Airworthiness Directives; Turbomeca S.A. Turboshaft Engines

We are adopting a new airworthiness directive (AD) for certain Turbomeca S.A. Arriel 1A1, 1A2, 1B, 1C, 1C1, 1C2, 1D, 1D1, 1E2, 1K1, 1S, and 1S1 turboshaft engines. This AD requires daily post-flight checks of the engine tachometer's unit cycle-counting feature. This AD also requires ground-run functional checks within every 1,000 operating hours. This AD was prompted by detailed analysis and review of the accuracy of the engine's tachometer cycle-counting feature. We are issuing this AD to prevent uncontained engine failure and damage to the helicopter.