The Federal Aviation Administration said the "emergency" order was based on a service bulletin, also issued Friday from the engine's manufacturer, CFM International, calling for more stringent testing of the CFM56-7B engine, and an investigation into the deadly engine failure on Southwest Flight 1380, the airline regulator said. On May 2nd 2018 the FAA released another Airworthiness Directive 2018-09-10 that based on the same reasoning as the previously released EAD introduces a more generic inspection scheme requiring inspections of fan blades as follows:



(1) Perform an ultrasonic inspection (USI) or eddy current inspection (ECI) of the concave and convex sides of the fan blade dovetail as follows:



(i) Perform an initial inspection on each fan blade before the fan blade accumulates 20,000 cycles since new, or within 113 days from the effective date of this AD, whichever occurs later.
The United States Federal Aviation Administration issues an emergency Airworthiness Directive for CFM56-7B jet engines. The EAD expands on previous orders requiring ultrasonic testing to search for metal fatigue in fan blades. It mandates testing on engines that have reached 30,000+ flights, believed to cover 352 US engines and 681 engines worldwide.