Airworthiness Directives; Schweizer Aircraft Corporation and Hughes Helicopters, Inc. Model 269A, 269A-1, 269B, 269C, and TH-55A Series Helicopters

Streszczenie

This amendment supersedes an existing airworthiness directive (AD), applicable to Schweizer Aircraft Corporation and Hughes Helicopters, Inc. Model 269A, 269A-1, 269B, 269C, and TH-55A series helicopters, that currently requires repetitive inspections and replacement of certain lower belt drive pulley bearings (pulley bearings). This amendment retains the present AD requirements and adds an alternate pulley bearing to the requirements of the AD. This amendment is prompted by the introduction of an alternate pulley bearing into service by Schweizer Aircraft Corporation. The actions specified by this AD are intended to prevent failure of the pulley bearings, loss of power to the rotor systems, and subsequent loss of control of the helicopter.