Summary
This action withdraws a notice of proposed rulemaking (NPRM) that proposed a new airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes powered by GE CF6-45/50, P&W JT9D-70, or JT9D-7 series engines. That action would have required repetitive inspections to find cracks and broken fasteners of the inboard and outboard nacelle struts of the rear engine mount bulkhead, and repair, if necessary. For certain airplanes, that action would have provided for an optional terminating modification for the inspections of the outboard nacelle struts. Since the issuance of the NPRM, the Federal Aviation Administration (FAA) has received new data of other issues related to the unsafe condition. The data include many new reports of additional web and frame cracks and sheared attachment fasteners, and reports of cracks on the outboard struts of airplanes not identified in the applicability of the NPRM, in addition to the comments received for the NPRM. We have determined from these data that the corrective actions required by the NPRM are inadequate for ddressing the identified unsafe condition. Accordingly, the proposed rule is withdrawn.