The FAA proposed an Airworthiness Directive for the Eurocopter SA365N, SA365N1, AS365N2, AS365N3, EC155B, EC155B1, SA365C, SA365C1, SA365C2 and SA366G1. It is prompted by reports of corrosion on the main gearbox (MGB) casing lower area between the two servo-control anchor-fitting attachment ribs. The proposed actions are to detect corrosion on the MGB casing, which could lead to a crack, failure of the MGB and subsequent loss of control. The FAA is accepting comments until August 17.