Airworthiness Directives; Boeing Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, -300, 747SP, and 747SR Series Airplanes Powered by General Electric (GE) CF6-45/50 and Pratt & Whitney (P&W) JT9D-70, JT9D-3 or JT9D-7 Series Engines

We are adopting a new airworthiness directive (AD) for certain Boeing Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, -300, 747SP, and 747SR series airplanes powered by General Electric (GE) CF6- 45/50 and Pratt & Whitney (P&W) JT9D-70, JT9D-3, or JT9D-7 series engines. This AD requires repetitive inspections to find cracks and broken fasteners of the rear engine mount bulkhead of the inboard and outboard nacelle struts, and repair if necessary. For certain airplanes, this AD mandates a terminating modification for certain inspections of the inboard and outboard nacelle struts. This AD results from reports of web and frame cracks and sheared attachment fasteners on the inboard and outboard nacelle struts. We are issuing this AD to detect and correct cracks and broken fasteners of the inboard and outboard nacelle struts, which could result in possible loss of the rear engine mount bulkhead load path and consequent separation of the engine from the airplane.