7 May 2018
Aerospace America reported that on Thursday, the NTSB said investigators examining the Southwest Airlines Boeing 737-700 which experienced a broken engine blade last month have found “six crack lines from metal fatigue in pieces of the blade discovered inside the CFM56-7B engine built by CFM International, the joint venture of Safran Aircraft Engines and GE Aviation.” The news comes as “aircraft technicians are in the process of sending ultrasonic waves through the fan blades of thousands of jet engines to check for metal fatigue.” The FAA and CFM have issued instructions for completing the jet engine blade tests that state that during the tests, “engines will be kept on the wings,” and technicians “must remove and clean the 24 titanium fan blades from each engine.” The investigators will examine blades “for cracks or flaws with their eyes before covering the blades with glycerin, a gel, that transmits the sound from an ultrasound probe to the surface of the blade.” If any irregularities are found on an engine fan blade, “such as a microscopic crack, this shows up on a handheld display as a peak in amplitude of the signal that echoed from the crack.” (Image Credit: Aerospace America)
More Info (Aerospace America)