AD FAA-2008-0669

We are adopting a new airworthiness directive (AD) for certain Model 737-600, -700, and -800 series airplanes. This AD requires an inspection of the free flange, vertical web, and radius between the free flange and vertical web of the lower stringers of the wing center section for drill starts, and applicable related investigative and corrective actions. This AD results from drill starts being found on the free flange of the lower stringers of the wing center section during a quality assurance inspection at the final assembly plant. We are issuing this AD to prevent cracks from propagating from drill starts in the free flange, vertical web, and radius between the free flange and vertical web of the lower stringers of the wing center section lower stringers, which could cause a loss of structural integrity of the wing center section and may result in a fuel leak.