Airworthiness Directives; The Boeing Company Airplanes

We propose to adopt a new airworthiness directive (AD) for all The Boeing Company Model 737-600, -700, -700C, -800, -900 and -900ER series airplanes. This proposed AD was prompted by an evaluation by the design approval holder (DAH) indicating that certain fastener locations in the window corner surround structure are subject to widespread fatigue damage (WFD). This proposed AD would require repetitive high frequency eddy current (HFEC) inspections for cracking in certain fastener locations in the window corner surround structure, and repair if necessary. We are proposing this AD to detect and correct fatigue cracking around certain fastener locations that could cause multiple window corner skin cracks, which could result in rapid decompression and consequent reduced structural integrity of the airplane.