included shutting down the engine on the affected side. The captain did not complete the remaining steps of the engine fire checklist, which applied only to airplanes in flight, and instead called for the evacuation checklist. The left engine was shut down as part of that checklist. However, flight attendants had already initiated the evacuation due to the severity of the fire on the right side of the aircraft, exercising their authority in a life-threatening situation. The NTSB identified that the serious passenger injury was contributed to by the delay in shutting down the left engine and a flight attendant’s deviation from company procedures, which resulted in passengers evacuating from the left overwing exit while the left engine was still operating. The delay in shutting down the left engine was contributed to by the lack of a separate checklist procedure for Boeing 767 airplanes specifically addressing engine fires on the ground and the lack of communication between the flight and cabin crews after the aircraft came to a stop.