Incident + Flaws = Chain Reaction

Permanent Failures wait to be triggered

Faulty Management decisions cause human or technical errors;

Add missing or ineffective defense systems: Here is  the failure

Chain Reaction triggering a Quality Defect

This model describes, how a Loss Events develops through a sequence of factors:

  • Failure: e.g. the driving shaft breaks and the machine cannot function any more
  • Fault in the System Defense: e.g. the friction clutch, that is supposed to protect the main drive against excessive torque, doesn’t (it sticks due to poor Maintenance)
  • Active Fault: e.g. the operator doesn’t stop the feed in time, when the slide approaches the machine bed; the slid moves against the bed. The drive is blocked
  • Failure Precondition: e.g. the operator is being stressed and doesn’t see that he is damaging the main drive
  • Basic Risk Factor: Management had decided to employ cheaper personnel lacking training and experience

Chain Reaction triggering a Quality Defect: Machine tool shaft breaking, when operator moves slide against bed):