Summary
This document proposes the supersedure of an existing priority letter airworthiness directive (AD), applicable to certain Bell Helicopter Textron, Inc. Model 412 helicopters, that currently requires a daily inspection of certain swashplate support assemblies. It also requires a reduction in V<INF>NE, and installation of appropriate airspeed indicator markings and a placard. This action would require the same actions required by the existing Priority Letter AD, but would restrict the applicability to the Model 412 helicopters with a certain steel main rotor control swashplate support assembly (steel swashplate support assembly) installed. This AD also proposes to allow the installation of an improved main rotor control swashplate assembly that terminates the requirements of this AD. This proposal is prompted by reported cracks and in-service failures of certain steel swashplate support assemblies. The actions specified by the proposed AD are intended to prevent failure of the steel swashplate support assembly that could result in loss of main rotor control and subsequent loss of control of the helicopter.