To a qualified and well-equipped nondestructive testing technician, few inspections present an insurmountable technical hurdle. Technicians have a range of testing methods at their disposal, from sophisticated ultrasound and eddy current technologies to manual processes like liquid penetrant.

On April 20, three days after a Southwest Airlines Boeing 737-700 experienced an engine failure due to a fractured fan blade, resulting in the death of a passenger, the U.S. Federal Aviation Administration issued an emergency airworthiness directive that requires operators of CFM56-7B engines with more than 30,000 flight cycles to perform a one-time ultrasonic inspection of all 24 fan blades to detect cracking.