CFM International, the 50/50 joint company between GE and Safran Aircraft Engines, has issued a new service bulletin today to operators of CFM56-7B engines, which power the Boeing Next-Generation 737. It calls for inspections of fan blades on long-service engines.
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.
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.
CFM issued this latest service bulletin after close coordination with the Federal Aviation Administration, European Aviation Safety Agency, Boeing, and CFM56-7B operators worldwide.
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. However, 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.
The CFM56-7B engine first entered service on the Boeing 737 in 1997 and has long been a workhorse of the airline industry. The engine fleet has accumulated more than 350 million flight hours.
About 60 customers worldwide operate engines within the cyclic thresholds of the new service bulletin. CFM partners GE and Safran Aircraft Engines have about 500 technicians directly involved to support customers and minimize operational disruption.