Airworthiness Directives; Agusta S.p.A. Helicopters
We are adopting a new airworthiness directive (AD) for Agusta S.p.A. (Agusta) Model AB139 and AW139 helicopters. This AD requires inspecting each full ice protection system tail rotor slip ring (slip ring) for chatter marks, witness marks, or scoring, and determining the depth of each mounting hole. Based on the findings from the inspection, this AD requires either re-identifying the slip ring or replacing the slip ring. This AD is prompted by two incidents of the slip ring body separating from the supporting flange due to improper torque. These actions are intended to prevent separation of the mounting flange from the slip ring body and subsequent loss of control of the helicopter.