Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Lockheed Model 382, 382B, 382E, 382F, and 382G series airplanes, that currently requires visual inspections to detect loose, missing, or deformed fasteners in the upper truss mounts of certain engines, inspections to detect cracking in the associated tangs, and replacement of damaged parts with new or serviceable parts. This action would require repetitive ultrasonic inspections to detect cracking of the upper tangs and replacement of cracked parts with certain new or serviceable parts. This action would also provide an optional terminating action for the repetitive inspections. Additionally, this action would revise the applicability of the existing rule to specify appropriate groupings of airplanes subject to the rule. This proposal is prompted by reports indicating that fatigue cracking of the tangs of the upper truss mount has been detected. The actions specified by the proposed AD are intended to prevent multiple failures of the upper truss mounts due to problems associated with fatigue cracking, which could adversely affect the integrity of the engine mount structure.