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Fan blade flaws continue to plague airlines
October 19, 2018
Source: ASM International
More flaws in jet engine fan blades, like one that cracked and broke loose in April, killing a Southwest Airlines Co. passenger, have been discovered on planes operated by several carriers, and the manufacturer is moving to further tighten inspections.
General Electric Co., part of a venture that makes the engines, found a cracked blade during post-accident inspections of another Southwest plane, and spotted four or five more in those of other airlines, Southwest COO Michael Van de Ven said.
“We expect to formalize the interval in a new service bulletin that will be issued in coming days,” GE spokesman Perry Bradley said in a statement. Service bulletins are non-binding recommendations on maintenance, but are almost always made mandatory by aviation regulators.
Southwest has already cut the inspection interval for older engines almost in half, from 3,000 flights to 1,600, CEO Gary Kelly said in an interview. The Federal Aviation Administration said in a statement that it is working with airlines and the engine maker. “As we receive more inspection results we may adjust the compliance time accordingly,” the agency said.
After the April 17 incident, in which a cracked blade broke off and sent debris into a window on a Southwest flight, the FAA issued a series of orders for carriers to look for cracks on all older CFM56-7B engines. The agency first required inspections on those with more than 30,000 flights, then lowered it to 20,000 flights. After that milestone, engines have to be inspected within 3,000 flights, the agency ordered in May.
The engine is made by CFM International Inc., a joint venture between General Electric Co. and France's Safran SA. GE determined that more frequent lubrication of the blades potentially could help avoid damage, Van de Ven said.
The tighter inspection process shouldn’t cause any airline disruptions, GE’s Bradley said. Almost all of the 14,500 CFM56-7B engines in service around the world have received their initial inspections and were cleared, he said.
GE could not comment in greater detail because the failure is under investigation by the National Transportation Safety Board (NTSB), he said. He would not confirm the number of cracks found on other blades, saying only “there have been a handful of findings as a result of the inspections.”
The NTSB said that it will hold an investigative hearing on the engine’s failure, a signal the agency is giving the incident a high priority.
Image – A member of the Southwest Airlines’ technical operations team performs detailed ultrasonic inspections of engine blades. Courtesy of Southwest Airlines.
For more information:
Story posted by ASM earlier this year about the April 17th metal fatigue-related crash of a Southwest flight:
Materials Properties and Performance | Fatigue
Materials Properties and Performance | Fracture
Materials Testing and Evaluation | Failure Analysis
Materials Testing and Evaluation | Metallography and Microstructures
Materials Testing and Evaluation | Nondestructive Testing
Metals and Alloys | Titanium