The Federal Aviation Administration (FAA) has 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 on Friday and on information gathered from the investigation of Tuesday’s Southwest Airlines engine failure. A passenger was killed in the accident.

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 is effective immediately.

Engine inspections

CFM’s statement explains: “CFM recommends ultrasonic inspections within the next 20 days to fan blades of CFM56-7B engines with more than 30,000 cycles since new.  Also, it recommends inspections by the end of August for fan blades with 20,000 cycles, and inspections to all other fan blades when they reach 20,000 cycles.

“After first inspection, operators are recommended to repeat the inspection every 3,000 cycles, which typically represents about two years in airline service.”

It adds: “A jet engine cycle comprises an engine start, takeoff and landing, and full shut down.  An engine cycle is an important measurement in determining the maintenance and inspection intervals for jet engines and their components.”

Impact

Approximately 14,000 CFM56-7B engines are in operation.  The fan-blade inspections recommended within the next 20 days for engines with more than 30,000 cycles will impact about 680 engines.  More than 150 have already been inspected by operators.  Inspections recommended by the end of August for fan blades with 20,000 cycles will impact an additional 2,500 engines.

The inspection, conducted on-wing with an ultrasonic probe along the surface of the fan blade, takes about four hours per engine. 

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