Asia-Pacific airlines operate 2,316 Boeing 737s powered by CFM56-7B engines, but most of these aircraft are below the cycle threshold required by a new inspection protocol.

CFM International has recommended ultrasonic inspections on fan blades within the next 20 days for CFM56-7Bs with more than 30,000 cycles since delivery. For engines with 20,000 cycles or more, CFM recommends inspections by August. When engines hit 20,000 cycles, they should receive the inspection, which should be repeated every 3,000 cycles, representing roughly two years of service.

Flight Fleets Analyzer shows that Indonesia’s Sriwijaya Air is most exposed, with 26 aircraft powered by CFM56-7B engines in its fleet. While aircraft ages range from 3.1 to 19.8 years, the average aircraft age is 14 years, equating to an average cycle count of 21,000.

Following Sriwijaya are three South Korean low-cost carriers.

Eastar Jet has 18 CFM56-7B powered 737s with an age range of 5.6 to 20 years, and an average aircraft age of 13.2 years, equating to an average of 19,800 cycles. Jin Air has 20 examples with an average age of 12 years, equating to 18,000 cycles, and Jeju Air has 33 examples with an average age of 11.7 years, equating to 17,550 cycles.

Other Asia-Pacific carriers with large numbers of 737s powered by CFM56-7B engines with an average aircraft age of ten years or older are Air Do (nine aircraft), Korean Air (36), and Qantas (70).

The biggest operators of CFM56-7B powered 737s in the region are China Southern Airlines (180 aircraft), Hainan Airlines (155), Xiamen Airlines (149), Air China (134), and Shandong Airlines (115). The average age of this fleet is 5.7 years, equating to 8,550 cycles.

The service bulletin came three days after a fan blade blew out of a CFM56-7B engine with 40,000 cycles on a Boeing 737-700 operated by Southwest Airlines. Pieces of the engine or cowling penetrated the wing and fuselage, blowing out a window and killing one passenger.

About 680 engines are covered under the 30,000-cycle inspection deadline and 2,500 engines fall under the August deadline, says CFM, a joint company formed by GE Aviation and Safran. Following CFM's service bulletin, the US Federal Aviation Administration mandated a one-time inspection of about 680 CFM56-7B engines to check for cracks in the fan blade dovetail by 10 May.

Source: Cirium Dashboard