Airworthiness Directives; Turbomeca Arriel 1A1, 1A2, 1B, 1C, 1C1, 1C2, 1D, 1D1, 1E2, 1K1, 1S, and 1S1 Turboshaft Engines

The FAA is superseding an existing airworthiness directive (AD) for Turbomeca Arriel 1A1, 1A2, 1B, 1C, 1C1, 1C2, 1D, 1D1, 1E2, 1K1, 1S, and 1S1 turboshaft engines. That AD currently requires initial and repetitive visual inspections of certain reduction gearboxes (module M05) for oil leakage, repair if leaking, and repair of all affected modules as optional terminating action to the repetitive inspections. This AD requires the same actions, but adds five more serial numbers of the reduction gearboxes (module M05) that are affected, and adds an alternative optional terminating action to the repetitive visual inspections. This AD results from Turbomeca identifying five additional reduction gearboxes (module M05) affected, and adding an alternative optional terminating action to the repetitive visual inspections. We are issuing this AD to prevent uncommanded in- flight engine shutdown, possible engine fire, and an emergency autorotation landing.