Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP Series Airplanes

The FAA is revising an existing airworthiness directive (AD) that applies to all Boeing Model 747 series airplanes. That AD currently requires that the FAA-approved maintenance inspection program be revised to include inspections that will give no less than the required damage tolerance rating for each structural significant item, and repair of cracked structure. We issued that AD to ensure the continued structural integrity of the entire fleet of Model 747 series airplanes. This new AD clarifies the applicability of the existing AD by specifying which Boeing Model 747 airplanes are affected by this AD because we have determined that certain new variants that have not yet been certified will not be subject to the requirements of this AD. 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 ensure the continued structural integrity of all Boeing Model 747-100, 747-100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, 747SR, and 747SP series airplanes.