Summary
This document proposes the supersedure of an existing airworthiness directive (AD) for 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. That AD currently requires creating a component log card or equivalent record and determining the calendar age and number of flights on each tension-torsion (TT) strap. That AD also requires inspecting and removing, as necessary, certain unairworthy TT straps. This action would establish a life limit for certain main rotor TT straps. This proposal is prompted by a need to establish a life limit for certain TT straps because of an accident in which a main rotor blade (blade) separated from an ECD Model MBB-BK 117 helicopter due to fatigue failure of a TT strap. The same part-numbered TT strap is used on the ECD Model BO-105 helicopters. The actions specified by this AD are intended to prevent fatigue failure of the TT strap, loss of a blade, and subsequent loss of control of the helicopter.