DRS MSS Chesapeake provides spares modeling for developing spares lists, including Installation and Checkout/On-board Repair Parts (INCO/OBRP) documents, as well as sparing lists for proposals.
Spares requirements are developed following MIL-HDBK-217F and the requirements of the contract or RFP.
We use Windchill software for spares forecasting, which is also used for our Reliability analysis. This tool enables us to maintain a database of parts and metrics that can be updated as design changes are proposed. Using the same equipment data, we efficiently update several analyses (Reliability, Level of Repair Analysis (LORA), Spares, Reliability Block Diagrams) for various engineering studies.
These models use a Poisson algorithm to determine the sparing distribution. The Poisson probability function is applicable for sparing analysis when the opportunity for failure occurrence is large, but actual occurrence is unlikely. This formula is a standard commercial industry methodology for spare part quantity determination