Airworthiness Directives; McDonnell Douglas Model DC-8-11, DC-8-12, DC-8-21, DC-8-31, DC-8-32, DC-8-33, DC-8-41, DC-8-42, and DC-8-43 Airplanes; Model DC-8-51, DC-8-52, DC-8-53, and DC-8-55 Airplanes; Model DC-8F-54 and DC-8F-55 Airplanes; Model DC-8-61, DC-8-62, and DC-8-63 Airplanes; Model DC-8-61F, DC-8-62F, and DC-8-63F Airplanes; Model DC-8-71, DC-8-72, and DC-8-73 Airplanes; and Model DC-8-71F, DC-8-72F, and DC-8-73F Airplanes

The FAA is superseding an existing airworthiness directive (AD), which applies to all McDonnell Douglas Model DC-8 airplanes. That AD currently requires, among other things, revision of an existing program of structural inspections. This new AD requires implementation of a revised program of structural inspections of baseline structure to detect and correct fatigue cracking in order to ensure the continued airworthiness of these airplanes as they approach the manufacturer's original fatigue design life goal. This new AD also reduces the inspection threshold for certain principal structural elements. This AD results from a significant number of these airplanes approaching or exceeding the design service goal on which the initial type certification approval was predicated. We are issuing this AD to detect and correct fatigue cracking that could compromise the structural integrity of these airplanes.