Airworthiness Directives; Hélicoptères Guimbal Helicopters

The FAA is adopting a new airworthiness directive (AD) for all H[eacute]licopt[egrave]res Guimbal (HG) Model Cabri G2 helicopters. The FAA previously sent this AD as an emergency AD to all known U.S. owners and operators of these helicopters. This AD was prompted by a report that was received of a crack on the main rotor (MR) mast after the crew reported an abnormal increase of vibration. This AD requires inspecting the MR mast for cracks and corrosion pitting, and depending on the results of the inspection, accomplishing corrective actions. This AD also requires modifying the MR mast, which includes applying corrosion protection to the MR mast, reporting the inspection results and prohibiting the installation of a certain main gear box (MGB), unless certain requirements are met. The FAA is issuing this AD to address the unsafe condition on these products.