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 external visual inspections and internal borescope inspections to detect discrepancies of the elevator assembly; and repair/modification of any discrepancy. This proposal is prompted by a report of fretting at the diagonal truss to web joint of the elevator and cracking in the cap fillet radius adjacent to the joint, apparently due to loose fasteners as a result of local vibration. The actions specified by the proposed AD are intended to detect and correct such fretting and cracking, which could result in reduced structural integrity of the elevator and consequent flutter instability if coupled with other structural failures.