Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Lockheed Model L-1011-385 series airplanes. This proposal would require repetitive inspections to detect cracking of the fuselage skin in the areas of the left- and right-hand stringerless sidewall window belts, and repair, if necessary. This proposal is prompted by reports of fatigue cracks found in the fuselage skin where the skin thickness steps from 0.40 to 0.23 inch. The actions specified by the proposed AD are intended to detect and correct cracking of the fuselage skin, which could result in reduced structural integrity of the airplane.