Baranfin,
Without wishing to get too technical, the tie bar is a flexible "Joint" which connects the rotor blade to the head or head extension arms. Used on both the Lynx and Gazelle, amongst others. Obviously it has to be very strong in order to deal with the considerable centrifugal loads placed upon it. It also has to be flexible enough to allow for the flapping and twisting motion of the blades as they fly through the air. Originally there were thought to be so "over engineered" that they would never fail under normal use. Sadly, in September 1994, this proved not to be the case and two AAC crew died when a Lynx main rotor blade departed the aircraft in flight. Wastelands then went to great lengths to assure all of us flying the Lynx at the time that it was a one off failure and reduced inspection times, combined with better quality control, would ensure that it would not happen again. Then.
