Airworthiness Directives; The Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 737-400 series airplanes. This AD was prompted by reports of cracks in the upper chord of the overwing stub beams at body station (STA) 578 emanating from the rivet location common to the crease beam inner chord and the overwing stub beam upper chord. This AD requires repetitive inspections for cracking, and related investigative and corrective actions if necessary. We are issuing this AD to prevent the unsafe condition on these products.