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 detailed visual inspections to find discrepancies of the installation of the midspar fuse pins of the inboard and outboard struts, and follow-on actions, if necessary. That AD also provides for an optional terminating modification for the repetitive inspections. This amendment continues to require repetitive detailed visual inspections to find discrepancies of the installation of the midspar fuse pins of the inboard and outboard struts, and follow-on actions, if necessary. This amendment mandates accomplishment of the previously optional terminating modification. The actions specified by this AD are intended to find and fix discrepancies of the installation of the midspar fuse pins, which could result in loss of the secondary retention capability of the fuse pins, migration of the fuse pins, and consequent loss of the strut and engine from the airplane. This action is intended to address the identified unsafe condition.