A Southwest Airlines jet sits on the runway at Philadelphia International Airport after it was forced to land with an engine failure, in Philadelphia, Pennsylvania, on April 17, 2018. A catastrophic engine failure on a Southwest Airlines flight from New York to Dallas killed one person and forced an emergency landing in Philadelphia on Tuesday in a terrifying ordeal for passengers. / AFP PHOTO / DOMINICK REUTER

MIAMI — Almost all Boeing 737s in operation globally, powered by CFM 56-7B, will need engine inspections as required by European and U.S. regulators following yesterday’s Southwest Flight 1380 incident.

However, several Boeing 737 customers, like Korean Air Lines and Japan Airlines, already said on Wednesday that they were inspecting the engines of their planes.

“There need to be proper inspection mechanisms in place to check for this before there’s a catastrophic event, said Robert Sumwalt, Chairman of the U.S. National Transportation Safety Board (NTSB), on Tuesday.

“We are very concerned,” Sumwalt added. He said the NTSB will review if the engine type might have been subject to the directive, which is not yet finalized. The FAA proposal estimated that the tests would require two hours of labor per inspection.

READ MORE: Dreamliners Grounded by Virgin Atlantic, Air New Zealand: Engine Woes

Also, France’s BEA Accident Investigation Agency is sending experts to assist a U.S. research into the fatal incident, a BEA spokesman told Reuters. He also added that Safran, whose shares edged down 0.1% on Wednesday, is also dispatching technical advisers.

Southwest Airlines’ Flight 1380, operating New York–Dallas, suffered on Tuesday an uncontained engine failure. One of 144 passengers died. CFM International produced the engine involved in the incident; the engine is one of the most common used on Boeing 737s.

READ MORE: Southwest Airlines Flight 1380 Suffers Uncontained Engine Failure

The airline said it is speeding up inspections of all related engines and are expected to be completed within 30 days. Also, Korean Air said it has the same plans with its 737 fleet—about 20% to 30% of its 35 Boeing 737 use the same type of engine that caused Southwest incident, ending their inspections in November.

Likewise, a Japan Airlines’ spokesman said that the CFM 56-7B engine powers two 737s in its fleet and inspections were due to be completed by the end of Wednesday.

Another airline, Qantas Airways, which is a large 737 operator, said its engines were of a slightly different model than those targeted for preventive checks.

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In August 2016, a Southwest flight made a safe emergency landing in Pensacola, Florida, after a fan blade separated from the CFM 56-7B engine. Investigators found signs of metal fatigue. The incident prompted the U.S. Federal Aviation Administration (FAA) to propose ultrasonic inspections of similar fan blades and their replacement.