The FAA has issued an airworthiness directive for the Eurocopter EC155B, EC155B1, SA365N1, AS365N2 and AS365N3 requiring visual inspection of the tail-rotor hub for a crack and removal if one is found. The AD is prompted by reports of cracks on two tail-rotor hubs. These actions are intended to prevent the tail rotor from jamming, which could lead to reduced control or loss of control of the helicopter. Eurocopter initially required a visual inspection of the tail-rotor hub every 110 hours but reduced it to 55 flight hours after cracks were found on a second hub.