Airworthiness Directives; Boeing Model 747-200B and -200F Series Airplanes Powered by Pratt & Whitney JT9D-70 Series Engines

This amendment adopts a new airworthiness directive (AD), applicable to certain Boeing Model 747-200B and -200F series airplanes powered by Pratt & Whitney JT9D-70 series engines, that requires repetitive detailed inspections of the pylon skin and internal structure of the nacelle struts adjacent to and aft of the precooler exhaust vent for heat damage (discoloration), wrinkling, and cracking; and corrective action, if necessary. The actions specified by this AD are intended to find and fix such damage, which could result in cracking or fracture of the nacelle struts, and consequent reduced structural integrity and possible separation of the strut and engine from the airplane. This action is intended to address the identified unsafe condition.