Airworthiness Directives; Airbus Model A300-600 Series Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Airbus Model A300-600 series airplanes, that currently requires repetitive ultrasonic inspections to detect cracks in the bolt holes inboard and outboard of rib 9 on the bottom booms of the front and rear wing spars, and repair, if necessary. This amendment requires revising the compliance thresholds for the inspection and requires that the inspections be repeated at reduced intervals. This amendment is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent fatigue cracks in the bolt holes of the wing spars, which could result in reduced structural integrity of a wing spar.