Image of the fracture surface of the fulcrum ring.  The failure was due to bending fatigue, with multiple initiation sites located at the extrados, or 8:00-10:00 positions.  Crack propagation was a progressive event from left to right.  The crack grew by progressive advancement of the crack front with each actuation of the clutch.  Final failure was at the intrados, at the 2:00-4:00 positions.  Failure of the clutch occurred shortly thereafter when the ring shifted location.