Airworthiness Directives; Boeing Model 747 Series Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that currently requires repetitive inspections to detect fatigue cracking or loose or missing fasteners of the aft torque bulkheads of the outboard nacelle struts; and repair, if necessary. This amendment expands the applicability of the existing AD to include certain additional airplanes, and removes certain other airplanes from the applicability of the existing AD. For all airplanes subject to this AD, this amendment also requires accomplishment of a new terminating action. This action is necessary to prevent fatigue cracking and loose or missing fasteners in the aft torque bulkheads of the outboard nacelle struts, which could result in failure of an outboard nacelle strut diagonal brace load path and possible separation of the nacelle from the wing. This action is intended to address the identified unsafe condition.