The problem was resolved by increasing the tightening torque
applied to the bolt so that a higher proportion of its yield
strength was used.
The strength of the fastener was not being utilised, reducing
the preload that the fastener was capable of providing. A tightening
torque of 300 Nm was subsequently specified that resulted in
a preload of 119000 N that was sufficient to sustain the forces
applied to the joint.
another example of a bolt failure