Action
Final rule.
Summary
We are adopting a new airworthiness directive (AD) for all Turbomeca S.A. ARRIEL 2C, 2C1, 2C2, 2S1, and 2S2 turboshaft engines with modification TU34 or TU34A installed. This AD requires inspecting the torque conformation box (TCB) for correct resistance values and removing TCBs that fail inspection before further flight. This AD was prompted by TCB failures. We are issuing this AD to prevent failure of the TCB, loss of engine thrust control, and damage to the helicopter.