Igor was a clever chap and the Bifilars are a cool way of correcting for the change of disk c of g with cyclic changes to disc path plane on the S61 and S76. Bell has used a similar method with the pendulum dampers on the 412. All works well as long as the lateral movement on the bearings is kept to a minimum. Hint to 412 drivers look out for brunelling(?) on the needle bearings during preflight inspections.
Outhouse