The FAA is adopting a new airworthiness directive for all Agusta A109S and AW109SP helicopters. A fatigue crack found in the left elevator assembly along the riveting of the upper skin to the fourth rib on an Agusta A109S prompted the AD. The airworthiness directive requirements are designed to detect a crack that could lead to a failure of the elevator, reduced maneuverability of the helicopter, and subsequent loss of control of the helicopter.