Airworthiness Directives; General Electric Company (GE) CT7-8A Turboshaft Engines

The FAA is superseding an existing airworthiness directive (AD) for certain GE CT7-8A turboshaft engines. That AD currently requires initial and repetitive inspections of the electrical chip detectors for the No. 3 bearing. This AD requires removing from service certain GE CT7-8A turboshaft engines within 6,200 cycles-since-new. This AD results from investigation for the root causes of two failures of the No. 3 bearing. We are issuing this AD to prevent failure of the No. 3 bearing due to contamination by aluminum oxide, which could result in a possible in-flight shutdown of the engines and loss of control or forced landing of the aircraft.