AD FAA-2012-0501

We are adopting a new airworthiness directive (AD) for Agusta S.p.A. (Agusta) Model A109E and Model A109S helicopters with certain lower semichannel assemblies installed. This AD requires a one-time inspection of the lower semichannel assemblies to determine if metallic spacers are installed. If the metallic spacers are installed, this AD requires an inspection for the correct installation of the metallic spacers on the semichannels and for the correct seating of the gaskets. If the metallic spacers are not installed with rivets, the lower semichannel assemblies must be modified, and the main drive shaft must be inspected for damage. This AD was prompted by reports of damage to the main drive shaft caused by improperly secured metallic spacers on some A109 model helicopters. The actions of this AD are intended to detect missing spacer rivets, which could allow the metallic spacers to rotate and lead to damage and failure of the main drive shaft, and subsequent loss of helicopter control.