AD FAA-2017-1077

The FAA is adopting a new airworthiness directive (AD) for certain Leonardo S.p.a. Model AB412 helicopters. This AD was prompted by a cracked spiral bevel gear. This AD requires a one-time visual inspection and a recurring fluorescent magnetic particle inspection (FMPI) of affected spiral bevel gears for a crack, and depending on the inspection results, removing the spiral bevel gear from service. This AD also prohibits installing an affected spiral bevel gear unless it has recently passed an FMPI. The FAA is issuing this AD to address the unsafe condition on these products.