We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-600, -700, -700C, -800, and -900 series airplanes. This proposed AD was prompted by a report of cracks found in the skin at body station (STA) 540 just below stringer S-22L on a Model 737-700 series airplane. This proposed AD would require 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. We are proposing this AD to detect and correct fatigue cracking in the skin, which can result in rapid decompression of the cabin.
Agency Contact: Alan Pohl, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: 425-917-6450; fax: 425-917-6590; email: firstname.lastname@example.org.
This is a proposed regulation. Comments were due on September 10, 2012.