Airworthiness Directives; General Electric Company CF34-8E Series Turbofan Engines

The FAA is superseding an existing airworthiness directive (AD) for General Electric Company (GE) CF34-8E series turbofan engines with certain serial number (SN) master variable geometry (VG) actuators installed. That AD currently requires initial and repetitive reviews of the airplane computer systems for master VG actuator fault messages. That AD also requires replacement of actuators reported faulty by the Full Authority Digital Engine Control (FADEC). This AD requires the same reviews. This AD also prohibits installation of affected master VG actuators onto any CF34-8E series turbofan engine after the effective date of the AD. This AD results from the need to add to the list of affected parts, master VG actuators made by a parts manufacturing approval (PMA) holder. We are issuing this AD to prevent dual-channel electrical signal faults in the master VG actuator which will cause an uncommanded reduction of thrust to idle with a subsequent loss of the ability to advance thrust above idle, and will result in a multiengine loss of thrust if dual-channel faults occur on more than one engine simultaneously.