Summary
This document revises an earlier proposed airworthiness directive (AD), applicable to all Lockheed Model L-1011-385 series airplanes, that would have required repetitive inspections to detect corrosion or fatigue cracking of certain structural elements of the airplane; corrective actions if necessary; and incorporation of certain structural modifications. This new action revises the proposed rule by referencing a new service bulletin that, among other changes, corrects the effectivity and revises the modification threshold of various secondary service bulletins. The actions specified by this new proposed AD are intended to prevent corrosion or fatigue cracking of certain structural elements, which could result in reduced structural integrity of the airplane. This action is intended to address the identified unsafe condition.