- The National Transportation Safety Board said earlier this week that the fan blade separated in two places, and that the NTSB has evidence of a "fatigue fracture."
- The engine's maker is a joint venture of General Electric and France's Safran.
- The FAA is expected to make more rigorous inspections mandatory.
The manufacturer of the type of engine that exploded during a Southwest Airlines flight earlier this week, killing a passenger, called for more stringent testing of the engine's fan blades within three weeks, it said Friday.
CFM International, a joint venture of General Electric and France's Safran Aircraft Engines, built the CFM56-7B engine, which lost one of its fan blades on Southwest Flight 1380 shortly into a New York to Dallas trip on Tuesday morning. Shrapnel flew, puncturing the fuselage. One of the plane's windows blew out and a passenger, who died, was partly sucked out through the opening. The pilot made an emergency landing in Philadelphia.
"CFM recommends ultrasonic inspections within the next 20 days to fan blades of CFM56-7B engines with more than 30,000 cycles," the manufacturer said in an updated service bulletin.
"After first inspection, operators are recommended to repeat the inspection every 3,000 cycles, which typically represents about two years in airline service."
Service bulletins are only recommendations but the Federal Aviation Administration is expected to mandate more rigorous inspections of these commonly used engines. CFM said it issued the latest bulletin in "close coordination" with airline regulators in the U.S. and Europe, and with Boeing and airlines. The engine is used on Boeing's 737, its best-selling aircraft.
Fan blade inspectors often use ultrasonic testing because fractures can be too small to see with the naked eye.
CFM International recommended more stringent checks of the engines last year after a fan blade on the same type of engine broke during a Southwest flight in 2016. There were no fatalities on that flight, but flying debris punctured the aircraft. The FAA made its own proposal for more testing last year but the rule wasn't finalized.
Updated guidance from CFM International was set to be issued even before Southwest Flight 1380 earlier this week, a source familiar with the matter said.
More than a few thousand engines could be subject to the ultrasonic fan blade tests, according to the source.
Some airlines have recently ramped up testing of these engines.
After Tuesday's fatal explosion, Southwest said it would speed up tests of these engines and complete the task within 30 days.
On an earnings call this week, United Airlines executives said CFM56-7B engine tests are underway in response to guidance from the manufacturer. CEO Oscar Munoz said the tests are included in the airline's cost forecast. The airline has 698 of the engines in its fleet, according to its chief operations officer.
American Airlines, the world's largest carrier, said it "voluntarily" started inspections of its CFM56-7B engines, which power 304 of its Boeing 737-800s, when the FAA proposed more stringent testing last summer.