Airworthiness Directives; Boeing Model 747-100, -100B, -100B SUD, -200B, -200C, -200F, and -300 Series Airplanes; and Model 747SP and 747SR Series Airplanes; Equipped With Pratt & Whitney JT9D-3 and -7 (Except -70) Series Engines or General Electric CF6-50 Series Engines With Modified JT9D-7 Inboard Struts

The FAA is adopting a new airworthiness directive (AD) for certain Boeing airplanes listed above. This AD requires repetitive detailed inspections of the midspar web of the inboard and/or outboard struts for cracking, disbonding, or buckling; repetitive detailed inspections of the midspar stiffeners for any crack or fracture; related investigative actions; and corrective actions, if necessary. This AD is prompted by reports of cracking in the midspar web. We are issuing this AD to detect and correct cracking in the midspar assembly, which could result in the loss of the midspar assembly load path, and could, combined with the loss of the nacelle station 180 bulkhead load path, lead to the separation of the engine from the airplane.