Summary
We propose to adopt a new airworthiness directive (AD) for Airbus Helicopters Model AS355E, AS355F, AS355F1, AS355F2, and AS355N helicopters. This proposed AD would require measuring a vibration level in the tail rotor (T/R) drive. This proposed AD is prompted by reports of bearing degradation. The actions of this proposed AD are intended to prevent an unsafe condition on these helicopters.