Summary
We propose to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 737-600 and -700 series airplanes. This proposed AD was prompted by reports of cracking in a bulkhead lower frame. This proposed AD would require a detailed and open hole high frequency eddy current (HFEC) inspection of the left- and right- side lower frame webs and inner chords for cracking, if necessary, and corrective actions and preventative modifications, if necessary. This proposed AD would also provide for optional terminating action for the repetitive inspections under certain conditions. We are proposing this AD to detect and correct cracking in a bulkhead lower frame web and inner chord, which could result in a severed frame and induced skin cracks, and lead to rapid decompression of the fuselage.