Airworthiness Directives; Eurocopter Deutschland GmbH (ECD) Model BO-105A, BO-105C, BO-105 C-2, BO-105 CB-2, BO-105 CB-4, BO-105S, BO-105 CS-2, BO-105 CBS-2, BO-105 CBS-4, and BO-105LS A-1 Helicopters

This amendment adopts a new airworthiness directive (AD) for Eurocopter Deutschland GmbH (ECD) (Eurocopter) Model BO-105A, BO-105C, BO-105 C-2, BO-105 CB-2, BO-105 CB-4, BO-105S, BO-105 CS-2, BO-105 CBS- 2, BO-105 CBS-4, and BO-105LS A-1 helicopters. This action requires creating a component log card or equivalent record and determining the calendar age, number of flights, and flight hours time-in-service (TIS) on two part-numbered tension-torsion (T-T) straps; inspecting and replacing certain T-T straps, as necessary; and modifying certain main rotor heads if alternate T-T straps are installed. This action also establishes an additional life limit for these two part-numbered T-T straps. This amendment is prompted by an accident in which a main rotor blade separated from a Eurocopter Model MBB-BK 117 helicopter due to fatigue failure of a T-T strap. The same part-numbered T-T strap is used on Eurocopter Model BO-105 helicopters. That accident indicated a need to establish an additional life limit for certain part-numbered T- T straps. The actions specified in this AD are intended to prevent fatigue failure of a T-T strap, loss of a main rotor blade, and subsequent loss of control of the helicopter.