to Operate, this cash flow will not create any value. The VDM model can be simplified in certain situations. Assume that we work with Perpetuity. This means there will be indefinitely be a free cash flow that is the same year after year and the SHE factor is constant; the VDM formula thus becomes: PVmaintenance = FSHE,t x (CFAU,t + CFCC,t + CFRA,t + CFSHE,t) / r See also Condition Based Maintenance Corrective maintenance Planned maintenance Reliability Centered Maintenance References External links Article on Value Driven Maintenance Maintenance