AD FAA-2013-0340

We are adopting a new airworthiness directive (AD) for Eurocopter Deutschland GmbH (Eurocopter) Model EC135 P1, EC135 P2, EC135 P2+, EC135 T1, EC135 T2, EC135 T2+, and MBB-BK 117 C-2 helicopters with a certain external mounted hoist system (hoist) with boom support assembly (boom) installed. This AD requires inspecting the boom for a crack and, if a crack exists, replacing the boom with an airworthy boom. Until the boom is inspected, this AD requires, before further flight, and thereafter before the first flight of each day, checking the hoist for a crack. This AD was prompted by cracks found on the boom during a pre-flight check of a hoist on an MBB-BK 117 C-2 helicopter. The actions of this AD are intended to detect a crack and prevent failure of the boom, loss of the boom and attached loads, and subsequent loss of helicopter control.