Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes, that currently requires inspections to detect cracking of the front spar web of the wing, and corrective action, if necessary. This action would add one airplane to the applicability, change certain compliance times, add certain new requirements, and provide an optional modification. The actions specified by the proposed AD are intended to detect and correct fatigue cracking of the front spar web, which could result in fuel leaking onto an engine and a consequent fire. This action is intended to address the identified unsafe condition.