The Federal Aviation Administration (FAA) issued an Emergency Airworthiness Directive (EAD) that requires operators to inspect fan blades on certain CFM56-7B engines within 20 days.
The directive is based on a CFM International Service Bulletin issued today and on information gathered from the investigation of Tuesday’s Southwest Airlines engine failure. The inspection requirement applies to CFM56-7B engines.
Specifically, engines with more than 30,000 total cycles from new must complete inspections within 20 days. The EAD becomes effective upon publication. The engine manufacturer estimates today’s corrective action affects 352 engines in the U.S. and 681 engines worldwide.
The engine fan blades are used on Boeing 737-600, 700, 800 and 900 jets.
The USA National Transportation Safety Board (NTSB) believes one of the blades snapped on the Southwest flight 1380 on Tuesday 17 April 2018, flying at about 30,000 feet, hurling debris that broke a window. The incident killed one passenger who was sucked part way out of the plane and injured seven others. The plane, a Boeing 737 bound from New York to Dallas with 149 people aboard, made an emergency landing in Philadelphia.
NTSB investigators said one of the engine’s fan blades broke off from the hub during the flight. The broken edge of the blade showed crack lines consistent with metal fatigue.
NTSB QUESTION: Why didn’t the ring do its job?
NTSB investigators are taking the Southwest engine apart to understand what happened and will look at maintenance records for the engine. There’s a ring around the engine that’s meant to contain the engine pieces when this happens, and in this case it didn’t, which is the big focal point for the NTSB.
Engine failures occur from time to time as engines are being pushed to produce as much power as possible, many expert believe engines are right on the edge, and consequently sometimes engines fail, and that’s why the containment ring is there.
The engine failure was reminiscent of a similar event on a Southwest Boeing 737-700 jet in August 2016 as it flew from New Orleans to Orlando, Florida. Shrapnel from the engine left a 5-by-16-inch hole just above the wing. Passenger oxygen masks dropped from the ceiling. Pilots landed the plane safely in Pensacola, Florida.
Reported by the USA Federal Aviation Administration (FAA) and National Transportation Safety Board (NTSB).