Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Airbus Model A300, A300-600, and A310 series airplanes, that currently requires inspections to detect cracks in the lower spar axis of the nacelle pylon between ribs 9 and 10, and repair, if necessary. The existing AD also provides for optional modification of the pylon, which terminates the inspections for Model A300 and A310 series airplanes and increases the threshold and repetitive interval of the inspections for Model A300-600 series airplanes. This action would reduce the inspection threshold and require repetitive inspections following accomplishment of the optional modification for Model A310 series airplanes. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed AD are intended to prevent fatigue cracking, which could result in reduced structural integrity of the lower spar of the pylon.