Airworthiness Directives; The Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 737-300, -400, and -500 series airplanes. This AD was prompted by a determination that supplemental inspections are required for timely detection of fatigue cracking for certain structural significant items (SSIs). This AD requires revising the maintenance or inspection program, as applicable, to add supplemental inspections. This AD also requires inspections to detect cracks in each SSI, and repair of any cracked structure. We are issuing this AD to address the unsafe condition on these products.