Data on inspection, diagnosis, repair and operation histories are entered in
a plant-maintenance apparatus for equipment that constitute a plant to be maintained.
Failure-event tree breakdown is performed on failures to be expected for the equipment.
Unreliability is predicted of at least one starting item in the failure-event tree
breakdown. Unreliability of each item in the failure-event tree is calculated based
on a failure unreliability function. Unreliability and a cost of recovery from
each failure event in the failure-event tree are multiplied and results of the
multiplication are accumulated in accordance with the tree breakdown to obtain
a recovery cost. Preventive maintenance expenses are calculated for preventing
failure events. Maintenance timing and technique are decided through comparison
between the recovery cost and the preventive maintenance expenses.
