Airworthiness Directives; Turbomeca Arriel 1B, 1D, 1D1, and 1S1 Turboshaft Engines

The FAA is adopting a new airworthiness directive (AD) for certain Turbomeca Arriel 1B, 1D, 1D1, and 1S1 turboshaft engines. This AD requires initial and repetitive position checks of the gas generator 2nd stage turbine blades on all Turbomeca Arriel 1B, 1D, 1D1, and 1S1 turboshaft engines, and initial and repetitive replacements of 2nd stage turbines on 1B, 1D, and 1D1 engines only. This AD results from reports of the release of gas generator 2nd stage turbine blades while in service, with full containment of debris. We are issuing this AD to prevent inflight engine shutdown and subsequent forced autorotation landing or accident.