Airworthiness Directives; Boeing Model 747 Airplanes

The FAA is superseding an existing airworthiness directive (AD), which applies to all Boeing Model 747 series airplanes. That AD currently requires repetitive inspections for cracking of the top and side panel webs and panel stiffeners of the nose wheel well (NWW), and corrective actions if necessary. This new AD reduces the interval for certain repetitive inspections and removes a certain optional inspection. This new AD also requires replacing the NWW side and top panels with new panels, which terminates the repetitive inspections. This AD results from the development of a new modification. We are issuing this AD to prevent fatigue cracks in the top and side panel webs and stiffeners of the NWW, which could compromise the structural integrity of the NWW and could lead to the rapid decompression of the airplane.