Airworthiness Directives; Boeing Model 747-100 Series Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 747-100 series airplanes, that currently requires repetitive inspections to detect cracking of the wing front spar web above engine numbers 2 and 3, and repair, if necessary. This amendment requires repetitive inspections to detect cracks in the web and cracked or broken fasteners in an area beyond that specified in the existing AD. This amendment also provides an optional terminating action for the repetitive inspections. This amendment is prompted by reports of broken fasteners and cracking of the web common to the upper and lower chords in an area outside the inspection zone specified in the existing AD. The actions specified by this AD are intended to prevent fuel leakage onto an engine and a resultant fire due to cracking or broken fasteners in the wing front spar.