In the wake of an in-flight engine failure that killed a Southwest Airlines passenger, the carrier has started ultrasonic inspections covering virtually its entire fleet of more than 700 planes.
The Dallas-based carrier canceled 40 flights over the weekend and an additional 129 flights Monday as it moved to conduct the inspections of the fan blades on all of its CFM56 engines over the next 30 days, exceeding the requirement of a Federal Aviation Administration order last week.
The airline said that about 1% to 2% of flights would be disrupted over the next several days as it conducts inspections.
The accident took place when an engine fan blade fractured, sending shrapnel into the fuselage, killing Jennifer Riordan, a bank executive and mother of two from New Mexico. The flight from New York to Dallas made an emergency landing in Philadelphia. It was the first fatality of a passenger in Southwest's 51-year history and the first passenger to die on a U.S.-based carrier in nine years.
The FAA and CFM International, the manufacturer of the CFM56 engines, both called on Friday for ultrasonic inspections within 20 days of engines with at least 30,000 cycles — or takeoffs and landings. Such engines typically are about 20 years old and the FAA said its order would apply to 352 engines on planes flown in the United States and 681 engines flown worldwide by various carriers.
Southwest said it is meeting the FAA requirement and going further by inspecting all CFM56 engines, including those that have not reached the 30,000-cycle threshold.
The CFM56 engine is one of the most widely used jet engines for commercial use in the world, according to its manufacturer.
United Airlines operates 547 Boeing 737 planes with CFM engines, according to Boeing's website. About 400 of those planes were delivered to United at least 20 years ago, the website shows. United Airlines previously said it had already begun inspections of the engines, but a representative declined to elaborate Monday on the progress.
American Airlines operates 305 Boeing 737 planes that are powered by the CFM56 engines and all of those were delivered within the last 19 years, according to the Boeing website. Airline officials say that none of those American Airlines planes have yet experienced 30,000 cycles and therefore are not required to be inspected under the FAA directive.
Still, American Airlines officials said last week that they had already begun testing the fan blades on the CFM56 engines in response to a proposed inspection rule issued last year that was not finalized until Friday, after the accident.
Southwest said it will inspect all of the roughly 700 Boeing 737-700 and 737-800 model Southwest planes that are installed with CFM56 engines. Only about a dozen planes in the Southwest fleet will not need to be inspected because they don't use those types of CFM engines.
The ultrasonic inspections will focus on the fan blades because inspectors suspect the cause of the accident was metal fatigue, which cannot necessarily be detected visually. Southwest experienced a similar engine failure on the same model engine two years ago, forcing an emergency landing.
CFM International, a joint venture of GE and Safran Aircraft Engines of France, said the inspection is conducted with the engine on the wing and takes about four hours per engine. Southwest said it was doing what it could to prevent delays and cancellations.
"This week, we will continue working to minimize flight disruptions by performing inspections overnight while aircraft are not flying and utilizing spare aircraft during the day, when available," the airline said in a statement Monday. "We anticipate minimal delays or cancellations each day this week due to the inspections."
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4:10 p.m.: This article was updated to include information about additional Southwest flight cancellations and inspections of Boeing 737 planes operated by American Airlines and United Airlines.