The Federal Aviation Administration (FAA) has issued a final rule airworthiness directive (AD) for the CFM International CF56 engine, addressing an unsafe condition that led to two engine failures, including a fatal incident involving a Southwest Airlines Boeing 737-700 aircraft.
On March 4, the FAA issued an AD affecting all Boeing 737 NG family aircraft-- the 737-600, 737-700, 737-700C, 737-800, 737-900, and 737-900ER. This action was prompted by two engine fan blade-out (FBO) events aimed at rectifying the unsafe condition.
The FBO events resulted in the separation of CFM56 inlet cowl and fan cowl parts from the aircraft. In one case, these parts damaged the fuselage, caused loss of pressurization, and forced an emergency descent.