Airworthiness Directives; Boeing Model 737-300, -400, and -500 Series Airplanes

We are adopting a new airworthiness directive (AD) for all Boeing Model 737-300, -400, and -500 series airplanes. This AD requires revising the FAA-approved maintenance inspection program to include inspections that will give no less than the required damage tolerance rating for each structural significant item (SSI), doing repetitive inspections to detect cracks of all SSIs, and repairing cracked structure. This AD results from a report of incidents involving fatigue cracking in transport category airplanes that are approaching or have exceeded their design service objective. We are issuing this AD to maintain the continued structural integrity of the entire fleet of Model 737-300, -400, and -500 series airplanes.