A computer-implemented method for processing spare parts purchase orders includes receiving, during a manufacturing planning phase, an estimate of the number of the spare parts that will be needed to be produced during a given period to satisfy expected purchase orders for the spare part. The method also includes receiving a user-defined configurable reasonable quantity rule to be used during processing of electronic purchase order information. The method further includes, upon receipt of an electronic purchase order, determining whether a quantity value included in the electronic purchase order is reasonable using the defined reasonable quantity check rule, and if determined unreasonable, generating an indication that the quantity value was determined to be unreasonable.