Southwest Airlines is expecting to cancel more flights each day this week as it continues to carry out its inspection programme on CFM56-7B engines following last week’s events.
The US carrier cancelled more than 40 flights on Sunday, equating to approximately 1% of those scheduled, and says it expects that between 1-2% of its flights will be affected over the coming days. Over the next 30 days it is carrying out inspections of the engines manufactured by CFM International, a decision it took almost immediately after the incident, which lead to one passenger fatality onboard Flight 1380 after a fan blade broke off and fragments entered the fuselage of the B737-700.
The US Federal Aviation Administration and European airline regulators on Friday ordered emergency inspections within 20 days of nearly 700 of the aircraft engine type.
Southwest stated: “We have minimised flight disruptions this past week through actions such as proactive aircraft routings to cover open trips, performing inspections overnight, and utilising spare aircraft, when available. On Sunday, we only cancelled about 40 flights due to fan blade inspections out of a planned schedule of almost 4,000 flights.” It added it anticipates “minimal delays or cancellations each day this week due to the inspections.”
The carrier added its cancellations were the result of a “voluntary, accelerated engine fan blade inspection programme,” rather than the inspections ordered by the US and European aviation authorities. It is carrying out the inspections on its B737-700s and B737-800s.
CFM service bulletin
CFM International, the 50/50 joint venture company between GE and Safran Aircraft Engines, issued a service bulletin on Friday to operators of CFM56-7B engines, which power the Boeing Next-Generation 737. It recommends ultrasonic inspections within the next 20 days to fan blades of CFM56-7B engines with more than 30,000 cycles since new.
It also 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 added.
Around 680 engines will be impacted by the order to inspect engines with more than 30,000 cycles within the next 20 days. More than 150 of those have already been checked by operators. Approximately another 2,500 engines will be impacted by the recommendation to inspect fan blades with 20,000 cycles by the end of August. The on-wing inspection, conducted with an ultrasonic probe along the surface of the fan blade, takes about four hours per engine.
Around 14,000 CFM56-7B engines are currently in operation, with approximately 60 customers worldwide operating engines within the cyclic thresholds covered by the service bulletin. CFM also added that, with its partners GE and Safran Aircraft Engines, it has about 500 technicians directly involved to support customers and minimise operational disruption.
