A system for managing replaceable components for equipment having a plurality of components, each with a limited useful life, comprising: a computer with at least one processor; a computer program module for defining a duty profile comprising a plurality of usage cases for the equipment, each usage case involving two or more of the plurality of components and specified operating conditions assumed to be experienced by the involved components during the execution of each of the usage cases; a computer program module for determining a theoretical useful life for each component involved in a duty profile, said theoretical useful life being based on component wear/stress/strain parameters assumed to occur under the specified operating conditions; sensors for determining and monitoring the occurrence of equipment operation corresponding to a usage case and making measurements of actual operating conditions experienced in the operation; a memory for storing the measurements of actual operating conditions for the plurality of components; and a computer program module for computing an adjusted theoretical useful life for a component after it has experienced one or more operations, by: responsive to the measurements of actual operating conditions, calculating one or more calculated wear/stress/strain parameters for each operation and accumulating these calculated parameters for such component; and based on a comparison of the accumulated, calculated wear/stress/strain parameters from actual operating conditions to accumulated wear/stress/strain parameters assumed to occur under the specified operating conditions in the determination of a theoretical useful life, determining the amount of the theoretical useful life consumed in the one or more operations and the resulting adjusted theoretical useful life; wherein the measurements of actual operating conditions comprise measurements of load and the duration of a load; and wherein the duty profile assumes a specified number of operations and the system tracks the number of operations in which a replaceable component is involved. a computer with at least one processor; a computer program module for defining a duty profile comprising a plurality of usage cases for the equipment, each usage case involving two or more of the plurality of components and specified operating conditions assumed to be experienced by the involved components during the execution of each of the usage cases; a computer program module for determining a theoretical useful life for each component involved in a duty profile, said theoretical useful life being based on component wear/stress/strain parameters assumed to occur under the specified operating conditions; sensors for determining and monitoring the occurrence of equipment operation corresponding to a usage case and making measurements of actual operating conditions experienced in the operation; a memory for storing the measurements of actual operating conditions for the plurality of components; and a computer program module for computing an adjusted theoretical useful life for a component after it has experienced one or more operations, by: responsive to the measurements of actual operating conditions, calculating one or more calculated wear/stress/strain parameters for each operation and accumulating these calculated parameters for such component; and based on a comparison of the accumulated, calculated wear/stress/strain parameters from actual operating conditions to accumulated wear/stress/strain parameters assumed to occur under the specified operating conditions in the determination of a theoretical useful life, determining the amount of the theoretical useful life consumed in the one or more operations and the resulting adjusted theoretical useful life; responsive to the measurements of actual operating conditions, calculating one or more calculated wear/stress/strain parameters for each operation and accumulating these calculated parameters for such component; and based on a comparison of the accumulated, calculated wear/stress/strain parameters from actual operating conditions to accumulated wear/stress/strain parameters assumed to occur under the specified operating conditions in the determination of a theoretical useful life, determining the amount of the theoretical useful life consumed in the one or more operations and the resulting adjusted theoretical useful life; wherein the measurements of actual operating conditions comprise measurements of load and the duration of a load; and wherein the duty profile assumes a specified number of operations and the system tracks the number of operations in which a replaceable component is involved.