The FAA has issued an airworthiness directive for the Boeing 737-600, -700, -700C, -800, and -900 series. The AD was prompted by a report of cracks found in the skin at body station 540 just below stringer S-22L on a 737-700. The AD requires repetitive detailed and high-frequency eddy current inspections for cracking of the skin around the eight fasteners common to the ends of the STA 540 bulkhead chords between stringers S-22 and S-23, left and right sides; and corrective actions and preventive modification if necessary. The FAA is issuing this AD to detect and correct fatigue cracking in the skin, which can result in rapid decompression of the cabin.