Airworthiness Directives; AlliedSignal Inc. (Formerly Textron Lycoming) Model T5313B, T5317A, and T53 (Military) Turboshaft Engines

This amendment revises an existing airworthiness directive (AD), applicable to AlliedSignal Inc. (formerly Textron Lycoming) Model T5313B, T5317A, and T53 series military turboshaft engines approved for installation on aircraft certified in accordance with Section 21.25 of the Federal Aviation Regulations (FAR), that currently requires a one- time visual inspection of accessory drive carrier assemblies for affected serial numbers (S/Ns) designating a defective assembly, and if the S/N is applicable, replacement with a serviceable assembly. This amendment adds military helicopter models and removes one civilian helicopter model to the sentence in the Applicability paragraph of the AD that provides guidance as to the helicopter models with the affected engines. This amendment is prompted by the need to revise the Applicability paragraph. The actions specified by this AD are intended to prevent accessory drive carrier assembly failure, which could result in an N2 overspeed and an uncontained engine failure.