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“Undetectable” Defect Blamed For Engine Failure   MARY GRADY     An internal defect caused an uncontained engine failure, leading to a fire, during the takeoff roll of a Boeing 767 in October 2016, the NTSB said in its probable-cause hearing on Tuesday. The subsurface defect led to cracking in a turbine disk. The cracks were undetectable using current inspection methods, the investigators found. “Even though there have been significant advances in the safety performance of passenger airplanes over the last few decades, this accident shows there are still improvements that can be made,” said NTSB chairman Robert Sumwalt. “Current inspection methods – those that can fail to uncover a defect in a safety-critical component of an airliner – need a closer look.” The American Airlines flight, bound for Miami, was on its takeoff roll at Chicago O’Hare International Airport when a turbine disk in the right engine failed, sending metal fragments through a fuel tank and wing structure. Leaking fuel fed a fire. The flight crew aborted the takeoff and stopped the airplane on the runway. All passengers and crew evacuated and survived. One passenger was seriously injured after encountering jet blast from the good engine, which was still running. The NTSB found several problems with the evacuation procedures, including a lack of communication between the flight crew and cabin crew. The airplane was damaged beyond repair. The NTSB made one recommendation to American Airlines, one to Boeing, and seven new recommendations to the FAA. The NTSB also reiterated two recommendations to the FAA on emergency evacuations because that agency has yet to favorably act upon them. The complete accident report will be available in a few weeks. The findings, probable cause and safety recommendations, as well as Sumwalt’s prepared remarks and the PowerPoint presentations given on Tuesday, are all available online.